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KCSAN: data-race in filemap_splice_read / filemap_splice_read

Status: moderation: reported on 2023/12/07 10:14
Subsystems: ext4
Labels: prio:low
[Documentation on labels]
Reported-by: syzbot+656c0f7422b03843b487@syzkaller.appspotmail.com
First crash: 1076d, last: 8h58m
▶ ▼ ✨ AI Jobs (4)
ID Workflow Result Correct Bug Created Started Finished Revision Error
f310f88c-115a-417f-849e-5bdc9bc38cd4 assessment-security DenialOfService: ❌ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ✅ UserNamespace: ✅ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ KCSAN: data-race in filemap_splice_read / filemap_splice_read 2026/05/30 23:23 2026/05/30 23:23 2026/05/31 00:08 6b4a844333e83556da95d61d7f207e7ef5cd4bc6
ec6b776f-bead-48e0-a393-e7372d8ddae9 assessment-security 💥 KCSAN: data-race in filemap_splice_read / filemap_splice_read 2026/05/14 12:13 2026/05/14 12:13 2026/05/14 12:14 6ccb967e465e832a7bfd7a116ad00d52a0923a5d failed to run ["git" "pull" "origin" "HEAD" "--depth=1" "--allow-unrelated-histories"]: exit status 128 From /app/workdir/repo/linux * branch HEAD -> FETCH_HEAD Updating files: 19% (18429/93697) Updating files: 20% (18740/93697) Updating files: 21% (19677/93697) Updating files: 22% (20614/93697) Updating files: 23% (21551/93697) Updating files: 24% (22488/93697) Updating files: 25% (23425/93697) Updating files: 26% (24362/93697) Updating files: 27% (25299/93697) Updating files: 28% (26236/93697) Updating files: 28% (26922/93697) Updating files: 29% (27173/93697) Updating files: 30% (28110/93697) Updating files: 31% (29047/93697) Updating files: 32% (29984/93697) error: unable to write file drivers/acpi/pptt.c error: unable to write file drivers/acpi/prmt.c error: unable to write file drivers/acpi/proc.c error: unable to write file drivers/acpi/processor_core.c error: unable to write file drivers/acpi/processor_driver.c error: unable to write file drivers/acpi/processor_idle.c error: unable to write file drivers/acpi/processor_pdc.c error: unable to write file drivers/acpi/processor_perflib.c error: unable to write file drivers/acpi/processor_thermal.c error: unable to write file drivers/acpi/processor_throttling.c error: unable to write file drivers/acpi/property.c error: unable to write file drivers/acpi/reboot.c error: unable to write file drivers/acpi/resource.c fatal: cannot create directory at 'drivers/acpi/riscv': No space left on device
470adca6-ae62-4a4f-9dc1-69ec4c363d36 repro ❓ KCSAN: data-race in filemap_splice_read / filemap_splice_read 2026/03/06 16:47 2026/03/06 16:47 2026/03/06 17:02 31e9c887f7dc24e04b3ca70d0d54fc34141844b0
437da85d-cddc-42e6-b056-7d4a29de5f9b assessment-kcsan Benign: ✅ ❓ KCSAN: data-race in filemap_splice_read / filemap_splice_read 2026/01/09 18:53 2026/01/09 18:53 2026/01/09 18:55 7519916073b761ced56a7b15fdeeb4674e8dc125

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

write to 0xffff88811b4712e0 of 8 bytes by task 7035 on cpu 0:
 filemap_splice_read+0x523/0x780 mm/filemap.c:3131
 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 0xffff88811b4712e0 of 8 bytes by task 7036 on cpu 1:
 filemap_splice_read+0x523/0x780 mm/filemap.c:3131
 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: 0x00000000000005da -> 0x00000000000005db

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 7036 Comm: syz.4.1344 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
==================================================================

Crashes (1565):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/06/07 04:13 upstream 979c294509f9 cc095639 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/06/07 01:48 upstream 8e65320d91cd cc095639 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/06/06 01:54 upstream c10130c234c8 cc095639 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/06/05 18:43 upstream ddd664bbff63 48b6c3fa .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/06/04 15:57 upstream ba3e43a9e601 197909be .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/06/02 01:49 upstream e43ffb69e043 1095583b .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/05/28 09:45 upstream eb3f4b7426cf 4c36e7e5 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/05/27 22:41 upstream eb3f4b7426cf 8777bdc3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/05/27 09:03 upstream d60ec36cab33 2b01f00e .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/05/25 16:02 upstream e7ae89a0c97c c69befb3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/05/24 18:54 upstream 4cbfe4502e3d c69befb3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/05/24 05:06 upstream eed108edc117 c69befb3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/05/22 16:04 upstream 45255ea1ca09 5f091fcc .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/05/20 02:14 upstream 27fa82620cba 0909d65f .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/05/18 04:43 upstream e5d505e3664b de5aae85 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/05/14 20:55 upstream 66182ca873a4 6ccb967e .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/05/14 17:08 upstream e1914add2799 6ccb967e .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/05/13 09:41 upstream 1d5dcaa3bd65 fec2a7ee .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/05/12 18:33 upstream c21b90f77687 07aeade5 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/05/11 18:33 upstream 5d6919055dec 845acb1c .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/05/10 21:00 upstream 1bfaee9d3351 29233ece .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/05/08 16:24 upstream 917719c412c4 b2988c17 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/05/07 19:12 upstream 8ab992f815d6 cbf9e0fc .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/05/06 13:19 upstream 74fe02ce122a 1dddfd3d .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/05/05 09:02 upstream c7e4e4d5f7dc a898ba9c .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/05/04 03:15 upstream f377d0025eb0 a0d91488 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/05/03 04:17 upstream 66edb901bf87 a0d91488 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/05/02 15:38 upstream f1a5e78a55eb a0d91488 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/05/02 02:23 upstream 6fe0be6dc7fa 753c55b9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/05/01 13:14 upstream 26fd6bff2c05 753c55b9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/04/30 18:42 upstream e75a43c7cec4 a7464baf .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/04/29 20:54 upstream 57b8e2d666a3 005438fc .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/04/26 08:37 upstream 897d54018cc9 9c2d0995 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/04/24 22:39 upstream dd6c438c3e64 1c2b9291 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/04/23 17:20 upstream 2e6803928193 4c3406dc .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/04/18 23:45 upstream eb5249b12507 303e2802 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/04/13 16:55 upstream 028ef9c96e96 9530ccf9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/04/12 00:52 upstream e753c16cb3dd 38c8e246 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/04/09 10:30 upstream 7f87a5ea75f0 38c8e246 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/04/05 03:44 upstream 3aae9383f42f 4440e7c2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/04/03 16:09 upstream d8a9a4b11a13 4440e7c2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/04/02 22:37 upstream 5619b098e2fb 4440e7c2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/04/01 11:16 upstream dbf00d8d23b4 9a1f7828 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/03/31 06:51 upstream d0c3bcd5b897 d0af506e .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/03/30 08:01 upstream 7aaa8047eafd b5ceaad2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/03/28 04:53 upstream 7df48e363130 356bdfc9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/03/26 19:17 upstream 0138af2472df 766b6434 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/03/26 05:15 upstream d2a43e7f89da c6143aac .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/03/05 11:08 upstream ecc64d2dc9ff a9fe5c9e .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2026/01/09 06:35 upstream 623fb9912f6a d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2023/12/06 14:46 upstream bee0e7762ad2 e3299f55 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
2023/11/28 11:10 upstream df60cee26a2e 9fe51b7c .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in filemap_splice_read / filemap_splice_read
* Struck through repros no longer work on HEAD.