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-linux-next-kasan-gce-root 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-net-kasan-gce ci-upstream-net-this-kasan-gce ci2-upstream-fs ci2-upstream-kcsan-gce ci2-upstream-usb]
First crash: 304d, last: 23m
✨ AI Jobs (3)
ID Workflow Result Correct Bug Created Started Finished Revision Error
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
failed to run ["git" "-c" "core.hooksPath=/dev/null" "checkout" "70eda68668d1476b459b64e69b8f36659fa9dfa8"]: exit status 128
fatal: sha1 file '/app/workdir/repo/linux/.git/index.lock' write error. Out...
truncated to first 200 bytes; open job for full error
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#1: syz.8.4455/22887
Modules linked in:
CPU: 1 UID: 0 PID: 22887 Comm: syz.8.4455 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 e0 d2 57 00 4c 89 f7 5b 41 5e 41 5f e9 c3 92 5d 00 7c 40 5b 41 5e 41 5f e9 97 5b 82 09 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:ffffc9000860fd20 EFLAGS: 00010287
RAX: 257b24a8e34f2400 RBX: ffff888032f1dd00 RCX: 0000000000000000
RDX: 00000000b8e13370 RSI: ffffffff8bca7860 RDI: 00000000ffffffff
RBP: ffffc9000860fe80 R08: ffffffff8b46cb20 R09: 0000000000000000
R10: 0000000000000000 R11: ffffffff8e1c3000 R12: 0000000000000000
R13: ffff888032f1dd00 R14: ffff888053ee6400 R15: ffff888053ee6408
FS:  000055558b6d9500(0000) GS:ffff888125d3e000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000555593f2e4e8 CR3: 00000000783dc000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 do_exit+0x159/0x2360 kernel/exit.c:942
 do_group_exit+0x22d/0x2f0 kernel/exit.c:1152
 __do_sys_exit_group kernel/exit.c:1163 [inline]
 __se_sys_exit_group kernel/exit.c:1161 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1161
 x64_sys_call+0x221a/0x2240 arch/x86/include/generated/asm/syscalls_64.h:232
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd2eeb3e019
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:00007ffc3f877a48 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fd2eeb3e019
RDX: 00007fd2edd99000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007ffc3f877aac R08: 0000000000000000 R09: 00000000000927c0
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000175
R13: 00000000000927c0 R14: 000000000012eb65 R15: 00007ffc3f877b00
 </TASK>

Crashes (21663):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/01 18:20 upstream 0131b508c0e2 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/01 17:52 upstream 0131b508c0e2 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/01 16:50 upstream 0131b508c0e2 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/01 14:59 upstream 0131b508c0e2 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/01 13:48 upstream 0131b508c0e2 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/01 11:50 upstream 0131b508c0e2 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/01 09:15 upstream 0131b508c0e2 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/01 08:03 upstream 0131b508c0e2 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/01 07:12 upstream 0131b508c0e2 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/01 06:12 upstream 0131b508c0e2 7664cf44 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/01 04:32 upstream 8ba098e6b6ff 7664cf44 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/01 02:35 upstream 8ba098e6b6ff 7664cf44 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/01 01:48 upstream 8ba098e6b6ff 7664cf44 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/08/01 00:37 upstream 8ba098e6b6ff 7664cf44 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/07/31 23:36 upstream 8ba098e6b6ff 7664cf44 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/07/31 22:16 upstream 8ba098e6b6ff 7664cf44 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/07/31 21:20 upstream 8ba098e6b6ff 7664cf44 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/07/31 19:59 upstream 8ba098e6b6ff 7664cf44 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/07/31 18:56 upstream 8ba098e6b6ff 7664cf44 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/07/31 16:16 upstream 8ba098e6b6ff 7664cf44 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/07/31 16:11 upstream 8ba098e6b6ff 7664cf44 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/07/31 14:59 upstream 8ba098e6b6ff 7664cf44 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/07/31 13:32 upstream 8ba098e6b6ff aaffb173 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/07/31 11:38 upstream 8ba098e6b6ff aaffb173 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/07/31 10:32 upstream 3708dd948844 aaffb173 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/07/31 09:32 upstream 3708dd948844 aaffb173 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/07/31 07:34 upstream 3708dd948844 aaffb173 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/07/31 06:16 upstream 3708dd948844 aaffb173 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/07/31 04:28 upstream 3708dd948844 aaffb173 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/07/31 03:46 upstream 3708dd948844 aaffb173 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/07/31 02:40 upstream 3708dd948844 aaffb173 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/07/31 00:02 upstream 3708dd948844 aaffb173 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/07/30 22:44 upstream 3708dd948844 aaffb173 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/07/30 20:11 upstream 11028ab62899 aaffb173 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/07/30 18:21 upstream 11028ab62899 aaffb173 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/07/30 16:23 upstream 11028ab62899 2377cd3d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/07/30 12:19 upstream 11028ab62899 2377cd3d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/07/30 10:46 upstream 11028ab62899 2377cd3d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/07/30 09:31 upstream 11028ab62899 2377cd3d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/07/30 07:12 upstream 11028ab62899 2377cd3d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/07/30 05:54 upstream 11028ab62899 2377cd3d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in kcov_task_exit
2026/07/30 04:25 upstream 11028ab62899 cb1587ea .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.