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divide error in fbcon_switch

Status: upstream: reported C repro on 2019/12/03 01:21
Reported-by: syzbot+383ba193d61507226c6f@syzkaller.appspotmail.com
First crash: 1599d, last: 603d
Fix bisection: failed (error log, bisect log)
  
▶ ▼ Similar bugs (2)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream divide error in fbcon_switch fbdev C inconclusive done 326 1393d 1598d 0/26 closed as dup on 2020/07/27 22:47
linux-4.19 divide error in fbcon_switch C done 259 1360d 1599d 1/1 fixed on 2020/09/01 18:34
▶ ▼ Last patch testing requests (2)
Created Duration User Patch Repo Result
2023/03/04 09:32 0m retest repro linux-4.14.y error OK
2022/12/03 16:30 12m retest repro linux-4.14.y report log
▶ ▼ Fix bisection attempts (25)
Created Duration User Patch Repo Result
2022/10/13 02:08 0m bisect fix linux-4.14.y error job log (0)
2022/08/25 04:18 27m bisect fix linux-4.14.y job log (0) log
2022/07/26 03:50 27m bisect fix linux-4.14.y job log (0) log
2022/06/26 03:28 22m bisect fix linux-4.14.y job log (0) log
2022/05/27 03:06 22m bisect fix linux-4.14.y job log (0) log
2022/04/26 22:07 23m bisect fix linux-4.14.y job log (0) log
2022/03/27 13:24 24m bisect fix linux-4.14.y job log (0) log
2022/02/25 12:59 24m bisect fix linux-4.14.y job log (0) log
2022/01/26 12:32 27m bisect fix linux-4.14.y job log (0) log
2021/12/27 12:05 26m bisect fix linux-4.14.y job log (0) log
2021/11/27 11:40 25m bisect fix linux-4.14.y job log (0) log
2021/10/28 10:40 27m bisect fix linux-4.14.y job log (0) log
2021/09/23 08:23 27m bisect fix linux-4.14.y job log (0) log
2021/08/24 07:38 26m bisect fix linux-4.14.y job log (0) log
2021/07/25 03:02 25m bisect fix linux-4.14.y job log (0) log
2021/06/25 02:38 22m bisect fix linux-4.14.y job log (0) log
2021/05/26 02:00 26m bisect fix linux-4.14.y job log (0) log
2021/04/26 01:18 30m bisect fix linux-4.14.y job log (0) log
2021/03/27 00:19 21m bisect fix linux-4.14.y job log (0) log
2021/02/24 23:18 23m bisect fix linux-4.14.y job log (0) log
2021/01/25 22:34 22m bisect fix linux-4.14.y job log (0) log
2020/12/26 19:06 24m bisect fix linux-4.14.y job log (0) log
2020/11/26 18:39 26m bisect fix linux-4.14.y job log (0) log
2020/10/27 17:34 22m bisect fix linux-4.14.y job log (0) log
2020/09/27 17:10 23m bisect fix linux-4.14.y job log (0) log

Sample crash report:
audit: type=1400 audit(1595480216.708:8): avc:  denied  { execmem } for  pid=6345 comm="syz-executor795" scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:system_r:kernel_t:s0 tclass=process permissive=1
divide error: 0000 [#1] PREEMPT SMP KASAN
Modules linked in:
CPU: 0 PID: 25 Comm: kworker/0:1 Not tainted 4.14.189-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events console_callback
task: ffff8880a9a3c680 task.stack: ffff8880a9a30000
RIP: 0010:fbcon_update_softback drivers/video/fbdev/core/fbcon.c:354 [inline]
RIP: 0010:fbcon_switch+0x1cd/0x1b1f drivers/video/fbdev/core/fbcon.c:2195
RSP: 0018:ffff8880a9a37a48 EFLAGS: 00010246
RAX: 0000000000008000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffff8880a9a3cf58 RDI: ffff88809758d43c
RBP: ffff8882192b0040 R08: ffffffff8a100a1c R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff88809758d100
R13: ffff8880a5b19500 R14: 0000000000000001 R15: ffff88809758d578
FS:  0000000000000000(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa0387706c0 CR3: 00000000a848e000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 redraw_screen+0x32c/0x790 drivers/tty/vt/vt.c:689
 complete_change_console+0xf9/0x5b0 drivers/tty/vt/vt_ioctl.c:1284
 change_console+0x15c/0x500 drivers/tty/vt/vt_ioctl.c:1409
 console_callback+0x32c/0x380 drivers/tty/vt/vt.c:2473
 process_one_work+0x793/0x14a0 kernel/workqueue.c:2116
 worker_thread+0x5cc/0xff0 kernel/workqueue.c:2250
 kthread+0x30d/0x420 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
Code: 4a 0b d6 07 83 c2 03 48 89 2d 80 0b d6 07 48 89 2d f9 0a d6 07 38 ca 7c 08 84 c9 0f 85 80 17 00 00 41 8b 9c 24 3c 03 00 00 31 d2 <f7> f3 83 f8 05 89 44 24 10 0f 8e 1c 0c 00 00 e8 3f 48 39 fe 8b 
RIP: fbcon_update_softback drivers/video/fbdev/core/fbcon.c:354 [inline] RSP: ffff8880a9a37a48
RIP: fbcon_switch+0x1cd/0x1b1f drivers/video/fbdev/core/fbcon.c:2195 RSP: ffff8880a9a37a48
---[ end trace 72b3c86f77fc6192 ]---

Crashes (282):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2020/07/23 04:58 linux-4.14.y 69b94dd6dcd1 340ea530 .config console log report syz C ci2-linux-4-14
2019/12/03 00:21 linux-4.14.y fbc5fe7a54d0 ab342da3 .config console log report syz C ci2-linux-4-14
2020/07/29 05:42 linux-4.14.y 69b94dd6dcd1 cb93dc6a .config console log report ci2-linux-4-14
2020/07/28 18:32 linux-4.14.y 69b94dd6dcd1 cb93dc6a .config console log report ci2-linux-4-14
2020/07/28 11:09 linux-4.14.y 69b94dd6dcd1 cb93dc6a .config console log report ci2-linux-4-14
2020/07/26 07:26 linux-4.14.y 69b94dd6dcd1 1f7cc1ca .config console log report ci2-linux-4-14
2020/07/21 02:28 linux-4.14.y b850307b279c d88894e6 .config console log report ci2-linux-4-14
2020/07/20 08:46 linux-4.14.y b850307b279c 9c812472 .config console log report ci2-linux-4-14
2020/07/19 20:57 linux-4.14.y b850307b279c 9c812472 .config console log report ci2-linux-4-14
2020/07/19 17:58 linux-4.14.y b850307b279c 9c812472 .config console log report ci2-linux-4-14
2020/07/19 10:47 linux-4.14.y b850307b279c 9c812472 .config console log report ci2-linux-4-14
2020/07/19 09:22 linux-4.14.y b850307b279c 9c812472 .config console log report ci2-linux-4-14
2020/07/19 03:19 linux-4.14.y b850307b279c 9c812472 .config console log report ci2-linux-4-14
2020/07/16 12:09 linux-4.14.y b850307b279c b090c643 .config console log report ci2-linux-4-14
2020/07/16 10:14 linux-4.14.y b850307b279c ada108d0 .config console log report ci2-linux-4-14
2020/07/15 11:20 linux-4.14.y b850307b279c ada108d0 .config console log report ci2-linux-4-14
2020/07/13 20:57 linux-4.14.y b850307b279c ce4c95b3 .config console log report ci2-linux-4-14
2020/07/13 17:04 linux-4.14.y b850307b279c f90ec899 .config console log report ci2-linux-4-14
2020/07/12 08:16 linux-4.14.y b850307b279c 115e1930 .config console log report ci2-linux-4-14
2020/07/11 14:10 linux-4.14.y b850307b279c 7ba05d2d .config console log report ci2-linux-4-14
2020/07/10 17:37 linux-4.14.y b850307b279c 56d01184 .config console log report ci2-linux-4-14
2020/07/09 04:08 linux-4.14.y b850307b279c 9f9845eb .config console log report ci2-linux-4-14
2020/07/08 23:08 linux-4.14.y b850307b279c 9f9845eb .config console log report ci2-linux-4-14
2020/07/05 20:01 linux-4.14.y b850307b279c 22f87567 .config console log report ci2-linux-4-14
2020/07/05 17:47 linux-4.14.y b850307b279c 22f87567 .config console log report ci2-linux-4-14
2020/07/05 01:43 linux-4.14.y b850307b279c 24d7f505 .config console log report ci2-linux-4-14
2020/07/02 13:18 linux-4.14.y b850307b279c f30c14bf .config console log report ci2-linux-4-14
2020/07/02 03:50 linux-4.14.y b850307b279c bed10395 .config console log report ci2-linux-4-14
2020/07/01 23:52 linux-4.14.y b850307b279c bed10395 .config console log report ci2-linux-4-14
2020/07/01 15:03 linux-4.14.y b850307b279c 39acb39d .config console log report ci2-linux-4-14
2020/07/01 11:10 linux-4.14.y b850307b279c 090d8f7b .config console log report ci2-linux-4-14
2020/06/29 01:22 linux-4.14.y b850307b279c a2cdad9d .config console log report ci2-linux-4-14
2020/06/28 22:59 linux-4.14.y b850307b279c a2cdad9d .config console log report ci2-linux-4-14
2020/06/26 08:59 linux-4.14.y b850307b279c aea82c00 .config console log report ci2-linux-4-14
2020/06/22 19:10 linux-4.14.y b850307b279c 1afe1535 .config console log report ci2-linux-4-14
2020/06/22 02:07 linux-4.14.y b850307b279c 4f2acff9 .config console log report ci2-linux-4-14
2020/06/21 07:21 linux-4.14.y b850307b279c c655ec77 .config console log report ci2-linux-4-14
2020/06/21 01:02 linux-4.14.y b850307b279c c655ec77 .config console log report ci2-linux-4-14
2020/06/20 14:03 linux-4.14.y b850307b279c c655ec77 .config console log report ci2-linux-4-14
2020/06/20 03:35 linux-4.14.y b850307b279c c655ec77 .config console log report ci2-linux-4-14
2020/06/18 14:04 linux-4.14.y b850307b279c 3ea11d3f .config console log report ci2-linux-4-14
2020/06/18 06:42 linux-4.14.y b850307b279c d45a4d69 .config console log report ci2-linux-4-14
2020/06/18 00:25 linux-4.14.y b850307b279c d45a4d69 .config console log report ci2-linux-4-14
2020/06/17 14:27 linux-4.14.y b850307b279c b6c46f43 .config console log report ci2-linux-4-14
* Struck through repros no longer work on HEAD.