syzbot


KCSAN: data-race in __kernel_write_iter / set_task_ioprio (3)

Status: moderation: reported on 2025/12/26 20:02
Subsystems: block
[Documentation on labels]
Reported-by: syzbot+b9b6442ccf519f794a7e@syzkaller.appspotmail.com
First crash: 53d, last: 4d21h
Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in __kernel_write_iter / set_task_ioprio (2) block 6 1 263d 263d 0/29 auto-obsoleted due to no activity on 2025/07/26 03:33
upstream KCSAN: data-race in __kernel_write_iter / set_task_ioprio block 6 7 343d 483d 0/29 auto-obsoleted due to no activity on 2025/05/06 16:02

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

write to 0xffff88810d84d9e8 of 8 bytes by task 9423 on cpu 0:
 set_task_ioprio+0x24e/0x270 block/blk-ioc.c:280
 __do_sys_ioprio_set block/ioprio.c:121 [inline]
 __se_sys_ioprio_set+0x24f/0x5a0 block/ioprio.c:65
 __x64_sys_ioprio_set+0x43/0x50 block/ioprio.c:65
 x64_sys_call+0x2bbf/0x3020 arch/x86/include/generated/asm/syscalls_64.h:252
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x370 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88810d84d9e8 of 8 bytes by task 9381 on cpu 1:
 __get_task_ioprio include/linux/ioprio.h:59 [inline]
 get_current_ioprio include/linux/ioprio.h:84 [inline]
 init_sync_kiocb include/linux/fs.h:2194 [inline]
 __kernel_write_iter+0xdb/0x590 fs/read_write.c:619
 dump_emit_page fs/coredump.c:1299 [inline]
 dump_user_range+0xa7d/0xdb0 fs/coredump.c:1373
 elf_core_dump+0x21a2/0x2330 fs/binfmt_elf.c:2111
 coredump_write+0xacf/0xdf0 fs/coredump.c:1050
 do_coredump fs/coredump.c:1127 [inline]
 vfs_coredump+0x26c7/0x3130 fs/coredump.c:1201
 get_signal+0xd7b/0xf60 kernel/signal.c:3019
 arch_do_signal_or_restart+0x96/0x450 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:64 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:98 [inline]
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 irqentry_exit_to_user_mode_prepare include/linux/irq-entry-common.h:270 [inline]
 irqentry_exit_to_user_mode include/linux/irq-entry-common.h:339 [inline]
 irqentry_exit+0xf7/0x520 kernel/entry/common.c:219
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618

value changed: 0x0000000000000000 -> 0xffff88811c247c30

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 9381 Comm: syz.5.1260 Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
==================================================================

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/02/13 16:40 upstream 37a93dd5c49b 6a673c50 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __kernel_write_iter / set_task_ioprio
2025/12/26 20:01 upstream ccd1cdca5cd4 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __kernel_write_iter / set_task_ioprio
* Struck through repros no longer work on HEAD.