Skip to contentSkip to conversation

BUG: unable to handle kernel NULL pointer dereference in snd_ctl_led_get

syzbot syzbot 2 participants 5 messages Aug 27 Sound

lore
Share & tools
lore

syzbot

author syzbot
#0 lore raw

Hello,

syzbot found the following issue on:

HEAD commit:    818bebeb63dd drm/xe: Don't hand out the flat CCS storage a..
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=12a3d579580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=ccca94d2c01b9e78
dashboard link: https://syzkaller.appspot.com/bug?extid=b7fe2760ea6f1ee44b4d
compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=178bb415580000

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

Reported-by [email protected]
BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor instruction fetch in kernel mode
#PF: error_code(0x0010) - not-present page
PGD 0 P4D 0 
Oops: Oops: 0010 [#1] SMP KASAN NOPTI
CPU: 2 UID: 0 PID: 6042 Comm: syz-executor129 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:0x0
Code: Unable to access opcode bytes at 0xffffffffffffffd6.
RSP: 0018:ffffc900034b7948 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff88802e2ff400 RCX: 0000000000000000
RDX: 1ffff11005c5fe8c RSI: ffffffff9bda4620 RDI: ffff88802e2ff400
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
R10: ffffffff9bda4620 R11: 0000000000000000 R12: 0000000000000000
R13: ffffffff90b73bc8 R14: ffff88802e2ff400 R15: ffffffff90b73bc8
FS:  000055555669f400(0000) GS:ffff8880d5da2000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 0000000027234000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 snd_ctl_led_get+0x231/0x430 sound/core/control_led.c:122
 snd_ctl_led_set_state+0x5c1/0x7f0 sound/core/control_led.c:168
 snd_ctl_led_notify+0x15b/0x1e0 sound/core/control_led.c:239
 snd_ctl_led_set_id sound/core/control_led.c:268 [inline]
 set_led_id+0xb0f/0xe80 sound/core/control_led.c:557
 dev_attr_store+0x58/0x80 drivers/base/core.c:2509
 sysfs_kf_write+0xf2/0x150 fs/sysfs/file.c:145
 kernfs_fop_write_iter+0x3e0/0x5f0 fs/kernfs/file.c:345
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x6af/0x1050 fs/read_write.c:687
 ksys_write+0x12a/0x250 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa7e64de2b7
Code: 48 89 fa 4c 89 df e8 98 1d 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff
RSP: 002b:00007ffe15525110 EFLAGS: 00000202 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 000055555669f400 RCX: 00007fa7e64de2b7
RDX: 0000000000000002 RSI: 00007ffe155251a0 RDI: 0000000000000004
RBP: 0000000000000004 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 00007ffe155251a0
R13: 00007fa7e6517024 R14: 00007fa7e6541cc0 R15: 0000000000000002
 </TASK>
Modules linked in:
CR2: 0000000000000000
---[ end trace 0000000000000000 ]---
RIP: 0010:0x0
Code: Unable to access opcode bytes at 0xffffffffffffffd6.
RSP: 0018:ffffc900034b7948 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff88802e2ff400 RCX: 0000000000000000
RDX: 1ffff11005c5fe8c RSI: ffffffff9bda4620 RDI: ffff88802e2ff400
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
R10: ffffffff9bda4620 R11: 0000000000000000 R12: 0000000000000000
R13: ffffffff90b73bc8 R14: ffff88802e2ff400 R15: ffffffff90b73bc8
FS:  000055555669f400(0000) GS:ffff8880d5da2000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 0000000027234000 CR4: 0000000000352ef0

---
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

#syz test: upstream 818bebeb63dd

sound/core/control_led.c +2 -4
index 8cbacee57ce7..f6a46ed97d37 100644
@@ -114,13 +114,11 @@ static int snd_ctl_led_get(struct snd_ctl_led_ctl *lctl)
        info.id = kctl->id;
        info.id.index += lctl->index_offset;
        info.id.numid += lctl->index_offset;
-       result = kctl->info(kctl, &info);
-       if (result < 0)
+       if (!kctl->info || kctl->info(kctl, &info)
                return -1;
        memset(&value, 0, sizeof(value));
        value.id = info.id;
-       result = kctl->get(kctl, &value);
-       if (result < 0)
+       if (!kctl->get || kctl->get(kctl, &value))
                return -1;
        if (info.type == SNDRV_CTL_ELEM_TYPE_BOOLEAN ||
            info.type == SNDRV_CTL_ELEM_TYPE_INTEGER) {
author syzbot
#2 lore raw
syzbot tried to test the proposed patch but the build/boot failed:

Hello,

syzbot tried to test the proposed patch but the build/boot failed:

sound/core/control_led.c:117:50: error: expected ')' before 'return' sound/core/control_led.c:134:1: error: expected expression before '}' token sound/core/control_led.c:134:1: error: no return statement in function returning non-void [-Werror=return-type]

Tested on:

commit:         818bebeb drm/xe: Don't hand out the flat CCS storage a..
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel config:  https://syzkaller.appspot.com/x/.config?x=ccca94d2c01b9e78
dashboard link: https://syzkaller.appspot.com/bug?extid=b7fe2760ea6f1ee44b4d
compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
patch:          https://syzkaller.appspot.com/x/patch.diff?x=11abd579580000
#3 lore raw
In reply to syzbot

#syz test: upstream 818bebeb63dd

sound/core/control_led.c +2 -4
index 8cbacee57ce7..f6a46ed97d37 100644
@@ -114,13 +114,11 @@ static int snd_ctl_led_get(struct snd_ctl_led_ctl *lctl)
        info.id = kctl->id;
        info.id.index += lctl->index_offset;
        info.id.numid += lctl->index_offset;
-       result = kctl->info(kctl, &info);
-       if (result < 0)
+       if (!kctl->info || kctl->info(kctl, &info))
                return -1;
        memset(&value, 0, sizeof(value));
        value.id = info.id;
-       result = kctl->get(kctl, &value);
-       if (result < 0)
+       if (!kctl->get || kctl->get(kctl, &value))
                return -1;
        if (info.type == SNDRV_CTL_ELEM_TYPE_BOOLEAN ||
            info.type == SNDRV_CTL_ELEM_TYPE_INTEGER) {
author syzbot Tested-by
#4 lore raw
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:         818bebeb drm/xe: Don't hand out the flat CCS storage a..
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=16e14579580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=ccca94d2c01b9e78
dashboard link: https://syzkaller.appspot.com/bug?extid=b7fe2760ea6f1ee44b4d
compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
patch:          https://syzkaller.appspot.com/x/patch.diff?x=1714e579580000

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