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From: syzbot <syzbot+225231fce6755d40d078@syzkaller.appspotmail.com>
To: linux-kernel@vger.kernel.org, linux-sound@vger.kernel.org,
	perex@perex.cz,  syzkaller-bugs@googlegroups.com, tiwai@suse.com
Subject: Re: [syzbot] [sound?] WARNING: ODEBUG bug in dummy_pcm_close
Date: Wed, 26 Aug 2026 23:03:32 -0700	[thread overview]
Message-ID: <6a8fd334.27659fcc.2ceef7.000e.GAE@google.com> (raw)
In-Reply-To: <6a8f0de8.1d9ded08.62e62.00b5.GAE@google.com>

syzbot has found a reproducer for the following issue on:

HEAD commit:    818bebeb63dd drm/xe: Don't hand out the flat CCS storage a..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13f58579580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=ccca94d2c01b9e78
dashboard link: https://syzkaller.appspot.com/bug?extid=225231fce6755d40d078
compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12315625580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=17a84579580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-818bebeb.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/6e4100526b12/vmlinux-818bebeb.xz
kernel image: https://storage.googleapis.com/syzbot-assets/723c4783ee96/bzImage-818bebeb.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+225231fce6755d40d078@syzkaller.appspotmail.com

------------[ cut here ]------------
ODEBUG: free active (active state 0) object: ffff888034a07520 object type: hrtimer hint: dummy_hrtimer_callback+0x0/0x160 sound/drivers/dummy.c:325
WARNING: lib/debugobjects.c:629 at debug_print_object+0x198/0x2b0 lib/debugobjects.c:629, CPU#3: syz.0.149/6362
Modules linked in:
CPU: 3 UID: 0 PID: 6362 Comm: syz.0.149 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:debug_print_object+0x1a5/0x2b0 lib/debugobjects.c:629
Code: b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 75 4f 48 8d 3d d8 e1 1f 0c 41 56 48 8b 14 ed 40 71 61 8c 4c 89 e6 <67> 48 0f b9 3a 58 83 05 22 4e 15 0c 01 48 83 c4 18 5b 5d 41 5c 41
RSP: 0018:ffffc9000520fb48 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: ffffc9000520fc30 RCX: 0000000000000000
RDX: ffffffff8c617080 RSI: ffffffff8c616c20 RDI: ffffffff914e1e30
RBP: 0000000000000003 R08: ffff888034a07520 R09: ffffffff8bf30280
R10: 0000000000000001 R11: 0000000000000000 R12: ffffffff8c616c20
R13: ffffffff8bf302c0 R14: ffffffff8962d870 R15: ffffc9000520fc48
FS:  0000555580a4f500(0000) GS:ffff8880d5ea2000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7df3feb7c0 CR3: 00000000556d2000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 __debug_check_no_obj_freed lib/debugobjects.c:1171 [inline]
 debug_check_no_obj_freed+0x4da/0x630 lib/debugobjects.c:1201
 slab_free_hook mm/slub.c:2609 [inline]
 slab_free mm/slub.c:6372 [inline]
 kfree+0x3d6/0x6c0 mm/slub.c:6687
 dummy_pcm_close+0x9a/0xd0 sound/drivers/dummy.c:609
 snd_pcm_release_substream.part.0+0x114/0x340 sound/core/pcm_native.c:2793
 snd_pcm_release_substream sound/core/pcm_native.c:2786 [inline]
 snd_pcm_release+0x10f/0x230 sound/core/pcm_native.c:2983
 __fput+0x3ff/0xb50 fs/file_table.c:512
 task_work_run+0x150/0x240 kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 __exit_to_user_mode_loop kernel/entry/common.c:70 [inline]
 exit_to_user_mode_loop+0x1d8/0x700 kernel/entry/common.c:101
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:336 [inline]
 do_syscall_64+0x661/0x790 arch/x86/entry/syscall_64.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7df3f9e0d9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffdeaf84e28 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007f7df4227da0 RCX: 00007f7df3f9e0d9
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007f7df4227da0 R08: 00007f7df4226038 R09: 0000000000000000
R10: 000000000003fda4 R11: 0000000000000246 R12: 0000000000010a73
R13: 00007f7df422609c R14: 0000000000010769 R15: 00007f7df4226090
 </TASK>
----------------
Code disassembly (best guess):
   0:	b8 00 00 00 00       	mov    $0x0,%eax
   5:	00 fc                	add    %bh,%ah
   7:	ff                   	lcall  (bad)
   8:	df 48 89             	fisttps -0x77(%rax)
   b:	fa                   	cli
   c:	48 c1 ea 03          	shr    $0x3,%rdx
  10:	80 3c 02 00          	cmpb   $0x0,(%rdx,%rax,1)
  14:	75 4f                	jne    0x65
  16:	48 8d 3d d8 e1 1f 0c 	lea    0xc1fe1d8(%rip),%rdi        # 0xc1fe1f5
  1d:	41 56                	push   %r14
  1f:	48 8b 14 ed 40 71 61 	mov    -0x739e8ec0(,%rbp,8),%rdx
  26:	8c
  27:	4c 89 e6             	mov    %r12,%rsi
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	58                   	pop    %rax
  30:	83 05 22 4e 15 0c 01 	addl   $0x1,0xc154e22(%rip)        # 0xc154e59
  37:	48 83 c4 18          	add    $0x18,%rsp
  3b:	5b                   	pop    %rbx
  3c:	5d                   	pop    %rbp
  3d:	41 5c                	pop    %r12
  3f:	41                   	rex.B


---
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.

      reply	other threads:[~2026-08-27  6:03 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-08-26 16:01 syzbot
2026-08-27  6:03 ` syzbot [this message]

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