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general protection fault in nilfs_clear_dirty_page

syzbot Applied syzbot 3 participants 6 messages Oct 22, 2022 – Jun 12, 2023

Subsystems (3)
VFS Block layer NILFS2 filesystem
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syzbot

author syzbot
#0 lore raw

Hello,

syzbot found the following issue on:

HEAD commit:    6d36c728bc2e Merge tag 'net-6.1-rc2' of git://git.kernel.o..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1526d2e2880000
kernel config:  https://syzkaller.appspot.com/x/.config?x=afc317c0f52ce670
dashboard link: https://syzkaller.appspot.com/bug?extid=53369d11851d8f26735c
compiler:       Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a2030ff47985/disk-6d36c728.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/82a6ec6fd4db/vmlinux-6d36c728.xz

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

Reported-by syzbot+53369d11851d8f26735c-Pl5Pbv+GP7P466ipTTIvnc23WoclnBCfAL8bYrjMMd8@public.gmane.org

NILFS (loop4): discard dirty block: blocknr=0, size=1024 NILFS (loop4): discard dirty block: blocknr=0, size=1024 NILFS (loop4): discard dirty block: blocknr=0, size=1024 NILFS (loop4): discard dirty block: blocknr=0, size=1024

general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 1 PID: 5633 Comm: kworker/u4:11 Not tainted 6.1.0-rc1-syzkaller-00093-g6d36c728bc2e #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/11/2022
Workqueue: writeback wb_workfn (flush-7:4)
RIP: 0010:nilfs_clear_dirty_page+0x9a/0x1080 fs/nilfs2/page.c:387
Code: 31 e8 9a b3 3c fe 49 8d 5f 18 48 89 d8 48 c1 e8 03 42 80 3c 30 00 74 08 48 89 df e8 e0 9c 90 fe 48 8b 1b 48 89 d8 48 c1 e8 03 <42> 80 3c 30 00 74 08 48 89 df e8 c7 9c 90 fe 4c 8b 2b 49 8d 5d 28
RSP: 0018:ffffc900053e7020 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff888026a08000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffea00020d3440
RBP: ffffc900053e70f0 R08: ffffffff834ae92a R09: fffff9400041a689
R10: fffff9400041a689 R11: 1ffffd400041a688 R12: 000000000000000e
R13: 0000000000000000 R14: dffffc0000000000 R15: ffffea00020d3440
FS:  0000000000000000(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f592433f000 CR3: 0000000033285000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 nilfs_clear_dirty_pages+0x1d9/0x380 fs/nilfs2/page.c:372
 nilfs_writepages+0x117/0x150 fs/nilfs2/inode.c:165
 do_writepages+0x3c3/0x680 mm/page-writeback.c:2469
 __writeback_single_inode+0xd1/0x670 fs/fs-writeback.c:1587
 writeback_sb_inodes+0xb3b/0x18f0 fs/fs-writeback.c:1870
 __writeback_inodes_wb+0x125/0x420 fs/fs-writeback.c:1941
 wb_writeback+0x440/0x7b0 fs/fs-writeback.c:2046
 wb_check_start_all fs/fs-writeback.c:2168 [inline]
 wb_do_writeback fs/fs-writeback.c:2194 [inline]
 wb_workfn+0x827/0xef0 fs/fs-writeback.c:2227
 process_one_work+0x877/0xdb0 kernel/workqueue.c:2289
 worker_thread+0xb14/0x1330 kernel/workqueue.c:2436
 kthread+0x266/0x300 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:nilfs_clear_dirty_page+0x9a/0x1080 fs/nilfs2/page.c:387
Code: 31 e8 9a b3 3c fe 49 8d 5f 18 48 89 d8 48 c1 e8 03 42 80 3c 30 00 74 08 48 89 df e8 e0 9c 90 fe 48 8b 1b 48 89 d8 48 c1 e8 03 <42> 80 3c 30 00 74 08 48 89 df e8 c7 9c 90 fe 4c 8b 2b 49 8d 5d 28
RSP: 0018:ffffc900053e7020 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff888026a08000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffea00020d3440
RBP: ffffc900053e70f0 R08: ffffffff834ae92a R09: fffff9400041a689
R10: fffff9400041a689 R11: 1ffffd400041a688 R12: 000000000000000e
R13: 0000000000000000 R14: dffffc0000000000 R15: ffffea00020d3440
FS:  0000000000000000(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c000074368 CR3: 000000007ef36000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess), 1 bytes skipped:
   0:	e8 9a b3 3c fe       	callq  0xfe3cb39f
   5:	49 8d 5f 18          	lea    0x18(%r15),%rbx
   9:	48 89 d8             	mov    %rbx,%rax
   c:	48 c1 e8 03          	shr    $0x3,%rax
  10:	42 80 3c 30 00       	cmpb   $0x0,(%rax,%r14,1)
  15:	74 08                	je     0x1f
  17:	48 89 df             	mov    %rbx,%rdi
  1a:	e8 e0 9c 90 fe       	callq  0xfe909cff
  1f:	48 8b 1b             	mov    (%rbx),%rbx
  22:	48 89 d8             	mov    %rbx,%rax
  25:	48 c1 e8 03          	shr    $0x3,%rax
* 29:	42 80 3c 30 00       	cmpb   $0x0,(%rax,%r14,1) <-- trapping instruction
  2e:	74 08                	je     0x38
  30:	48 89 df             	mov    %rbx,%rdi
  33:	e8 c7 9c 90 fe       	callq  0xfe909cff
  38:	4c 8b 2b             	mov    (%rbx),%r13
  3b:	49 8d 5d 28          	lea    0x28(%r13),%rbx

---
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 syzkaller-/JYPxA39Uh5TLH3MbocFF+G/[email protected]

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

author syzbot
#1 lore raw
syzbot has found a reproducer for the following issue on:

syzbot has found a reproducer for the following issue on:

HEAD commit:    022ce8862dff Merge tag 'i2c-for-6.4-rc6' of git://git.kern..
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=118151dd280000
kernel config:  https://syzkaller.appspot.com/x/.config?x=7474de833c217bf4
dashboard link: https://syzkaller.appspot.com/bug?extid=53369d11851d8f26735c
compiler:       Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=13e9d48b280000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=12d7fa63280000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/cb6ca005422c/disk-022ce886.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/172bf908a89e/vmlinux-022ce886.xz
kernel image: https://storage.googleapis.com/syzbot-assets/4a00b7ed8430/bzImage-022ce886.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/edff56b4a75d/mount_0.gz

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

Reported-by syzbot+53369d11851d8f26735c-Pl5Pbv+GP7P466ipTTIvnc23WoclnBCfAL8bYrjMMd8@public.gmane.org
general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 0 PID: 5040 Comm: syz-executor116 Not tainted 6.4.0-rc5-syzkaller-00305-g022ce8862dff #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/25/2023
RIP: 0010:nilfs_clear_dirty_page+0xa9/0x1130 fs/nilfs2/page.c:388
Code: 48 89 d8 48 c1 e8 03 42 80 3c 30 00 74 08 48 89 df e8 1b 38 97 fe 48 8b 1b 48 89 d8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 48 89 df e8 f9 37 97 fe 4c 8b 2b 49 8d 5d 28 48
RSP: 0018:ffffc90003d2f2e0 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffea0001cb1900
RBP: ffffc90003d2f3b0 R08: ffffffff834bef29 R09: fffff94000396321
R10: 0000000000000000 R11: dffffc0000000001 R12: ffffea0001cb1900
R13: 0000000000000000 R14: dffffc0000000000 R15: dffffc0000000000
FS:  00007f996874e700(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055fe30356e00 CR3: 000000002995d000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 nilfs_clear_dirty_pages+0x1e0/0x370 fs/nilfs2/page.c:373
 nilfs_writepages+0x11c/0x160 fs/nilfs2/inode.c:165
 do_writepages+0x3a6/0x670 mm/page-writeback.c:2551
 filemap_fdatawrite_wbc+0x125/0x180 mm/filemap.c:390
 __filemap_fdatawrite_range mm/filemap.c:423 [inline]
 filemap_write_and_wait_range+0x1d4/0x2c0 mm/filemap.c:678
 generic_file_read_iter+0x19e/0x540 mm/filemap.c:2805
 call_read_iter include/linux/fs.h:1862 [inline]
 generic_file_splice_read+0x240/0x640 fs/splice.c:419
 do_splice_to fs/splice.c:902 [inline]
 splice_direct_to_actor+0x40c/0xbd0 fs/splice.c:973
 do_splice_direct+0x283/0x3d0 fs/splice.c:1082
 do_sendfile+0x620/0xff0 fs/read_write.c:1254
 __do_sys_sendfile64 fs/read_write.c:1322 [inline]
 __se_sys_sendfile64+0x17c/0x1e0 fs/read_write.c:1308
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f9970ac36f9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 71 15 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f996874e2f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f9970b497b0 RCX: 00007f9970ac36f9
RDX: 0000000000000000 RSI: 0000000000000008 RDI: 0000000000000007
RBP: 00007f9970b15b1c R08: 0000000000000000 R09: 0000000000000000
R10: 0001000000201005 R11: 0000000000000246 R12: 00007f9970b150c0
R13: 00000000200026c0 R14: 0032656c69662f2e R15: 00007f9970b497b8
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:nilfs_clear_dirty_page+0xa9/0x1130 fs/nilfs2/page.c:388
Code: 48 89 d8 48 c1 e8 03 42 80 3c 30 00 74 08 48 89 df e8 1b 38 97 fe 48 8b 1b 48 89 d8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 48 89 df e8 f9 37 97 fe 4c 8b 2b 49 8d 5d 28 48
RSP: 0018:ffffc90003d2f2e0 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffea0001cb1900
RBP: ffffc90003d2f3b0 R08: ffffffff834bef29 R09: fffff94000396321
R10: 0000000000000000 R11: dffffc0000000001 R12: ffffea0001cb1900
R13: 0000000000000000 R14: dffffc0000000000 R15: dffffc0000000000
FS:  00007f996874e700(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f9970b1500a CR3: 000000002995d000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	48 89 d8             	mov    %rbx,%rax
   3:	48 c1 e8 03          	shr    $0x3,%rax
   7:	42 80 3c 30 00       	cmpb   $0x0,(%rax,%r14,1)
   c:	74 08                	je     0x16
   e:	48 89 df             	mov    %rbx,%rdi
  11:	e8 1b 38 97 fe       	callq  0xfe973831
  16:	48 8b 1b             	mov    (%rbx),%rbx
  19:	48 89 d8             	mov    %rbx,%rax
  1c:	48 c1 e8 03          	shr    $0x3,%rax
  20:	48 b9 00 00 00 00 00 	movabs $0xdffffc0000000000,%rcx
  27:	fc ff df
* 2a:	80 3c 08 00          	cmpb   $0x0,(%rax,%rcx,1) <-- trapping instruction
  2e:	74 08                	je     0x38
  30:	48 89 df             	mov    %rbx,%rdi
  33:	e8 f9 37 97 fe       	callq  0xfe973831
  38:	4c 8b 2b             	mov    (%rbx),%r13
  3b:	49 8d 5d 28          	lea    0x28(%r13),%rbx
  3f:	48                   	rex.W

---
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.

author syzbot
#2 lore raw
In reply to syzbot
syzbot has bisected this issue to:

syzbot has bisected this issue to:

commit 4a445b7b6178d88956192c0202463063f52e8667

Author: Qu Wenruo <[email protected]>
Date:   Sat Aug 13 08:06:53 2022 +0000

btrfs: don't merge pages into bio if their page offset is not contiguous

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=17778475280000
start commit:   022ce8862dff Merge tag 'i2c-for-6.4-rc6' of git://git.kern..
git tree:       upstream
final oops:     https://syzkaller.appspot.com/x/report.txt?x=14f78475280000
console output: https://syzkaller.appspot.com/x/log.txt?x=10f78475280000
kernel config:  https://syzkaller.appspot.com/x/.config?x=7474de833c217bf4
dashboard link: https://syzkaller.appspot.com/bug?extid=53369d11851d8f26735c
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=13e9d48b280000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=12d7fa63280000
Reported-by [email protected]
Fixes 4a445b7b6178 ("btrfs: don't merge pages into bio if their page offset is not contiguous")

For information about bisection process see: https://goo.gl/tpsmEJ#bisection

#3 lore raw
Quoted 7 lines · syzbot

syzbot has bisected this issue to:

commit 4a445b7b6178d88956192c0202463063f52e8667

Author: Qu Wenruo <wqu-IBi9RG/[email protected]>
Date:   Sat Aug 13 08:06:53 2022 +0000

btrfs: don't merge pages into bio if their page offset is not contiguous

I can't see how that btrfs commit would affect nilfs2..

maintainer
#4 lore raw
Quoted 11 lines · On Mon, Jun 12, 2023 at 12:30 PM Christoph Hellwig wrote:
Quoted 7 lines · syzbot

syzbot has bisected this issue to:

commit 4a445b7b6178d88956192c0202463063f52e8667

Author: Qu Wenruo <wqu-IBi9RG/[email protected]>
Date:   Sat Aug 13 08:06:53 2022 +0000

btrfs: don't merge pages into bio if their page offset is not contiguous

I can't see how that btrfs commit would affect nilfs2..

Yeah, I think this bisection result is wrong.
I have already posted a bug-fix patch titled "nilfs2: prevent general protection fault in nilfs_clear_dirty_page()"
for this issue.

Thanks,
Ryusuke Konishi

maintainer
#5 lore raw

PATCH 1/1 nilfs2: prevent general protection fault in nilfs_clear_dirty_page()

In reply to syzbot

In a syzbot stress test that deliberately causes file system errors on nilfs2 with a corrupted disk image, it has been reported that nilfs_clear_dirty_page() called from nilfs_clear_dirty_pages() can cause a general protection fault.

In nilfs_clear_dirty_pages(), when looking up dirty pages from the page cache and calling nilfs_clear_dirty_page() for each dirty page/folio retrieved, the back reference from the argument page to "mapping" may have been changed to NULL (and possibly others). It is necessary to check this after locking the page/folio.

So, fix this issue by not calling nilfs_clear_dirty_page() on a page/folio after locking it in nilfs_clear_dirty_pages() if the back reference "mapping" from the page/folio is different from the "mapping" that held the page/folio just before.

Signed-off-by Ryusuke Konishi <[email protected]>
Reported-by [email protected]
Closes https://lkml.kernel.org/r/[email protected] open here
Tested-by Ryusuke Konishi <[email protected]>
Cc [email protected]
---
 fs/nilfs2/page.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)
fs/nilfs2/page.c +9 -1
index 5cf30827f244..b4e54d079b7d 100644
@@ -370,7 +370,15 @@ void nilfs_clear_dirty_pages(struct address_space *mapping, bool silent)
 			struct folio *folio = fbatch.folios[i];
 
 			folio_lock(folio);
-			nilfs_clear_dirty_page(&folio->page, silent);
+
+			/*
+			 * This folio may have been removed from the address
+			 * space by truncation or invalidation when the lock
+			 * was acquired.  Skip processing in that case.
+			 */
+			if (likely(folio->mapping == mapping))
+				nilfs_clear_dirty_page(&folio->page, silent);
+
 			folio_unlock(folio);
 		}
 		folio_batch_release(&fbatch);
Signature · 1 line
2.34.1