From: syzbot <syzbot+54648a6c1187a7ef46a6@syzkaller.appspotmail.com>
To: kartikey406@gmail.com, linux-kernel@vger.kernel.org,
syzkaller-bugs@googlegroups.com
Subject: Re: [syzbot] [media?] [usb?] KASAN: slab-use-after-free Read in dev_dbg_obj
Date: Mon, 02 Nov 2026 03:25:05 -0800 [thread overview]
Message-ID: <6ae87311.64e51036.15cf6a.0024.GAE@google.com> (raw)
In-Reply-To: <20261102103745.7043-1-kartikey406@gmail.com>
Hello,
syzbot has tested the proposed patch but the reproducer is still triggering an issue:
general protection fault in v4l2_open
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000019: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x00000000000000c8-0x00000000000000cf]
CPU: 3 UID: 0 PID: 7485 Comm: v4l_id 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:kasan_byte_accessible+0x15/0x30 mm/kasan/generic.c:210
Code: 00 00 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f 40 d6 48 b8 00 00 00 00 00 fc ff df 48 c1 ef 03 48 01 c7 <0f> b6 07 3c 07 0f 96 c0 e9 8e 5f 68 09 66 66 2e 0f 1f 84 00 00 00
RSP: 0018:ffffc90007d076a0 EFLAGS: 00010082
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff8bee97ca RDI: dffffc0000000019
RBP: 00000000000000c8 R08: 0000000000000001 R09: 0000000000000000
R10: ffffffff926ad55f R11: 0000000000000000 R12: ffffffff8bee97ca
R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000000
FS: 00007f20dbb46880(0000) GS:ffff888095581000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005571aa07b64d CR3: 000000006d254000 CR4: 0000000000352ef0
Call Trace:
<TASK>
__kasan_check_byte+0x13/0x50 mm/kasan/common.c:584
kasan_check_byte include/linux/kasan.h:402 [inline]
lock_acquire kernel/locking/lockdep.c:5916 [inline]
lock_acquire+0x132/0x380 kernel/locking/lockdep.c:5899
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:155 [inline]
_raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:181
ida_free+0xd3/0x2f0 lib/idr.c:566
__media_device_unregister_entity+0x70/0x2f0 drivers/media/mc/mc-device.c:582
media_device_unregister_entity+0x4b/0x70 drivers/media/mc/mc-device.c:677
v4l2_device_release+0x363/0x480 drivers/media/v4l2-core/v4l2-dev.c:208
device_release+0xd2/0x270 drivers/base/core.c:2640
kobject_cleanup lib/kobject.c:689 [inline]
kobject_release lib/kobject.c:720 [inline]
kref_put include/linux/kref.h:65 [inline]
kobject_put+0x1f7/0x640 lib/kobject.c:737
put_device+0x1f/0x30 drivers/base/core.c:3886
video_put drivers/media/v4l2-core/v4l2-dev.c:173 [inline]
v4l2_open+0x2e5/0x490 drivers/media/v4l2-core/v4l2-dev.c:450
chrdev_open+0x234/0x6a0 fs/char_dev.c:413
do_dentry_open+0x674/0x1470 fs/open.c:1000
vfs_open_consume+0xcc/0x460 fs/open.c:1131
do_open fs/namei.c:4851 [inline]
path_openat+0x1547/0x23f0 fs/namei.c:5016
do_file_open+0x20e/0x430 fs/namei.c:5045
do_sys_openat2+0x163/0x1d0 fs/open.c:1442
do_sys_open fs/open.c:1448 [inline]
__do_sys_openat fs/open.c:1464 [inline]
__se_sys_openat fs/open.c:1459 [inline]
__x64_sys_openat+0x12d/0x210 fs/open.c:1459
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x121/0x770 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f20dbbd2407
Code: 48 89 fa 4c 89 df e8 38 aa 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:00007ffd59333bc0 EFLAGS: 00000202 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f20dbb46880 RCX: 00007f20dbbd2407
RDX: 0000000000000000 RSI: 00007ffd59335f1d RDI: ffffffffffffff9c
RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000
R13: 00007ffd59333e10 R14: 00007f20dbe2b000 R15: 00005571aa07f4d8
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:kasan_byte_accessible+0x15/0x30 mm/kasan/generic.c:210
Code: 00 00 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f 40 d6 48 b8 00 00 00 00 00 fc ff df 48 c1 ef 03 48 01 c7 <0f> b6 07 3c 07 0f 96 c0 e9 8e 5f 68 09 66 66 2e 0f 1f 84 00 00 00
RSP: 0018:ffffc90007d076a0 EFLAGS: 00010082
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff8bee97ca RDI: dffffc0000000019
RBP: 00000000000000c8 R08: 0000000000000001 R09: 0000000000000000
R10: ffffffff926ad55f R11: 0000000000000000 R12: ffffffff8bee97ca
R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000000
FS: 00007f20dbb46880(0000) GS:ffff888095581000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005571aa07b64d CR3: 000000006d254000 CR4: 0000000000352ef0
----------------
Code disassembly (best guess):
0: 00 00 add %al,(%rax)
2: 0f 1f 00 nopl (%rax)
5: 90 nop
6: 90 nop
7: 90 nop
8: 90 nop
9: 90 nop
a: 90 nop
b: 90 nop
c: 90 nop
d: 90 nop
e: 90 nop
f: 90 nop
10: 90 nop
11: 90 nop
12: 90 nop
13: 90 nop
14: 90 nop
15: 0f 1f 40 d6 nopl -0x2a(%rax)
19: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax
20: fc ff df
23: 48 c1 ef 03 shr $0x3,%rdi
27: 48 01 c7 add %rax,%rdi
* 2a: 0f b6 07 movzbl (%rdi),%eax <-- trapping instruction
2d: 3c 07 cmp $0x7,%al
2f: 0f 96 c0 setbe %al
32: e9 8e 5f 68 09 jmp 0x9685fc5
37: 66 data16
38: 66 data16
39: 2e cs
3a: 0f .byte 0xf
3b: 1f (bad)
3c: 84 00 test %al,(%rax)
Tested on:
commit: 6628e7d4 Linux 7.4-rc1
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=157fe62d580000
kernel config: https://syzkaller.appspot.com/x/.config?x=f4b0888d27d9a541
dashboard link: https://syzkaller.appspot.com/bug?extid=54648a6c1187a7ef46a6
compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
userspace arch: i386
patch: https://syzkaller.appspot.com/x/patch.diff?x=15be75e1580000
next parent reply other threads:[~2026-11-02 11:25 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20261102103745.7043-1-kartikey406@gmail.com>
2026-11-02 11:25 ` syzbot [this message]
[not found] <20261102120252.9880-1-kartikey406@gmail.com>
2026-11-02 12:22 ` syzbot
[not found] <20261101203703.165-1-drifabdelmalekmohamedsaid@gmail.com>
2026-11-01 21:08 ` syzbot
2026-11-01 18:26 syzbot
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