syzbot

 sign-in | mailing list | source | docs | 🏰
🐞 Open [1344]
≡ Subsystems
🐞 Fixed [7090]
🐞 Invalid [18704]
⬇ Missing Backports [221]
≡ Crashes
Kernel Health Bugs/Month Bug Lifetimes Fuzzing
Total Repo Heatmap Subsystems Heatmap
✨ AI
💬 Send us feedback

KCSAN: data-race in generic_fillattr / inode_set_ctime_current (4)

Status: moderation: reported on 2026/05/11 10:21
Subsystems: fs
Labels: race:benign
[Documentation on labels]
Reported-by: syzbot+c886d58659d9942bf21f@syzkaller.appspotmail.com
First crash: 3d03h, last: 3d03h
▶ ▼ ✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision Error
4ab1dfb6-fb24-46ee-83b7-71dddf0a22fc assessment-security 💥 KCSAN: data-race in generic_fillattr / inode_set_ctime_current (4) 2026/05/14 09:25 2026/05/14 09:25 2026/05/14 09:28 6ccb967e465e832a7bfd7a116ad00d52a0923a5d failed to run ["make" "KERNELVERSION=syzkaller" "KERNELRELEASE=syzkaller" "LOCALVERSION=-syzkaller" "-j" "32" "ARCH=x86_64" "CC=ccache clang" "LD=ld.lld" "O=/app/workdir/cache/build/45776d348471d68a01336c8a8bda9831bd890ca3" "-s" "bzImage" "compile_commands.json"]: exit status 2 Root cause: error: unable to open output file 'drivers/net/vxlan/vxlan_core.o': 'No such file or directory' error: unable to open output file 'drivers/usb/isp1760/isp1760-core.o': 'No such file or directory' fixdep: not all data was written to the output make[4]: *** [/app/workdir/cache/src/ecd8bb68855fdd08aa08215ac485989bac875215/scripts/Makefile.build:289: kernel/elfcorehdr.o] Error 1 make[4]: *** Deleting file 'kernel/elfcorehdr.o' make[3]: *** [/app/workdir/cache/src/ecd8bb68855fdd08aa08215ac485989bac875215/scripts/Makefile.build:548: kernel] Error 2 make[3]: *** Waiting for unfinished jobs.... fatal error: error in backend: IO failure on output stream: No space left on device PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace, preprocessed source, and associated run script. Stack dump: 0. Program arguments: /usr/bin/clang --target=x86_64-linux-gnu -fintegrated-as -Werror=unknown-warning-option -Werror=ignored-optimization-argument -Werror=option-ignored -Werror=unused-command-line-argument -fmacro-prefix-map=/app/workdir/cache/src/ecd8bb68855fdd08aa08215ac485989bac875215/= -fshort-wchar -funsigned-char -fno-common -fno-PIE -fno-strict-aliasing -std=gnu11 -fms-extensions -Wno-gnu -Wno-microsoft-anon-tag -mno-sse -mno-mmx -mno-sse2 -mno-3dnow -mno-avx -mno-sse4a -fcf-protection=branch -fno-jump-tables -m64 -falign-loops=1 -mno-80387 -mno-fp-ret-in-387 -mstack-alignment=8 -mskip-rax-setup -march=x86-64 -mtune=generic -mno-red-zone -mcmodel=kernel -mstack-protector-guard-reg=gs -mstack-protector-guard-symbol=__ref_stack_chk_guard -Wno-sign-compare -fno-asynchronous-unwind-tables -mretpoline-external-thunk -mindirect-branch-cs-prefix -mfunction-return=thunk-extern -fpatchable-function-entry=16,16 -fno-delete-null-pointer-checks -O2 -fstack-protector-strong -fomit-frame-pointer -ftrivial-auto-var-init=zero -fno-stack-clash-protection -falign-functions=16 -fstrict-flex-arrays=3 -fno-strict-overflow -fno-stack-check -fno-builtin-wcslen -Wall -Wextra -Wundef -Werror=implicit-function-declaration -Werror=implicit-int -Werror=return-type -Werror=strict-prototypes -Wno-format-security -Wno-trigraphs -Wno-frame-address -Wno-address-of-packed-member -Wmissing-declarations -Wmissing-prototypes -Wframe-larger-than=2048 -Wno-format-overflow-non-kprintf -Wno-format-truncation-non-kprintf -Wno-default-const-init-unsafe -Wno-type-limits -Wno-pointer-sign -Wcast-function-type -Wno-unterminated-string-initialization -Wimplicit-fallthrough -Werror=date-time -Werror=incompatible-pointer-types -Wenum-conversion -Wunused -Wno-unused-but-set-variable -Wno-unused-const-variable -Wno-format-overflow -Wno-override-init -Wno-pointer-to-enum-cast -Wno-tautological-constant-out-of-range-compare -Wno-unaligned-access -Wno-enum-compare-conditional -Wno-missing-field-initializers -Wno-shift-negative-value -Wno-enum-enum-conversion -Wno-sign-compare -Wno-unused-parameter -g -gdwarf-4 -fsanitize-coverage=trace-pc -fsanitize-coverage=trace-cmp -fsanitize=thread -fno-optimize-sibling-calls -mllvm -tsan-compound-read-before-write=1 -mllvm -tsan-distinguish-volatile=1 -mllvm -tsan-instrument-func-entry-exit=0 -fdebug-info-for-profiling -mllvm -enable-fs-discriminator=true -mllvm -improved-fs-discriminator=true -fbasic-block-address-map -nostdinc -I/app/workdir/cache/src/ecd8bb68855fdd08aa08215ac485989bac875215/arch/x86/include -I./arch/x86/include/generated -I/app/workdir/cache/src/ecd8bb68855fdd08aa08215ac485989bac875215/include -I./include -I/app/workdir/cache/src/ecd8bb68855fdd08aa08215ac485989bac875215/arch/x86/include/uapi -I./arch/x86/include/generated/uapi -I/app/workdir/cache/src/ecd8bb68855fdd08aa08215ac485989bac875215/include/uapi -I./include/generated/uapi -include /app/workdir/cache/src/ecd8bb68855fdd08aa08215ac4859
90561fef-facb-4e9e-aa98-08c305242379 assessment-kcsan Benign: ✅ ❓ KCSAN: data-race in generic_fillattr / inode_set_ctime_current (4) 2026/05/11 10:20 2026/05/11 10:20 2026/05/11 10:43 fc6e6eac62ee224ed1276afaf24df37313ad0a0c
▶ ▼ Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in generic_fillattr / inode_set_ctime_current (2) fs 6 55 564d 697d 0/29 auto-obsoleted due to no activity on 2024/12/14 19:09
upstream KCSAN: data-race in generic_fillattr / inode_set_ctime_current fs 6 62 733d 886d 0/29 auto-obsoleted due to no activity on 2024/06/14 18:17
upstream KCSAN: data-race in generic_fillattr / inode_set_ctime_current (3) fs 6 2 67d 81d 0/29 auto-obsoleted due to no activity on 2026/05/02 22:36

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

write to 0xffff88810b1aa940 of 4 bytes by task 13758 on cpu 0:
 inode_set_ctime_to_ts fs/inode.c:2772 [inline]
 inode_set_ctime_current+0x256/0x8c0 fs/inode.c:2835
 __simple_unlink fs/libfs.c:792 [inline]
 simple_unlink+0x2d/0x80 fs/libfs.c:807
 shmem_unlink+0x12d/0x140 mm/shmem.c:3981
 shmem_rename2+0x18e/0x310 mm/shmem.c:4062
 vfs_rename+0x97f/0xad0 fs/namei.c:6054
 filename_renameat2+0x3b6/0x6e0 fs/namei.c:6172
 __do_sys_rename fs/namei.c:6216 [inline]
 __se_sys_rename+0x4a/0x1c0 fs/namei.c:6212
 __x64_sys_rename+0x31/0x40 fs/namei.c:6212
 x64_sys_call+0x2b3/0x3020 arch/x86/include/generated/asm/syscalls_64.h:83
 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

read to 0xffff88810b1aa940 of 4 bytes by task 13781 on cpu 1:
 inode_get_ctime_nsec include/linux/fs.h:1690 [inline]
 inode_get_ctime include/linux/fs.h:1696 [inline]
 generic_fillattr+0x1d1/0x340 fs/stat.c:101
 shmem_getattr+0x181/0x200 mm/shmem.c:1302
 vfs_getattr_nosec+0x146/0x1e0 fs/stat.c:213
 vfs_getattr+0x48/0x60 fs/stat.c:262
 vfs_statx_path+0x28/0x140 fs/stat.c:299
 vfs_statx+0xc4/0x170 fs/stat.c:356
 vfs_fstatat+0x118/0x170 fs/stat.c:373
 __do_sys_newfstatat fs/stat.c:538 [inline]
 __se_sys_newfstatat+0x55/0x3e0 fs/stat.c:532
 __x64_sys_newfstatat+0x55/0x70 fs/stat.c:532
 x64_sys_call+0x2c64/0x3020 arch/x86/include/generated/asm/syscalls_64.h:263
 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: 0x257765c0 -> 0x28725641

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 13781 Comm: udevd 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 (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/11 10:20 upstream 5d6919055dec 845acb1c .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in generic_fillattr / inode_set_ctime_current
* Struck through repros no longer work on HEAD.