CPU: 1 UID: 0 PID: 11538 Comm: syz.1.2448 Not tainted 6.16.0-rc2-syzkaller-00231-g75f5f23f8787 #0 PREEMPT(voluntary) ================================================================== BUG: KCSAN: data-race in data_alloc / data_push_tail write to 0xffffffff88e5e5f8 of 8 bytes by task 11540 on cpu 0: data_alloc+0x203/0x2b0 kernel/printk/printk_ringbuffer.c:1082 prb_reserve+0x808/0xaf0 kernel/printk/printk_ringbuffer.c:1669 vprintk_store+0x56d/0x860 kernel/printk/printk.c:2326 vprintk_emit+0x178/0x650 kernel/printk/printk.c:2426 vprintk_default+0x26/0x30 kernel/printk/printk.c:2465 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82 _printk+0x79/0xa0 kernel/printk/printk.c:2475 fail_dump lib/fault-inject.c:66 [inline] should_fail_ex+0x24d/0x280 lib/fault-inject.c:174 should_fail+0xb/0x20 lib/fault-inject.c:184 should_fail_usercopy+0x1a/0x20 lib/fault-inject-usercopy.c:37 _inline_copy_from_user include/linux/uaccess.h:163 [inline] _copy_from_user+0x1c/0xb0 lib/usercopy.c:18 copy_from_user include/linux/uaccess.h:212 [inline] restore_altstack+0x4b/0x2d0 kernel/signal.c:4459 __ia32_sys_rt_sigreturn+0xdc/0x350 arch/x86/kernel/signal_64.c:265 x64_sys_call+0x2e8a/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:16 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f read to 0xffffffff88e5e5f8 of 8 bytes by task 11538 on cpu 1: data_make_reusable kernel/printk/printk_ringbuffer.c:594 [inline] data_push_tail+0xfd/0x420 kernel/printk/printk_ringbuffer.c:679 data_alloc+0xbf/0x2b0 kernel/printk/printk_ringbuffer.c:1054 prb_reserve+0x808/0xaf0 kernel/printk/printk_ringbuffer.c:1669 vprintk_store+0x56d/0x860 kernel/printk/printk.c:2326 vprintk_emit+0x178/0x650 kernel/printk/printk.c:2426 vprintk_default+0x26/0x30 kernel/printk/printk.c:2465 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82 _printk+0x79/0xa0 kernel/printk/printk.c:2475 dump_stack_print_info+0xee/0x1b0 lib/dump_stack.c:57 __dump_stack+0x11/0x30 lib/dump_stack.c:93 dump_stack_lvl+0xe8/0x140 lib/dump_stack.c:120 dump_stack+0x15/0x1b lib/dump_stack.c:129 fail_dump lib/fault-inject.c:73 [inline] should_fail_ex+0x265/0x280 lib/fault-inject.c:174 should_fail+0xb/0x20 lib/fault-inject.c:184 should_fail_usercopy+0x1a/0x20 lib/fault-inject-usercopy.c:37 strncpy_from_user+0x25/0x230 lib/strncpy_from_user.c:118 getname_flags+0xae/0x3b0 fs/namei.c:157 getname include/linux/fs.h:2907 [inline] do_sys_openat2+0x60/0x110 fs/open.c:1431 do_sys_open fs/open.c:1452 [inline] __do_sys_openat fs/open.c:1468 [inline] __se_sys_openat fs/open.c:1463 [inline] __x64_sys_openat+0xf2/0x120 fs/open.c:1463 x64_sys_call+0x1af/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:258 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f value changed: 0x00000000ffffeafc -> 0x00000000fffff82c Reported by Kernel Concurrency Sanitizer on: CPU: 1 UID: 0 PID: 11538 Comm: syz.1.2448 Not tainted 6.16.0-rc2-syzkaller-00231-g75f5f23f8787 #0 PREEMPT(voluntary) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 ================================================================== Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Call Trace: __dump_stack+0x1d/0x30 lib/dump_stack.c:94 dump_stack_lvl+0xe8/0x140 lib/dump_stack.c:120 dump_stack+0x15/0x1b lib/dump_stack.c:129 fail_dump lib/fault-inject.c:73 [inline] should_fail_ex+0x265/0x280 lib/fault-inject.c:174 should_fail+0xb/0x20 lib/fault-inject.c:184 should_fail_usercopy+0x1a/0x20 lib/fault-inject-usercopy.c:37 strncpy_from_user+0x25/0x230 lib/strncpy_from_user.c:118 getname_flags+0xae/0x3b0 fs/namei.c:157 getname include/linux/fs.h:2907 [inline] do_sys_openat2+0x60/0x110 fs/open.c:1431 do_sys_open fs/open.c:1452 [inline] __do_sys_openat fs/open.c:1468 [inline] __se_sys_openat fs/open.c:1463 [inline] __x64_sys_openat+0xf2/0x120 fs/open.c:1463 x64_sys_call+0x1af/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:258 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f45363ce929 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f4534a37038 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007f45365f5fa0 RCX: 00007f45363ce929 RDX: 0000000000000000 RSI: 0000200000000000 RDI: ffffffffffffff9c RBP: 00007f4534a37090 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 R13: 0000000000000000 R14: 00007f45365f5fa0 R15: 00007ffed3e61f88