KCSAN: data-race in data_alloc / data_push_tail (4)

Status: moderation: reported C repro on 2026/10/02 03:22
Subsystems: audit
Labels: race:benign prio:high
[Documentation on labels]
Reported-by: syzbot+8324b8fd984b86905a66@syzkaller.appspotmail.com
First crash: 2d20h, last: 1d22h
▶ ▼ ✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision
e3e16dfc assessment-security DenialOfService: ❌ Exploitable: ❌ FilesystemTrigger: ✅ NetworkTrigger: ✅ PeripheralTrigger: ✅ RemoteTrigger: ✅ Unprivileged: ✅ UserNamespace: ✅ VMGuestTrigger: ✅ VMHostTrigger: ✅ ❓ KCSAN: data-race in data_alloc / data_push_tail (4) 2026/10/04 00:02 2026/10/04 00:02 2026/10/04 00:05 57bbd979
fbcc89ea assessment-kcsan Benign: ✅ ❓ KCSAN: data-race in data_alloc / data_push_tail (4) 2026/10/02 03:22 2026/10/02 03:22 2026/10/02 03:59 6d32eb1f
▶ ▼ Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in data_alloc / data_push_tail (3) prio:low ext4 block 6 75 72d 756d 0/29 auto-obsoleted due to no activity on 2026/09/18 22:44
upstream KCSAN: data-race in data_alloc / data_push_tail (2) batman 6 44 802d 946d 0/29 auto-obsoleted due to no activity on 2024/08/28 06:32
upstream KCSAN: data-race in data_alloc / data_push_tail ext4 6 94 1257d 1720d 0/29 auto-obsoleted due to no activity on 2023/05/31 17:30

Sample crash report:
==================================================================
BUG: KCSAN: data-race in data_alloc / data_push_tail

write to 0xffffffff895c6090 of 8 bytes by task 3647 on cpu 0:
 data_alloc+0x240/0x380 kernel/printk/printk_ringbuffer.c:1116
 prb_reserve+0x8e3/0xaf0 kernel/printk/printk_ringbuffer.c:1727
 vprintk_store+0x54e/0x910 kernel/printk/printk.c:2354
 vprintk_emit+0x1a4/0x610 kernel/printk/printk.c:2455
 devkmsg_emit+0x7f/0xb0 kernel/printk/printk.c:733
 devkmsg_write+0x1e2/0x2b0 kernel/printk/printk.c:796
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x57f/0x9a0 fs/read_write.c:687
 ksys_write+0xdc/0x1a0 fs/read_write.c:739

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/03 01:32 git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 5e0f8396d480 38f7f0d1 .config console log report C ci2-upstream-kcsan-gce KCSAN: data-race in data_alloc / data_push_tail
2026/10/02 03:22 upstream ce1e0223d8ad 6d32eb1f .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in data_alloc / data_push_tail
* Struck through repros no longer work on HEAD.