WARNING in kcov_task_exit

Status: upstream: reported on 2025/10/05 04:48
Subsystems: kernel
Labels: prio:low
[Documentation on labels]
Reported-by: syzbot+47cf95ca1f9dcca872c8@syzkaller.appspotmail.com
Fix commit: kcov: fix data corruption and race conditions on PREEMPT_RT by moving saved remote state to task_struct
Patched on: [ci-upstream-rust-kasan-gce], missing on: [ci-qemu-gce-upstream-auto ci-qemu-native-arm64-kvm ci-qemu-upstream ci-qemu-upstream-386 ci-qemu2-arm32 ci-qemu2-arm64 ci-qemu2-arm64-compat ci-qemu2-arm64-mte ci-qemu2-riscv64 ci-snapshot-upstream-root ci-upstream-bpf-kasan-gce ci-upstream-bpf-next-kasan-gce ci-upstream-gce-arm64 ci-upstream-gce-leak ci-upstream-kasan-badwrites-root ci-upstream-kasan-gce ci-upstream-kasan-gce-386 ci-upstream-kasan-gce-root ci-upstream-kasan-gce-selinux-root ci-upstream-kasan-gce-smack-root ci-upstream-kmsan-gce-386-root ci-upstream-kmsan-gce-root ci-upstream-linux-next-kasan-gce-root ci-upstream-net-kasan-gce ci-upstream-net-this-kasan-gce ci2-upstream-fs ci2-upstream-kcsan-gce ci2-upstream-usb]
First crash: 311d, last: 6m
✨ AI Jobs (3)
ID Workflow Result Correct Bug Created Started Finished Revision
46754938 assessment-security DenialOfService: ❌ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ WARNING in kcov_task_exit 2026/06/01 07:00 2026/06/01 07:00 2026/06/01 08:09 6b4a8443
36d40745 assessment-security 💥 WARNING in kcov_task_exit 2026/05/15 10:34 2026/05/15 10:34 2026/05/15 10:35 9cd3beaa
523e8a01 repro WARNING in kcov_task_exit 2026/03/07 12:39 2026/03/07 12:39 2026/03/07 12:49 31e9c887
Discussions (4)
Title Replies (including bot) Last reply
[PATCH v6] kcov: fix data corruption and race conditions on PREEMPT_RT by moving saved remote state to task_struct 5 (5) 2026/07/16 09:12
Re: [PATCH v5] kcov: fix data corruption and race conditions on PREEMPT_RT by moving saved remote state to task_struct 2 (2) 2026/07/10 10:43
[PATCH] kcov: fix potential kcov_mode corruption under CONFIG_PREEMPT_RT 5 (5) 2026/05/21 08:38
[syzbot] [kernel?] WARNING in kcov_task_exit 0 (1) 2025/10/05 04:48

Sample crash report:
------------[ cut here ]------------
kcov->t != t
WARNING: kernel/kcov.c:475 at kcov_task_exit+0x181/0x240 kernel/kcov.c:475, CPU#0: syz.5.7279/28148
Modules linked in:
CPU: 0 UID: 0 PID: 28148 Comm: syz.5.7279 Tainted: G             L      syzkaller #0 PREEMPT_{RT,(full)} 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:kcov_task_exit+0x181/0x240 kernel/kcov.c:475
Code: 90 00 00 00 e8 c0 d5 57 00 4c 89 f7 5b 41 5e 41 5f e9 a3 95 5d 00 7c 40 5b 41 5e 41 5f c3 cc cc cc cc cc 90 0f 0b 90 eb 10 90 <0f> 0b 90 eb 0a 90 0f 0b 90 eb 04 90 0f 0b 90 4c 89 ff 5b 41 5e 41
RSP: 0018:ffffc90006277ae0 EFLAGS: 00010206
RAX: a02b72acc4d88d00 RBX: ffff88803d5fdd00 RCX: 0000000000000000
RDX: 0000000031b9c3b6 RSI: ffffffff8bca5960 RDI: 00000000ffffffff
RBP: ffffc90006277c30 R08: ffffffff8b45db80 R09: 0000000000000000
R10: 0000000000000000 R11: ffffffff8e1c3000 R12: 0000000000000000
R13: 0000000000000004 R14: ffff88805d782800 R15: ffff88805d782808
FS:  00007f36acd666c0(0000) GS:ffff888125c46000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f9415b3dff8 CR3: 000000004240a000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 do_exit+0x159/0x2360 kernel/exit.c:942
 do_group_exit+0x22d/0x2f0 kernel/exit.c:1152
 get_signal+0x121b/0x12c0 kernel/signal.c:3046
 arch_do_signal_or_restart+0xbb/0x860 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:66 [inline]
 exit_to_user_mode_loop+0x104/0x730 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:318 [inline]
 do_syscall_64+0x353/0x580 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f36aeb0e0d9
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:00007f36acd660e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007f36aed95fa8 RCX: 00007f36aeb0e0d9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f36aed95fa8
RBP: 00007f36aed95fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f36aed96038 R14: 00007ffd8704b0e0 R15: 00007ffd8704b1c8
 </TASK>

Crashes (22098):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/08 18:07 upstream a59f57e2aa12 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/08 16:51 upstream a59f57e2aa12 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/08 15:29 upstream a59f57e2aa12 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/08 14:23 upstream a59f57e2aa12 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/08 13:19 upstream a59f57e2aa12 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/08 10:17 upstream 9a143525f62b e4ef95d6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/08 09:45 upstream 9a143525f62b e4ef95d6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/08 08:32 upstream 9a143525f62b e4ef95d6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/08 07:01 upstream 9a143525f62b e4ef95d6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/08 05:13 upstream 9a143525f62b e4ef95d6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/08 04:02 upstream 9a143525f62b e4ef95d6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/08 02:48 upstream 9a143525f62b e4ef95d6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/08 02:41 upstream 9a143525f62b e4ef95d6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/08 01:09 upstream f9a2394a2348 e4ef95d6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/07 23:23 upstream f9a2394a2348 e4ef95d6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/07 21:20 upstream f9a2394a2348 e4ef95d6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/07 19:09 upstream f9a2394a2348 e4ef95d6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/07 17:29 upstream f9a2394a2348 e4ef95d6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/07 17:16 upstream f9a2394a2348 e4ef95d6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/07 15:47 upstream f9a2394a2348 e4ef95d6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/07 14:27 upstream f9a2394a2348 e4ef95d6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/07 13:21 upstream f9a2394a2348 e4ef95d6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/07 12:15 upstream f9a2394a2348 e4ef95d6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/07 11:02 upstream f9a2394a2348 e4ef95d6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/07 09:44 upstream f9a2394a2348 c38879ea .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/07 08:44 upstream f9a2394a2348 c38879ea .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/07 08:00 upstream f9a2394a2348 c38879ea .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/07 07:00 upstream 0d8395707651 c38879ea .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/07 05:41 upstream 0d8395707651 c38879ea .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/07 04:31 upstream 0d8395707651 c38879ea .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/07 03:29 upstream 0d8395707651 c38879ea .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/07 01:47 upstream 0d8395707651 c38879ea .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/07 01:17 upstream 0d8395707651 c38879ea .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/06 22:33 upstream 0d8395707651 c38879ea .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/06 21:11 upstream 0d8395707651 c38879ea .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/06 18:44 upstream 0d8395707651 c38879ea .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/06 17:23 upstream 0d8395707651 c38879ea .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/06 16:04 upstream 0d8395707651 c38879ea .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/06 15:52 upstream 0d8395707651 c38879ea .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/06 12:55 upstream 0d8395707651 cd5b1963 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/06 11:42 upstream 0d8395707651 cd5b1963 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/06 10:41 upstream 0d8395707651 cd5b1963 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/06 09:23 upstream 0d8395707651 cd5b1963 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/06 08:27 upstream 0d8395707651 cd5b1963 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/06 07:00 upstream 0d8395707651 cd5b1963 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/06 04:47 upstream 0d8395707651 cd5b1963 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/06 03:35 upstream 0d8395707651 cd5b1963 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/06/01 04:51 upstream 8d9c51eac648 6b4a8443 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/05/15 09:47 upstream 70eda68668d1 9cd3beaa .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/03/07 12:25 upstream 651690480a96 5cb44a80 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2025/10/04 19:59 upstream cbf33b8e0b36 49379ee0 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2025/10/01 04:45 upstream 50c19e20ed2e 65a0eece .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/07/08 14:15 linux-next 5c73cd9f0819 ab40da58 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root WARNING in kcov_task_exit
2026/07/08 13:15 linux-next 5c73cd9f0819 ab40da58 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce WARNING in kcov_task_exit
* Struck through repros no longer work on HEAD.