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KCSAN: data-race in _copy_from_iter / _copy_from_iter (5)

Status: moderation: reported on 2025/03/31 12:44
Subsystems: mm
[Documentation on labels]
Reported-by: syzbot+b598ec189233b099946c@syzkaller.appspotmail.com
First crash: 420d, last: 8d00h
▶ ▼ ✨ AI Jobs (3)
ID Workflow Result Correct Bug Created Started Finished Revision Error
eba1cd8b-57ce-40e5-8b2b-1426c5cfdaf2 assessment-security 💥 KCSAN: data-race in _copy_from_iter / _copy_from_iter (5) 2026/05/14 11:56 2026/05/14 11:56 2026/05/14 11:58 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/9803ea525762e60e30bcf42ac70c027c2cb50de5" "-s" "bzImage" "compile_commands.json"]: exit status 2 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/316e237849c78635c7c5ae4b5398d0fa5c963d95/= -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/316e237849c78635c7c5ae4b5398d0fa5c963d95/arch/x86/include -I./arch/x86/include/generated -I/app/workdir/cache/src/316e237849c78635c7c5ae4b5398d0fa5c963d95/include -I./include -I/app/workdir/cache/src/316e237849c78635c7c5ae4b5398d0fa5c963d95/arch/x86/include/uapi -I./arch/x86/include/generated/uapi -I/app/workdir/cache/src/316e237849c78635c7c5ae4b5398d0fa5c963d95/include/uapi -I./include/generated/uapi -include /app/workdir/cache/src/316e237849c78635c7c5ae4b5398d0fa5c963d95/include/linux/compiler-version.h -include /app/workdir/cache/src/316e237849c78635c7c5ae4b5398d0fa5c963d95/include/linux/kconfig.h -include /app/workdir/cache/src/316e237849c78635c7c5ae4b5398d0fa5c963d95/include/linux/compiler_types.h -D__KERNEL__ -I/app/workdir/cache/src/316e237849c78635c7c5ae4b5398d0fa5c963d95/net/x25 -Inet/x25 -DKBUILD_MODFILE=\"net/x25/x25\" -DKBUILD_BASENAME=\"x25_in\" -DKBUILD_MODNAME=\"x25\" -D__KBUILD_MODNAME=x25 -c -Wp,-MMD,net/x25/.x25_in.o.d -fcolor-diagnostics -o net/x25/x25_in.o /app/workdir/cache/src/316e237849c78635c7c5ae4b5398d0fa5c963d95/net/x25/x25_in.c S
55a5450d-b1ac-403b-a0a8-b2becaa8c733 repro ❓ KCSAN: data-race in _copy_from_iter / _copy_from_iter (5) 2026/03/06 16:14 2026/03/06 16:14 2026/03/06 16:21 31e9c887f7dc24e04b3ca70d0d54fc34141844b0
e400f300-e8c5-4f1a-a759-e3b36fb93562 assessment-kcsan Benign: ✅ ❓ KCSAN: data-race in _copy_from_iter / _copy_from_iter (5) 2026/01/09 17:27 2026/01/09 17:27 2026/01/09 17:47 7519916073b761ced56a7b15fdeeb4674e8dc125
▶ ▼ Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in _copy_from_iter / _copy_from_iter mm 6 8 1039d 1084d 0/29 auto-obsoleted due to no activity on 2023/08/24 22:03
upstream KCSAN: data-race in _copy_from_iter / _copy_from_iter (4) mm 6 7 487d 563d 0/29 auto-obsoleted due to no activity on 2025/03/20 10:28
upstream KCSAN: data-race in _copy_from_iter / _copy_from_iter (3) mm 6 12 643d 756d 0/29 auto-obsoleted due to no activity on 2024/09/24 07:08
upstream KCSAN: data-race in _copy_from_iter / _copy_from_iter (2) mm 6 18 816d 897d 0/29 auto-obsoleted due to no activity on 2024/04/04 01:00

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

write to 0xffff88811c7f7000 of 4096 bytes by task 5273 on cpu 1:
 instrument_copy_from_user_before include/linux/instrumented.h:147 [inline]
 copy_from_user_iter lib/iov_iter.c:66 [inline]
 iterate_ubuf include/linux/iov_iter.h:30 [inline]
 iterate_and_advance2 include/linux/iov_iter.h:302 [inline]
 iterate_and_advance include/linux/iov_iter.h:330 [inline]
 __copy_from_iter lib/iov_iter.c:261 [inline]
 _copy_from_iter+0x106/0xea0 lib/iov_iter.c:272
 copy_page_from_iter+0x161/0x1f0 lib/iov_iter.c:434
 process_vm_rw_pages mm/process_vm_access.c:43 [inline]
 process_vm_rw_single_vec mm/process_vm_access.c:118 [inline]
 process_vm_rw_core mm/process_vm_access.c:216 [inline]
 process_vm_rw+0x6ad/0x9c0 mm/process_vm_access.c:284
 __do_sys_process_vm_writev mm/process_vm_access.c:304 [inline]
 __se_sys_process_vm_writev mm/process_vm_access.c:299 [inline]
 __x64_sys_process_vm_writev+0x78/0x90 mm/process_vm_access.c:299
 x64_sys_call+0x1592/0x3020 arch/x86/include/generated/asm/syscalls_64.h:312
 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 0xffff88811c7f7000 of 4096 bytes by task 5272 on cpu 0:
 instrument_copy_from_user_before include/linux/instrumented.h:147 [inline]
 copy_from_user_iter lib/iov_iter.c:66 [inline]
 iterate_ubuf include/linux/iov_iter.h:30 [inline]
 iterate_and_advance2 include/linux/iov_iter.h:302 [inline]
 iterate_and_advance include/linux/iov_iter.h:330 [inline]
 __copy_from_iter lib/iov_iter.c:261 [inline]
 _copy_from_iter+0x106/0xea0 lib/iov_iter.c:272
 copy_page_from_iter+0x161/0x1f0 lib/iov_iter.c:434
 process_vm_rw_pages mm/process_vm_access.c:43 [inline]
 process_vm_rw_single_vec mm/process_vm_access.c:118 [inline]
 process_vm_rw_core mm/process_vm_access.c:216 [inline]
 process_vm_rw+0x6ad/0x9c0 mm/process_vm_access.c:284
 __do_sys_process_vm_writev mm/process_vm_access.c:304 [inline]
 __se_sys_process_vm_writev mm/process_vm_access.c:299 [inline]
 __x64_sys_process_vm_writev+0x78/0x90 mm/process_vm_access.c:299
 x64_sys_call+0x1592/0x3020 arch/x86/include/generated/asm/syscalls_64.h:312
 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

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 5272 Comm: syz.5.385 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
==================================================================

Crashes (148):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/17 17:17 upstream 6916d5703ddf de5aae85 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/05/16 18:52 upstream d458a240344c a15a64a6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/04/26 11:00 upstream 897d54018cc9 9c2d0995 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/03/31 07:46 upstream d0c3bcd5b897 d0af506e .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/03/28 08:52 upstream 7df48e363130 356bdfc9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/03/25 16:55 upstream bbeb83d3182a 8ee77f7d .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/03/21 03:03 upstream 0e4f8f1a3d08 ac6f1dff .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/03/12 19:58 upstream 80234b5ab240 4efadf07 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/03/10 00:19 upstream 1f318b96cc84 176bead5 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/03/08 09:48 upstream c23719abc330 5cb44a80 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/02/28 17:42 upstream 4d349ee5c778 43249bac .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/02/27 18:30 upstream a75cb869a8cc 2cf092b8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/02/22 11:54 upstream fa5c82f4d2bb 6e7b5511 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/02/19 17:23 upstream 956b9cbd7f15 746545b8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/02/18 09:23 upstream 2961f841b025 39751c21 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/02/16 20:43 upstream 0f2acd3148e0 5d52cba5 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/02/12 21:38 upstream 37a93dd5c49b 504cb1bf .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/02/11 09:58 upstream dc855b77719f 441e25b7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/02/08 00:21 upstream e7aa57247700 4c131dc4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/02/07 04:57 upstream 2687c848e578 f20fc9f9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/02/06 16:06 upstream b7ff7151e653 97745f52 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/02/06 01:50 upstream 8fdb05de0e2d f03c4191 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/02/05 12:02 upstream f14faaf3a1fb 4936e85c .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/02/05 06:45 upstream f14faaf3a1fb ea10c935 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/02/05 01:09 upstream 5fd0a1df5d05 ea10c935 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/02/03 17:24 upstream 6bd9ed02871f 6df4c87a .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/02/03 04:36 upstream dee65f79364c d78927dd .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/02/02 17:15 upstream 18f7fcd5e69a 018ebef2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/02/02 00:24 upstream 9f2693489ef8 6b8752f2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/02/01 07:57 upstream ad9a728a3388 6b8752f2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/01/31 21:04 upstream ad9a728a3388 afc0c4d4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/01/31 08:50 upstream 283073725700 c75a2f6e .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/01/30 22:49 upstream 4d310797262f ae7dc18c .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/01/29 21:32 upstream 8dfce8991b95 aeb6fdd5 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/01/28 11:58 upstream 1f97d9dcf536 004c195c .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/01/28 05:09 upstream 1f97d9dcf536 3029c699 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/01/27 06:17 upstream fcb70a56f4d8 efb3e894 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/01/26 04:26 upstream 023777797472 55756628 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/01/24 06:05 upstream 5bde837031a3 4f25b9b4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/01/22 12:21 upstream a66191c590b3 a16aed1d .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/01/22 03:03 upstream cf38b2340c0e 8fc37797 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/01/21 18:12 upstream 6c790212c588 8fc37797 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/01/21 08:22 upstream 6c790212c588 6f1aa2f9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/01/20 11:49 upstream 24d479d26b25 06648d9c .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/01/20 05:20 upstream 24d479d26b25 572effc1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/01/19 14:08 upstream 24d479d26b25 a9fc5226 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/01/18 04:58 upstream d12453c7e281 20d37d28 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/01/18 01:20 upstream d3eeb99bbc99 20d37d28 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/01/15 15:46 upstream 944aacb68baf d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/01/15 05:33 upstream e0d4140e8043 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2026/01/08 22:17 upstream 79b95d74470d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
2025/03/31 12:43 upstream 4e82c87058f4 d3999433 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in _copy_from_iter / _copy_from_iter
* Struck through repros no longer work on HEAD.