syzbot


WARNING: refcount bug in dvb_device_open (3)

Status: upstream: reported on 2026/02/17 16:08
Subsystems: media
[Documentation on labels]
Reported-by: syzbot+2e428058cafb408fb695@syzkaller.appspotmail.com
First crash: 51d, last: 5h49m
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [media?] WARNING: refcount bug in dvb_device_open (3) 0 (1) 2026/02/17 16:08
Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 WARNING: refcount bug in dvb_device_open 13 1 55d 55d 0/3 upstream: reported on 2026/02/09 03:53
upstream WARNING: refcount bug in dvb_device_open (2) media 13 1 157d 153d 0/29 auto-obsoleted due to no activity on 2026/01/28 21:06
upstream WARNING: refcount bug in dvb_device_open media 13 1 358d 354d 0/29 auto-obsoleted due to no activity on 2025/07/21 00:17

Sample crash report:
------------[ cut here ]------------
refcount_t: saturated; leaking memory.
WARNING: lib/refcount.c:22 at refcount_warn_saturate+0x8c/0x110 lib/refcount.c:22, CPU#1: syz.3.1965/12725
Modules linked in:
CPU: 1 UID: 0 PID: 12725 Comm: syz.3.1965 Tainted: G             L      syzkaller #0 PREEMPT_{RT,(full)} 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
RIP: 0010:refcount_warn_saturate+0x8c/0x110 lib/refcount.c:22
Code: 75 68 e8 77 de 25 fd 48 8d 3d a0 00 d6 0a 67 48 0f b9 3a eb 66 85 db 74 3e 83 fb 01 75 4c e8 5b de 25 fd 48 8d 3d 94 00 d6 0a <67> 48 0f b9 3a eb 4a e8 48 de 25 fd 48 8d 3d 91 00 d6 0a 67 48 0f
RSP: 0018:ffffc900042076f8 EFLAGS: 00010287
RAX: ffffffff849ea815 RBX: 0000000000000001 RCX: 0000000000080000
RDX: ffffc9001ea02000 RSI: 0000000000000c87 RDI: ffffffff8f74a8b0
RBP: 00000000ffffffff R08: ffff888037338000 R09: 0000000000000005
R10: 0000000000000100 R11: 0000000000000004 R12: ffff88802c03ec18
R13: ffffffff995a2980 R14: ffff88802c03ec10 R15: ffff88802c03ec00
FS:  00007f1103ba66c0(0000) GS:ffff888126432000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f1105935980 CR3: 000000002a34c000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 __refcount_add include/linux/refcount.h:-1 [inline]
 __refcount_inc include/linux/refcount.h:366 [inline]
 refcount_inc include/linux/refcount.h:383 [inline]
 kref_get include/linux/kref.h:45 [inline]
 dvb_device_get drivers/media/dvb-core/dvbdev.c:621 [inline]
 dvb_device_open+0x31f/0x360 drivers/media/dvb-core/dvbdev.c:106
 chrdev_open+0x4d0/0x5f0 fs/char_dev.c:411
 do_dentry_open+0x83d/0x13e0 fs/open.c:949
 vfs_open+0x3b/0x350 fs/open.c:1081
 do_open fs/namei.c:4677 [inline]
 path_openat+0x2e43/0x38a0 fs/namei.c:4836
 do_file_open+0x23e/0x4a0 fs/namei.c:4865
 do_sys_openat2+0x113/0x200 fs/open.c:1366
 do_sys_open fs/open.c:1372 [inline]
 __do_sys_openat fs/open.c:1388 [inline]
 __se_sys_openat fs/open.c:1383 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1383
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f110590d04e
Code: 08 0f 85 a5 a8 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 <c3> 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 80 00 00 00 00 48 83 ec 08
RSP: 002b:00007f1103ba5b28 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f1103ba66c0 RCX: 00007f110590d04e
RDX: 0000000000000002 RSI: 00007f1103ba5c00 RDI: ffffffffffffff9c
RBP: 00007f1103ba5c00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: cccccccccccccccd
R13: 00007f1105bc6038 R14: 00007f1105bc5fa0 R15: 00007ffe3b1861e8
 </TASK>
----------------
Code disassembly (best guess):
   0:	75 68                	jne    0x6a
   2:	e8 77 de 25 fd       	call   0xfd25de7e
   7:	48 8d 3d a0 00 d6 0a 	lea    0xad600a0(%rip),%rdi        # 0xad600ae
   e:	67 48 0f b9 3a       	ud1    (%edx),%rdi
  13:	eb 66                	jmp    0x7b
  15:	85 db                	test   %ebx,%ebx
  17:	74 3e                	je     0x57
  19:	83 fb 01             	cmp    $0x1,%ebx
  1c:	75 4c                	jne    0x6a
  1e:	e8 5b de 25 fd       	call   0xfd25de7e
  23:	48 8d 3d 94 00 d6 0a 	lea    0xad60094(%rip),%rdi        # 0xad600be
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	eb 4a                	jmp    0x7b
  31:	e8 48 de 25 fd       	call   0xfd25de7e
  36:	48 8d 3d 91 00 d6 0a 	lea    0xad60091(%rip),%rdi        # 0xad600ce
  3d:	67                   	addr32
  3e:	48                   	rex.W
  3f:	0f                   	.byte 0xf

Crashes (7):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/04/05 15:36 upstream 3aae9383f42f 4440e7c2 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING: refcount bug in dvb_device_open
2026/03/24 10:50 upstream c369299895a5 baf8bf12 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING: refcount bug in dvb_device_open
2026/03/06 10:11 upstream 5ee8dbf54602 31e9c887 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING: refcount bug in dvb_device_open
2026/02/17 14:55 upstream c22e26bd0906 e439b951 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING: refcount bug in dvb_device_open
2026/02/13 15:20 upstream c22e26bd0906 6a673c50 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING: refcount bug in dvb_device_open
2026/03/29 22:39 linux-next 3b058d1aeeef 356bdfc9 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root WARNING: refcount bug in dvb_device_open
2026/02/23 05:16 linux-next d4906ae14a5f 6e7b5511 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce WARNING: refcount bug in dvb_device_open
* Struck through repros no longer work on HEAD.