syzbot

 sign-in | mailing list | source | docs | 🏰
🐞 Open [1340]
≡ Subsystems
🐞 Fixed [7118]
🐞 Invalid [18803]
⬇ Missing Backports [220]
≡ Crashes
Kernel Health Bugs/Month Bug Lifetimes Fuzzing
Total Repo Heatmap Subsystems Heatmap
✨ AI
💬 Send us feedback

KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read

Status: moderation: reported on 2023/12/09 00:01
Subsystems: mm
Labels: race:benign prio:high
[Documentation on labels]
Reported-by: syzbot+706dde8a3e5ef992fcad@syzkaller.appspotmail.com
First crash: 1050d, last: 2h18m
▶ ▼ ✨ AI Jobs (3)
ID Workflow Result Correct Bug Created Started Finished Revision Error
b0384c36-8501-4524-a9d1-a0253d5f5415 assessment-security DenialOfService: ❌ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ✅ UserNamespace: ✅ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read 2026/05/21 02:41 2026/05/21 02:41 2026/05/21 03:22 cf874a1cf36318c06202027159ddac14acf00db7
6bd39b22-15c8-4e79-b1a3-ff9c2ad13335 repro 💥 KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read 2026/03/10 12:22 2026/03/10 12:22 2026/03/10 12:22 5c03941b7fba0fd3b0326afc981322c89fe9ba52+ unexpected git log output: "warning: unable to access '/root/.config/git/attributes': Permission denied\nwarning: unable to access '/root/.config/git/attributes': Permission denied\n1f318b96cc84d7c2ab792fcc0bfd42a7ca890681\nLinux 7.0-rc3\ntorvalds@linux-foundation.org\nLinus Torvalds\nSun Mar 8 16:56:54 2026 -0700\nfc9f248d8c591454e257edd54ac4085d84f11e6a\nSun Mar 8 16:56:54 2026 -0700\n"
71db9653-a631-44dd-b50f-639baab5d8f4 assessment-kcsan Benign: ✅ Confident: ✅ ✅ KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read 2026/01/14 13:13 2026/01/14 13:13 2026/01/14 13:16 a9d6a79219801d2130df3b1a792c57f0e5428e9f

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

write to 0xffff8881055082e0 of 8 bytes by task 28815 on cpu 1:
 shmem_file_splice_read+0x40e/0x5a0 mm/shmem.c:3627
 do_splice_read fs/splice.c:980 [inline]
 splice_direct_to_actor+0x26e/0x670 fs/splice.c:1084
 do_splice_direct_actor fs/splice.c:1202 [inline]
 do_splice_direct+0x119/0x1a0 fs/splice.c:1228
 do_sendfile+0x382/0x650 fs/read_write.c:1372
 __do_sys_sendfile64 fs/read_write.c:1433 [inline]
 __se_sys_sendfile64 fs/read_write.c:1419 [inline]
 __x64_sys_sendfile64+0x105/0x150 fs/read_write.c:1419
 x64_sys_call+0x2dc4/0x3020 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

write to 0xffff8881055082e0 of 8 bytes by task 28816 on cpu 0:
 shmem_file_splice_read+0x40e/0x5a0 mm/shmem.c:3627
 do_splice_read fs/splice.c:980 [inline]
 splice_direct_to_actor+0x26e/0x670 fs/splice.c:1084
 do_splice_direct_actor fs/splice.c:1202 [inline]
 do_splice_direct+0x119/0x1a0 fs/splice.c:1228
 do_sendfile+0x382/0x650 fs/read_write.c:1372
 __do_sys_sendfile64 fs/read_write.c:1433 [inline]
 __se_sys_sendfile64 fs/read_write.c:1419 [inline]
 __x64_sys_sendfile64+0x105/0x150 fs/read_write.c:1419
 x64_sys_call+0x2dc4/0x3020 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000004a9b -> 0x0000000000004aa1

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 28816 Comm: syz.9.7564 Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
==================================================================

Crashes (2694):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/26 21:29 upstream d60ec36cab33 2b01f00e .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/05/26 17:37 upstream d60ec36cab33 a3e47276 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/05/26 08:58 upstream e8c2f9fdadee a3e47276 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/05/26 00:36 upstream e8c2f9fdadee c69befb3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/05/25 10:56 upstream e7ae89a0c97c c69befb3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/05/24 21:38 upstream 6a97c4d5262d c69befb3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/05/24 07:18 upstream 4cbfe4502e3d c69befb3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/05/23 17:39 upstream eed108edc117 c69befb3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/05/23 02:57 upstream 79bd2dded182 c69befb3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/05/22 15:38 upstream 45255ea1ca09 5f091fcc .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/05/22 13:31 upstream 6779b50faa56 5f091fcc .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/05/22 02:43 upstream 6779b50faa56 70ae9b03 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/05/21 17:54 upstream 758c807bb943 e195359d .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/05/21 13:36 upstream 8bc67e4db64a e195359d .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/05/21 02:54 upstream 8bc67e4db64a 41b8c833 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/05/20 18:08 upstream df685633c3db 62fb93a2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/05/20 11:51 upstream 27fa82620cba 62fb93a2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/05/20 02:08 upstream 27fa82620cba 0909d65f .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/05/19 22:23 upstream ab5fce87a778 223544dc .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/05/18 23:29 upstream 4d3a2a466b8d 9f74d399 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/05/18 15:18 upstream 5200f5f493f7 55156e84 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/05/18 04:39 upstream e5d505e3664b de5aae85 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/05/16 22:58 upstream 6916d5703ddf de5aae85 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/05/15 22:40 upstream d458a240344c 81fb92f3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/05/15 09:04 upstream 70eda68668d1 9cd3beaa .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/05/15 07:52 upstream 70eda68668d1 6ccb967e .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/05/14 18:15 upstream 66182ca873a4 6ccb967e .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/05/13 23:07 upstream e1914add2799 6ccb967e .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/05/13 23:06 upstream e1914add2799 6ccb967e .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/05/13 09:58 upstream 1d5dcaa3bd65 fec2a7ee .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/05/12 20:16 upstream c21b90f77687 a0949470 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/05/12 18:48 upstream c21b90f77687 07aeade5 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/05/12 09:19 upstream 50897c955902 07aeade5 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/05/11 19:51 upstream 5d6919055dec d168f260 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/05/11 07:15 upstream 5d6919055dec 845acb1c .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/05/10 22:44 upstream 5d6919055dec 29233ece .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/05/10 10:04 upstream 1bfaee9d3351 29233ece .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/05/09 20:01 upstream e92b2872d0b1 29233ece .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/05/09 04:08 upstream 27a26ccfd528 29233ece .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/05/09 04:07 upstream 27a26ccfd528 29233ece .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/05/08 15:17 upstream 917719c412c4 b2988c17 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/05/08 02:21 upstream fcee7d82f27d 5633175a .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/05/07 23:22 upstream 8ab992f815d6 cbf9e0fc .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/05/07 06:47 upstream 5862221fdded f250db59 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/03/10 03:44 upstream 1f318b96cc84 6972f302 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2026/01/14 08:34 upstream c537e12daeec d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2023/12/08 12:55 upstream 5e3f5b81de80 28b24332 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
2023/11/23 22:26 upstream d3fa86b1a7b4 5b429f39 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in shmem_file_splice_read / shmem_file_splice_read
* Struck through repros no longer work on HEAD.