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KASAN: slab-use-after-free Read in disk_add_events

syzbot syzbot 3 participants 7 messages Jul 29, 2025 – Jul 30, 2025

Subsystems (3)
VFS Block layer MD RAID
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syzbot

author syzbot
#0 lore raw

Hello,

syzbot found the following issue on:

HEAD commit:    ced1b9e0392d Merge tag 'ata-6.17-rc1' of git://git.kernel...
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=133b8cf0580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=52c12ce9080f644c
dashboard link: https://syzkaller.appspot.com/bug?extid=fa3a12519f0d3fd4ec16
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=154b31bc580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=171a9782580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-ced1b9e0.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/c709b0d9538c/vmlinux-ced1b9e0.xz
kernel image: https://storage.googleapis.com/syzbot-assets/129af0799fa3/bzImage-ced1b9e0.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:

Reported-by [email protected]

==================================================================

BUG: KASAN: slab-use-after-free in __list_add_valid_or_report+0x151/0x190 lib/list_debug.c:32
Read of size 8 at addr ffff888036fa1400 by task syz.2.1231/9834

CPU: 3 UID: 0 PID: 9834 Comm: syz.2.1231 Not tainted 6.16.0-syzkaller-00857-gced1b9e0392d #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xcd/0x630 mm/kasan/report.c:482
 kasan_report+0xe0/0x110 mm/kasan/report.c:595
 __list_add_valid_or_report+0x151/0x190 lib/list_debug.c:32
 __list_add_valid include/linux/list.h:88 [inline]
 __list_add include/linux/list.h:150 [inline]
 list_add_tail include/linux/list.h:183 [inline]
 disk_add_events+0x90/0x170 block/disk-events.c:463
 add_disk_final block/genhd.c:427 [inline]
 add_disk_fwnode+0x3c8/0x5d0 block/genhd.c:610
 add_disk include/linux/blkdev.h:773 [inline]
 md_alloc+0x3c2/0x1080 drivers/md/md.c:5981
 md_alloc_and_put drivers/md/md.c:6016 [inline]
 md_probe drivers/md/md.c:6029 [inline]
 md_probe+0x6e/0xd0 drivers/md/md.c:6024
 blk_probe_dev+0x116/0x1a0 block/genhd.c:884
 blk_request_module+0x16/0xb0 block/genhd.c:897
 blkdev_get_no_open+0x9b/0x100 block/bdev.c:825
 blkdev_open+0x141/0x3f0 block/fops.c:684
 do_dentry_open+0x744/0x1c10 fs/open.c:965
 vfs_open+0x82/0x3f0 fs/open.c:1095
 do_open fs/namei.c:3887 [inline]
 path_openat+0x1de4/0x2cb0 fs/namei.c:4046
 do_filp_open+0x20b/0x470 fs/namei.c:4073
 do_sys_openat2+0x11b/0x1d0 fs/open.c:1435
 do_sys_open fs/open.c:1450 [inline]
 __do_sys_openat fs/open.c:1466 [inline]
 __se_sys_openat fs/open.c:1461 [inline]
 __x64_sys_openat+0x174/0x210 fs/open.c:1461
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f4ea558e9a9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f4ea645e038 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f4ea57b6080 RCX: 00007f4ea558e9a9
RDX: 0000000000000000 RSI: 0000200000000a80 RDI: ffffffffffffff9c
RBP: 00007f4ea5610d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f4ea57b6080 R15: 00007fff25d53038
 </TASK>

Allocated by task 9822:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
 kasan_save_track+0x14/0x30 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
 __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:394
 kmalloc_noprof include/linux/slab.h:905 [inline]
 kzalloc_noprof include/linux/slab.h:1039 [inline]
 disk_alloc_events+0xf0/0x3f0 block/disk-events.c:439
 __add_disk+0x475/0xf00 block/genhd.c:500
 add_disk_fwnode+0x3f8/0x5d0 block/genhd.c:601
 add_disk include/linux/blkdev.h:773 [inline]
 md_alloc+0x3c2/0x1080 drivers/md/md.c:5981
 md_alloc_and_put drivers/md/md.c:6016 [inline]
 md_probe drivers/md/md.c:6029 [inline]
 md_probe+0x6e/0xd0 drivers/md/md.c:6024
 blk_probe_dev+0x116/0x1a0 block/genhd.c:884
 blk_request_module+0x16/0xb0 block/genhd.c:897
 blkdev_get_no_open+0x9b/0x100 block/bdev.c:825
 blkdev_open+0x141/0x3f0 block/fops.c:684
 do_dentry_open+0x744/0x1c10 fs/open.c:965
 vfs_open+0x82/0x3f0 fs/open.c:1095
 do_open fs/namei.c:3887 [inline]
 path_openat+0x1de4/0x2cb0 fs/namei.c:4046
 do_filp_open+0x20b/0x470 fs/namei.c:4073
 do_sys_openat2+0x11b/0x1d0 fs/open.c:1435
 do_sys_open fs/open.c:1450 [inline]
 __do_sys_openat fs/open.c:1466 [inline]
 __se_sys_openat fs/open.c:1461 [inline]
 __x64_sys_openat+0x174/0x210 fs/open.c:1461
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 9817:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
 kasan_save_track+0x14/0x30 mm/kasan/common.c:68
 kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:576
 poison_slab_object mm/kasan/common.c:247 [inline]
 __kasan_slab_free+0x51/0x70 mm/kasan/common.c:264
 kasan_slab_free include/linux/kasan.h:233 [inline]
 slab_free_hook mm/slub.c:2381 [inline]
 slab_free mm/slub.c:4643 [inline]
 kfree+0x2b4/0x4d0 mm/slub.c:4842
 disk_release+0x161/0x410 block/genhd.c:1301
 device_release+0xa1/0x240 drivers/base/core.c:2568
 kobject_cleanup lib/kobject.c:689 [inline]
 kobject_release lib/kobject.c:720 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x1e7/0x5a0 lib/kobject.c:737
 put_device+0x1f/0x30 drivers/base/core.c:3800
 blkdev_release+0x15/0x20 block/fops.c:699
 __fput+0x402/0xb70 fs/file_table.c:468
 task_work_run+0x14d/0x240 kernel/task_work.c:227
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop+0xeb/0x110 kernel/entry/common.c:114
 exit_to_user_mode_prepare include/linux/entry-common.h:330 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:414 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:449 [inline]
 do_syscall_64+0x3f6/0x4c0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff888036fa1400
 which belongs to the cache kmalloc-512 of size 512

The buggy address is located 0 bytes inside of
freed 512-byte region [ffff888036fa1400, ffff888036fa1600)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x36fa0
head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88801b842c80 dead000000000100 dead000000000122
raw: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000

head: 00fff00000000040 ffff88801b842c80 dead000000000100 dead000000000122
head: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
head: 00fff00000000002 ffffea0000dbe801 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000004

page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 2, tgid 2 (kthreadd), ts 71482349709, free_ts 68765218476
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1c0/0x230 mm/page_alloc.c:1704
 prep_new_page mm/page_alloc.c:1712 [inline]
 get_page_from_freelist+0x1321/0x3890 mm/page_alloc.c:3669
 __alloc_frozen_pages_noprof+0x261/0x23f0 mm/page_alloc.c:4959
 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2419
 alloc_slab_page mm/slub.c:2451 [inline]
 allocate_slab mm/slub.c:2619 [inline]
 new_slab+0x23b/0x330 mm/slub.c:2673
 ___slab_alloc+0xd9c/0x1940 mm/slub.c:3859
 __slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3949
 __slab_alloc_node mm/slub.c:4024 [inline]
 slab_alloc_node mm/slub.c:4185 [inline]
 __kmalloc_cache_noprof+0xfb/0x3e0 mm/slub.c:4354
 kmalloc_noprof include/linux/slab.h:905 [inline]
 kzalloc_noprof include/linux/slab.h:1039 [inline]
 set_kthread_struct+0xcb/0x380 kernel/kthread.c:126
 copy_process+0x3107/0x7650 kernel/fork.c:2097
 kernel_clone+0xfc/0x960 kernel/fork.c:2599
 kernel_thread+0xd4/0x120 kernel/fork.c:2661
 create_kthread kernel/kthread.c:487 [inline]
 kthreadd+0x503/0x800 kernel/kthread.c:847
 ret_from_fork+0x5d4/0x6f0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
page last free pid 6016 tgid 6016 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1248 [inline]
 __free_frozen_pages+0x7fe/0x1180 mm/page_alloc.c:2706
 vfree+0x1fd/0xb50 mm/vmalloc.c:3434
 kcov_put kernel/kcov.c:439 [inline]
 kcov_put kernel/kcov.c:435 [inline]
 kcov_close+0x34/0x60 kernel/kcov.c:535
 __fput+0x402/0xb70 fs/file_table.c:468
 task_work_run+0x14d/0x240 kernel/task_work.c:227
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x86c/0x2bd0 kernel/exit.c:964
 do_group_exit+0xd3/0x2a0 kernel/exit.c:1105
 get_signal+0x2673/0x26d0 kernel/signal.c:3034
 arch_do_signal_or_restart+0x8f/0x7d0 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop+0x84/0x110 kernel/entry/common.c:111
 exit_to_user_mode_prepare include/linux/entry-common.h:330 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:414 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:449 [inline]
 do_syscall_64+0x3f6/0x4c0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff888036fa1300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888036fa1380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888036fa1400: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff888036fa1480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888036fa1500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

---
This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at [email protected].

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

#1 lore raw

syztest

#syz test

drivers/md/md.c +3 -4
@@ -5978,10 +5978,6 @@ struct mddev *md_alloc(dev_t dev, char *name)
 
 	disk->events |= DISK_EVENT_MEDIA_CHANGE;
 	mddev->gendisk = disk;
-	error = add_disk(disk);
-	if (error)
-		goto out_put_disk;
-
 	kobject_init(&mddev->kobj, &md_ktype);
 	error = kobject_add(&mddev->kobj, &disk_to_dev(disk)->kobj, "%s", "md");
 	if (error) {

@@ -5999,6 +5995,9 @@ struct mddev *md_alloc(dev_t dev, char *name)
 	kobject_uevent(&mddev->kobj, KOBJ_ADD);
 	mddev->sysfs_state = sysfs_get_dirent_safe(mddev->kobj.sd, "array_state");
 	mddev->sysfs_level = sysfs_get_dirent_safe(mddev->kobj.sd, "level");
+	error = add_disk(disk);
+	if (error)
+		goto out_put_disk;
 	mutex_unlock(&disks_mutex);
 	return mddev;
Signature · 1 line
2.43.0
#2 lore raw

Re: syztest

Hi,

Quoted 5 lines · Arnaud Lecomte

#syz test

drivers/md/md.c struct mddev *md_alloc(dev_t dev, char *name) · line 5982

Quoted 9 lines
drivers/md/md.c +0 -4
@@ -5978,10 +5978,6 @@ struct mddev *md_alloc(dev_t dev, char *name)
 
  	disk->events |= DISK_EVENT_MEDIA_CHANGE;
  	mddev->gendisk = disk;
-	error = add_disk(disk);
-	if (error)
-		goto out_put_disk;
-
  	kobject_init(&mddev->kobj, &md_ktype);
  	error = kobject_add(&mddev->kobj, &disk_to_dev(disk)->kobj, "%s", "md");

This is wrong, you can't add mddev >kobj under the disk without kobject_add for the disk kobj.

Thanks,
Kuai

Quoted 12 lines
drivers/md/md.c +3 -0
  	if (error) {

@@ -5999,6 +5995,9 @@ struct mddev *md_alloc(dev_t dev, char *name)
  	kobject_uevent(&mddev->kobj, KOBJ_ADD);
  	mddev->sysfs_state = sysfs_get_dirent_safe(mddev->kobj.sd, "array_state");
  	mddev->sysfs_level = sysfs_get_dirent_safe(mddev->kobj.sd, "level");
+	error = add_disk(disk);
+	if (error)
+		goto out_put_disk;
  	mutex_unlock(&disks_mutex);
  	return mddev;
#3 lore raw

Re: syztest

Quoted 5 lines · Yu Kuai

Hi,

Quoted 2 lines · Arnaud Lecomte

#syz test

Quoted 15 lines

drivers/md/md.c struct mddev *md_alloc(dev_t dev, char *name) · line 5981

Quoted 11 lines
drivers/md/md.c +0 -4
@@ -5978,10 +5978,6 @@ struct mddev *md_alloc(dev_t dev, char *name)
         disk->events |= DISK_EVENT_MEDIA_CHANGE;
       mddev->gendisk = disk;
-    error = add_disk(disk);
-    if (error)
-        goto out_put_disk;
-
       kobject_init(&mddev->kobj, &md_ktype);
       error = kobject_add(&mddev->kobj, &disk_to_dev(disk)->kobj, "%s", "md");

This is wrong, you can't add mddev >kobj under the disk without kobject_add for the disk kobj.

Will dive a bit more into that after work,
Thanks

Quoted 15 lines

Thanks,
Kuai

Quoted 11 lines
drivers/md/md.c +3 -0
       if (error) {

@@ -5999,6 +5995,9 @@ struct mddev *md_alloc(dev_t dev, char *name)
       kobject_uevent(&mddev->kobj, KOBJ_ADD);
       mddev->sysfs_state = sysfs_get_dirent_safe(mddev->kobj.sd, "array_state");
       mddev->sysfs_level = sysfs_get_dirent_safe(mddev->kobj.sd, "level");
+    error = add_disk(disk);
+    if (error)
+        goto out_put_disk;
       mutex_unlock(&disks_mutex);
       return mddev;
author syzbot Tested-by
#4 lore raw
In reply to Arnaud Lecomte
syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by [email protected]
Tested-by [email protected]

Tested on:

commit:         4b290aae Merge tag 'sysctl-6.17-rc1' of git://git.kern..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10908834580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=295b41325f4e1bab
dashboard link: https://syzkaller.appspot.com/bug?extid=fa3a12519f0d3fd4ec16
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=15ac34a2580000

Note: testing is done by a robot and is best-effort only.

#5 lore raw
In reply to syzbot

+CC Xiao

Quoted 4 lines · syzbot

Hello,

syzbot found the following issue on:

Quoted 9 lines
HEAD commit:    ced1b9e0392d Merge tag 'ata-6.17-rc1' of git://git.kernel...
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=133b8cf0580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=52c12ce9080f644c
dashboard link: https://syzkaller.appspot.com/bug?extid=fa3a12519f0d3fd4ec16
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=154b31bc580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=171a9782580000

This looks like the same cause with another report:

https://lore.kernel.org/all/[email protected]/

The mddev kobject liftime is broken, now in the case del_work is queued, means mddev is about to be freed, meanwhile md_open can succeed.

Thanks,
Kuai

Quoted 224 lines

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-ced1b9e0.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/c709b0d9538c/vmlinux-ced1b9e0.xz
kernel image: https://storage.googleapis.com/syzbot-assets/129af0799fa3/bzImage-ced1b9e0.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:

Reported-by [email protected]

==================================================================

BUG: KASAN: slab-use-after-free in __list_add_valid_or_report+0x151/0x190 lib/list_debug.c:32
Read of size 8 at addr ffff888036fa1400 by task syz.2.1231/9834

CPU: 3 UID: 0 PID: 9834 Comm: syz.2.1231 Not tainted 6.16.0-syzkaller-00857-gced1b9e0392d #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
  <TASK>
  __dump_stack lib/dump_stack.c:94 [inline]
  dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
  print_address_description mm/kasan/report.c:378 [inline]
  print_report+0xcd/0x630 mm/kasan/report.c:482
  kasan_report+0xe0/0x110 mm/kasan/report.c:595
  __list_add_valid_or_report+0x151/0x190 lib/list_debug.c:32
  __list_add_valid include/linux/list.h:88 [inline]
  __list_add include/linux/list.h:150 [inline]
  list_add_tail include/linux/list.h:183 [inline]
  disk_add_events+0x90/0x170 block/disk-events.c:463
  add_disk_final block/genhd.c:427 [inline]
  add_disk_fwnode+0x3c8/0x5d0 block/genhd.c:610
  add_disk include/linux/blkdev.h:773 [inline]
  md_alloc+0x3c2/0x1080 drivers/md/md.c:5981
  md_alloc_and_put drivers/md/md.c:6016 [inline]
  md_probe drivers/md/md.c:6029 [inline]
  md_probe+0x6e/0xd0 drivers/md/md.c:6024
  blk_probe_dev+0x116/0x1a0 block/genhd.c:884
  blk_request_module+0x16/0xb0 block/genhd.c:897
  blkdev_get_no_open+0x9b/0x100 block/bdev.c:825
  blkdev_open+0x141/0x3f0 block/fops.c:684
  do_dentry_open+0x744/0x1c10 fs/open.c:965
  vfs_open+0x82/0x3f0 fs/open.c:1095
  do_open fs/namei.c:3887 [inline]
  path_openat+0x1de4/0x2cb0 fs/namei.c:4046
  do_filp_open+0x20b/0x470 fs/namei.c:4073
  do_sys_openat2+0x11b/0x1d0 fs/open.c:1435
  do_sys_open fs/open.c:1450 [inline]
  __do_sys_openat fs/open.c:1466 [inline]
  __se_sys_openat fs/open.c:1461 [inline]
  __x64_sys_openat+0x174/0x210 fs/open.c:1461
  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
  do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
  entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f4ea558e9a9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f4ea645e038 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f4ea57b6080 RCX: 00007f4ea558e9a9
RDX: 0000000000000000 RSI: 0000200000000a80 RDI: ffffffffffffff9c
RBP: 00007f4ea5610d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f4ea57b6080 R15: 00007fff25d53038
  </TASK>

Allocated by task 9822:
  kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
  kasan_save_track+0x14/0x30 mm/kasan/common.c:68
  poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
  __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:394
  kmalloc_noprof include/linux/slab.h:905 [inline]
  kzalloc_noprof include/linux/slab.h:1039 [inline]
  disk_alloc_events+0xf0/0x3f0 block/disk-events.c:439
  __add_disk+0x475/0xf00 block/genhd.c:500
  add_disk_fwnode+0x3f8/0x5d0 block/genhd.c:601
  add_disk include/linux/blkdev.h:773 [inline]
  md_alloc+0x3c2/0x1080 drivers/md/md.c:5981
  md_alloc_and_put drivers/md/md.c:6016 [inline]
  md_probe drivers/md/md.c:6029 [inline]
  md_probe+0x6e/0xd0 drivers/md/md.c:6024
  blk_probe_dev+0x116/0x1a0 block/genhd.c:884
  blk_request_module+0x16/0xb0 block/genhd.c:897
  blkdev_get_no_open+0x9b/0x100 block/bdev.c:825
  blkdev_open+0x141/0x3f0 block/fops.c:684
  do_dentry_open+0x744/0x1c10 fs/open.c:965
  vfs_open+0x82/0x3f0 fs/open.c:1095
  do_open fs/namei.c:3887 [inline]
  path_openat+0x1de4/0x2cb0 fs/namei.c:4046
  do_filp_open+0x20b/0x470 fs/namei.c:4073
  do_sys_openat2+0x11b/0x1d0 fs/open.c:1435
  do_sys_open fs/open.c:1450 [inline]
  __do_sys_openat fs/open.c:1466 [inline]
  __se_sys_openat fs/open.c:1461 [inline]
  __x64_sys_openat+0x174/0x210 fs/open.c:1461
  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
  do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
  entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 9817:
  kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
  kasan_save_track+0x14/0x30 mm/kasan/common.c:68
  kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:576
  poison_slab_object mm/kasan/common.c:247 [inline]
  __kasan_slab_free+0x51/0x70 mm/kasan/common.c:264
  kasan_slab_free include/linux/kasan.h:233 [inline]
  slab_free_hook mm/slub.c:2381 [inline]
  slab_free mm/slub.c:4643 [inline]
  kfree+0x2b4/0x4d0 mm/slub.c:4842
  disk_release+0x161/0x410 block/genhd.c:1301
  device_release+0xa1/0x240 drivers/base/core.c:2568
  kobject_cleanup lib/kobject.c:689 [inline]
  kobject_release lib/kobject.c:720 [inline]
  kref_put include/linux/kref.h:65 [inline]
  kobject_put+0x1e7/0x5a0 lib/kobject.c:737
  put_device+0x1f/0x30 drivers/base/core.c:3800
  blkdev_release+0x15/0x20 block/fops.c:699
  __fput+0x402/0xb70 fs/file_table.c:468
  task_work_run+0x14d/0x240 kernel/task_work.c:227
  resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
  exit_to_user_mode_loop+0xeb/0x110 kernel/entry/common.c:114
  exit_to_user_mode_prepare include/linux/entry-common.h:330 [inline]
  syscall_exit_to_user_mode_work include/linux/entry-common.h:414 [inline]
  syscall_exit_to_user_mode include/linux/entry-common.h:449 [inline]
  do_syscall_64+0x3f6/0x4c0 arch/x86/entry/syscall_64.c:100
  entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff888036fa1400
  which belongs to the cache kmalloc-512 of size 512

The buggy address is located 0 bytes inside of
freed 512-byte region [ffff888036fa1400, ffff888036fa1600)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x36fa0
head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88801b842c80 dead000000000100 dead000000000122
raw: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000

head: 00fff00000000040 ffff88801b842c80 dead000000000100 dead000000000122
head: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
head: 00fff00000000002 ffffea0000dbe801 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000004

page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 2, tgid 2 (kthreadd), ts 71482349709, free_ts 68765218476
  set_page_owner include/linux/page_owner.h:32 [inline]
  post_alloc_hook+0x1c0/0x230 mm/page_alloc.c:1704
  prep_new_page mm/page_alloc.c:1712 [inline]
  get_page_from_freelist+0x1321/0x3890 mm/page_alloc.c:3669
  __alloc_frozen_pages_noprof+0x261/0x23f0 mm/page_alloc.c:4959
  alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2419
  alloc_slab_page mm/slub.c:2451 [inline]
  allocate_slab mm/slub.c:2619 [inline]
  new_slab+0x23b/0x330 mm/slub.c:2673
  ___slab_alloc+0xd9c/0x1940 mm/slub.c:3859
  __slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3949
  __slab_alloc_node mm/slub.c:4024 [inline]
  slab_alloc_node mm/slub.c:4185 [inline]
  __kmalloc_cache_noprof+0xfb/0x3e0 mm/slub.c:4354
  kmalloc_noprof include/linux/slab.h:905 [inline]
  kzalloc_noprof include/linux/slab.h:1039 [inline]
  set_kthread_struct+0xcb/0x380 kernel/kthread.c:126
  copy_process+0x3107/0x7650 kernel/fork.c:2097
  kernel_clone+0xfc/0x960 kernel/fork.c:2599
  kernel_thread+0xd4/0x120 kernel/fork.c:2661
  create_kthread kernel/kthread.c:487 [inline]
  kthreadd+0x503/0x800 kernel/kthread.c:847
  ret_from_fork+0x5d4/0x6f0 arch/x86/kernel/process.c:148
  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
page last free pid 6016 tgid 6016 stack trace:
  reset_page_owner include/linux/page_owner.h:25 [inline]
  free_pages_prepare mm/page_alloc.c:1248 [inline]
  __free_frozen_pages+0x7fe/0x1180 mm/page_alloc.c:2706
  vfree+0x1fd/0xb50 mm/vmalloc.c:3434
  kcov_put kernel/kcov.c:439 [inline]
  kcov_put kernel/kcov.c:435 [inline]
  kcov_close+0x34/0x60 kernel/kcov.c:535
  __fput+0x402/0xb70 fs/file_table.c:468
  task_work_run+0x14d/0x240 kernel/task_work.c:227
  exit_task_work include/linux/task_work.h:40 [inline]
  do_exit+0x86c/0x2bd0 kernel/exit.c:964
  do_group_exit+0xd3/0x2a0 kernel/exit.c:1105
  get_signal+0x2673/0x26d0 kernel/signal.c:3034
  arch_do_signal_or_restart+0x8f/0x7d0 arch/x86/kernel/signal.c:337
  exit_to_user_mode_loop+0x84/0x110 kernel/entry/common.c:111
  exit_to_user_mode_prepare include/linux/entry-common.h:330 [inline]
  syscall_exit_to_user_mode_work include/linux/entry-common.h:414 [inline]
  syscall_exit_to_user_mode include/linux/entry-common.h:449 [inline]
  do_syscall_64+0x3f6/0x4c0 arch/x86/entry/syscall_64.c:100
  entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
  ffff888036fa1300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
  ffff888036fa1380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
Quoted 1 line

ffff888036fa1400: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

                    ^

ffff888036fa1480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888036fa1500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

---
This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at [email protected].

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If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

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#syz undup

.

#6 lore raw
Quoted 1 line · Yu Kuai

+CC Xiao

Forgot to CC in the last emial, sorry for the noisy.

Thanks,
Kuai

Quoted 256 lines · syzbot
Quoted 4 lines

Hello,

syzbot found the following issue on:

Quoted 9 lines

HEAD commit:    ced1b9e0392d Merge tag 'ata-6.17-rc1' of git://git.kernel...
git tree:       upstream

console output: https://syzkaller.appspot.com/x/log.txt?x=133b8cf0580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=52c12ce9080f644c
dashboard link: https://syzkaller.appspot.com/bug?extid=fa3a12519f0d3fd4ec16

compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=154b31bc580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=171a9782580000

This looks like the same cause with another report:

https://lore.kernel.org/all/[email protected]/

The mddev kobject liftime is broken, now in the case del_work is queued, means mddev is about to be freed, meanwhile md_open can succeed.

Thanks,
Kuai

Quoted 218 lines

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-ced1b9e0.raw.xz

vmlinux: https://storage.googleapis.com/syzbot-assets/c709b0d9538c/vmlinux-ced1b9e0.xz

kernel image: https://storage.googleapis.com/syzbot-assets/129af0799fa3/bzImage-ced1b9e0.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:

Reported-by [email protected]

==================================================================

BUG: KASAN: slab-use-after-free in __list_add_valid_or_report+0x151/0x190 lib/list_debug.c:32
Read of size 8 at addr ffff888036fa1400 by task syz.2.1231/9834

CPU: 3 UID: 0 PID: 9834 Comm: syz.2.1231 Not tainted 6.16.0-syzkaller-00857-gced1b9e0392d #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
  <TASK>
  __dump_stack lib/dump_stack.c:94 [inline]
  dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
  print_address_description mm/kasan/report.c:378 [inline]
  print_report+0xcd/0x630 mm/kasan/report.c:482
  kasan_report+0xe0/0x110 mm/kasan/report.c:595
  __list_add_valid_or_report+0x151/0x190 lib/list_debug.c:32
  __list_add_valid include/linux/list.h:88 [inline]
  __list_add include/linux/list.h:150 [inline]
  list_add_tail include/linux/list.h:183 [inline]
  disk_add_events+0x90/0x170 block/disk-events.c:463
  add_disk_final block/genhd.c:427 [inline]
  add_disk_fwnode+0x3c8/0x5d0 block/genhd.c:610
  add_disk include/linux/blkdev.h:773 [inline]
  md_alloc+0x3c2/0x1080 drivers/md/md.c:5981
  md_alloc_and_put drivers/md/md.c:6016 [inline]
  md_probe drivers/md/md.c:6029 [inline]
  md_probe+0x6e/0xd0 drivers/md/md.c:6024
  blk_probe_dev+0x116/0x1a0 block/genhd.c:884
  blk_request_module+0x16/0xb0 block/genhd.c:897
  blkdev_get_no_open+0x9b/0x100 block/bdev.c:825
  blkdev_open+0x141/0x3f0 block/fops.c:684
  do_dentry_open+0x744/0x1c10 fs/open.c:965
  vfs_open+0x82/0x3f0 fs/open.c:1095
  do_open fs/namei.c:3887 [inline]
  path_openat+0x1de4/0x2cb0 fs/namei.c:4046
  do_filp_open+0x20b/0x470 fs/namei.c:4073
  do_sys_openat2+0x11b/0x1d0 fs/open.c:1435
  do_sys_open fs/open.c:1450 [inline]
  __do_sys_openat fs/open.c:1466 [inline]
  __se_sys_openat fs/open.c:1461 [inline]
  __x64_sys_openat+0x174/0x210 fs/open.c:1461
  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
  do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
  entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f4ea558e9a9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f4ea645e038 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f4ea57b6080 RCX: 00007f4ea558e9a9
RDX: 0000000000000000 RSI: 0000200000000a80 RDI: ffffffffffffff9c
RBP: 00007f4ea5610d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f4ea57b6080 R15: 00007fff25d53038
  </TASK>

Allocated by task 9822:
  kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
  kasan_save_track+0x14/0x30 mm/kasan/common.c:68
  poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
  __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:394
  kmalloc_noprof include/linux/slab.h:905 [inline]
  kzalloc_noprof include/linux/slab.h:1039 [inline]
  disk_alloc_events+0xf0/0x3f0 block/disk-events.c:439
  __add_disk+0x475/0xf00 block/genhd.c:500
  add_disk_fwnode+0x3f8/0x5d0 block/genhd.c:601
  add_disk include/linux/blkdev.h:773 [inline]
  md_alloc+0x3c2/0x1080 drivers/md/md.c:5981
  md_alloc_and_put drivers/md/md.c:6016 [inline]
  md_probe drivers/md/md.c:6029 [inline]
  md_probe+0x6e/0xd0 drivers/md/md.c:6024
  blk_probe_dev+0x116/0x1a0 block/genhd.c:884
  blk_request_module+0x16/0xb0 block/genhd.c:897
  blkdev_get_no_open+0x9b/0x100 block/bdev.c:825
  blkdev_open+0x141/0x3f0 block/fops.c:684
  do_dentry_open+0x744/0x1c10 fs/open.c:965
  vfs_open+0x82/0x3f0 fs/open.c:1095
  do_open fs/namei.c:3887 [inline]
  path_openat+0x1de4/0x2cb0 fs/namei.c:4046
  do_filp_open+0x20b/0x470 fs/namei.c:4073
  do_sys_openat2+0x11b/0x1d0 fs/open.c:1435
  do_sys_open fs/open.c:1450 [inline]
  __do_sys_openat fs/open.c:1466 [inline]
  __se_sys_openat fs/open.c:1461 [inline]
  __x64_sys_openat+0x174/0x210 fs/open.c:1461
  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
  do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
  entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 9817:
  kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
  kasan_save_track+0x14/0x30 mm/kasan/common.c:68
  kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:576
  poison_slab_object mm/kasan/common.c:247 [inline]
  __kasan_slab_free+0x51/0x70 mm/kasan/common.c:264
  kasan_slab_free include/linux/kasan.h:233 [inline]
  slab_free_hook mm/slub.c:2381 [inline]
  slab_free mm/slub.c:4643 [inline]
  kfree+0x2b4/0x4d0 mm/slub.c:4842
  disk_release+0x161/0x410 block/genhd.c:1301
  device_release+0xa1/0x240 drivers/base/core.c:2568
  kobject_cleanup lib/kobject.c:689 [inline]
  kobject_release lib/kobject.c:720 [inline]
  kref_put include/linux/kref.h:65 [inline]
  kobject_put+0x1e7/0x5a0 lib/kobject.c:737
  put_device+0x1f/0x30 drivers/base/core.c:3800
  blkdev_release+0x15/0x20 block/fops.c:699
  __fput+0x402/0xb70 fs/file_table.c:468
  task_work_run+0x14d/0x240 kernel/task_work.c:227
  resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
  exit_to_user_mode_loop+0xeb/0x110 kernel/entry/common.c:114
  exit_to_user_mode_prepare include/linux/entry-common.h:330 [inline]
  syscall_exit_to_user_mode_work include/linux/entry-common.h:414 [inline]
  syscall_exit_to_user_mode include/linux/entry-common.h:449 [inline]
  do_syscall_64+0x3f6/0x4c0 arch/x86/entry/syscall_64.c:100
  entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff888036fa1400

  which belongs to the cache kmalloc-512 of size 512 The buggy address is located 0 bytes inside of freed 512-byte region [ffff888036fa1400, ffff888036fa1600)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x36fa0
head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88801b842c80 dead000000000100 dead000000000122
raw: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000

head: 00fff00000000040 ffff88801b842c80 dead000000000100 dead000000000122
head: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
head: 00fff00000000002 ffffea0000dbe801 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000004

page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 2, tgid 2 (kthreadd), ts 71482349709, free_ts 68765218476
  set_page_owner include/linux/page_owner.h:32 [inline]
  post_alloc_hook+0x1c0/0x230 mm/page_alloc.c:1704
  prep_new_page mm/page_alloc.c:1712 [inline]
  get_page_from_freelist+0x1321/0x3890 mm/page_alloc.c:3669
  __alloc_frozen_pages_noprof+0x261/0x23f0 mm/page_alloc.c:4959
  alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2419
  alloc_slab_page mm/slub.c:2451 [inline]
  allocate_slab mm/slub.c:2619 [inline]
  new_slab+0x23b/0x330 mm/slub.c:2673
  ___slab_alloc+0xd9c/0x1940 mm/slub.c:3859
  __slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3949
  __slab_alloc_node mm/slub.c:4024 [inline]
  slab_alloc_node mm/slub.c:4185 [inline]
  __kmalloc_cache_noprof+0xfb/0x3e0 mm/slub.c:4354
  kmalloc_noprof include/linux/slab.h:905 [inline]
  kzalloc_noprof include/linux/slab.h:1039 [inline]
  set_kthread_struct+0xcb/0x380 kernel/kthread.c:126
  copy_process+0x3107/0x7650 kernel/fork.c:2097
  kernel_clone+0xfc/0x960 kernel/fork.c:2599
  kernel_thread+0xd4/0x120 kernel/fork.c:2661
  create_kthread kernel/kthread.c:487 [inline]
  kthreadd+0x503/0x800 kernel/kthread.c:847
  ret_from_fork+0x5d4/0x6f0 arch/x86/kernel/process.c:148
  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
page last free pid 6016 tgid 6016 stack trace:
  reset_page_owner include/linux/page_owner.h:25 [inline]
  free_pages_prepare mm/page_alloc.c:1248 [inline]
  __free_frozen_pages+0x7fe/0x1180 mm/page_alloc.c:2706
  vfree+0x1fd/0xb50 mm/vmalloc.c:3434
  kcov_put kernel/kcov.c:439 [inline]
  kcov_put kernel/kcov.c:435 [inline]
  kcov_close+0x34/0x60 kernel/kcov.c:535
  __fput+0x402/0xb70 fs/file_table.c:468
  task_work_run+0x14d/0x240 kernel/task_work.c:227
  exit_task_work include/linux/task_work.h:40 [inline]
  do_exit+0x86c/0x2bd0 kernel/exit.c:964
  do_group_exit+0xd3/0x2a0 kernel/exit.c:1105
  get_signal+0x2673/0x26d0 kernel/signal.c:3034
  arch_do_signal_or_restart+0x8f/0x7d0 arch/x86/kernel/signal.c:337
  exit_to_user_mode_loop+0x84/0x110 kernel/entry/common.c:111
  exit_to_user_mode_prepare include/linux/entry-common.h:330 [inline]
  syscall_exit_to_user_mode_work include/linux/entry-common.h:414 [inline]
  syscall_exit_to_user_mode include/linux/entry-common.h:449 [inline]
  do_syscall_64+0x3f6/0x4c0 arch/x86/entry/syscall_64.c:100
  entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
  ffff888036fa1300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
  ffff888036fa1380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
Quoted 1 line

ffff888036fa1400: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

                    ^
  ffff888036fa1480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
  ffff888036fa1500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

---
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Quoted 9 lines

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