should_fail_usercopy+0x1a/0x20 lib/fault-inject-usercopy.c:37 copy_from_user_iter lib/iov_iter.c:50 [inline] iterate_ubuf include/linux/iov_iter.h:29 [inline] iterate_and_advance2 include/linux/iov_iter.h:245 [inline] iterate_and_advance include/linux/iov_iter.h:271 [inline] __copy_from_iter lib/iov_iter.c:268 [inline] copy_page_from_iter_atomic+0x237/0xd80 lib/iov_iter.c:500 generic_perform_write+0x20c/0x410 mm/filemap.c:3926 ================================================================== BUG: KCSAN: data-race in data_push_tail / string write to 0xffffffff86ebf30a of 1 bytes by task 14393 on cpu 1: string_nocheck lib/vsprintf.c:650 [inline] string+0x16c/0x200 lib/vsprintf.c:728 vsnprintf+0xa09/0xe20 lib/vsprintf.c:2819 vscnprintf+0x42/0x80 lib/vsprintf.c:2925 printk_sprint+0x30/0x2d0 kernel/printk/printk.c:2124 vprintk_store+0x56f/0x800 kernel/printk/printk.c:2238 vprintk_emit+0xd0/0x5d0 kernel/printk/printk.c:2284 vprintk_default+0x26/0x30 kernel/printk/printk.c:2318 vprintk+0x71/0x80 kernel/printk/printk_safe.c:45 _printk+0x7a/0xa0 kernel/printk/printk.c:2328 set_capacity_and_notify+0x11d/0x170 block/genhd.c:86 loop_set_size+0x2e/0x70 drivers/block/loop.c:237 loop_configure+0xaf9/0xca0 drivers/block/loop.c:1100 lo_ioctl+0x682/0x12e0 blkdev_ioctl+0x375/0x460 block/ioctl.c:633 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:871 [inline] __se_sys_ioctl+0xcf/0x140 fs/ioctl.c:857 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:857 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x63/0x6b read to 0xffffffff86ebf308 of 8 bytes by task 14390 on cpu 0: data_make_reusable kernel/printk/printk_ringbuffer.c:590 [inline] data_push_tail+0x102/0x430 kernel/printk/printk_ringbuffer.c:675 data_alloc+0xbe/0x2c0 kernel/printk/printk_ringbuffer.c:1046 prb_reserve+0x893/0xbc0 kernel/printk/printk_ringbuffer.c:1555 vprintk_store+0x53e/0x800 kernel/printk/printk.c:2228 vprintk_emit+0xd0/0x5d0 kernel/printk/printk.c:2284 vprintk_default+0x26/0x30 kernel/printk/printk.c:2318 vprintk+0x71/0x80 kernel/printk/printk_safe.c:45 _printk+0x7a/0xa0 kernel/printk/printk.c:2328 printk_stack_address arch/x86/kernel/dumpstack.c:72 [inline] show_trace_log_lvl+0x42e/0x510 arch/x86/kernel/dumpstack.c:285 __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xda/0x130 lib/dump_stack.c:106 dump_stack+0x15/0x20 lib/dump_stack.c:113 fail_dump lib/fault-inject.c:52 [inline] should_fail_ex+0x21f/0x230 lib/fault-inject.c:153 should_fail+0xb/0x10 lib/fault-inject.c:163 should_fail_usercopy+0x1a/0x20 lib/fault-inject-usercopy.c:37 copy_from_user_iter lib/iov_iter.c:50 [inline] iterate_ubuf include/linux/iov_iter.h:29 [inline] iterate_and_advance2 include/linux/iov_iter.h:245 [inline] iterate_and_advance include/linux/iov_iter.h:271 [inline] __copy_from_iter lib/iov_iter.c:268 [inline] copy_page_from_iter_atomic+0x237/0xd80 lib/iov_iter.c:500 generic_perform_write+0x20c/0x410 mm/filemap.c:3926 shmem_file_write_iter+0xc8/0xe0 mm/shmem.c:2878 call_write_iter include/linux/fs.h:2020 [inline] new_sync_write fs/read_write.c:491 [inline] vfs_write+0x48a/0x790 fs/read_write.c:584 ksys_write+0xeb/0x1a0 fs/read_write.c:637 __do_sys_write fs/read_write.c:649 [inline] __se_sys_write fs/read_write.c:646 [inline] __x64_sys_write+0x42/0x50 fs/read_write.c:646 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x63/0x6b value changed: 0x00000001000069c5 -> 0x64203a33706f6f6c Reported by Kernel Concurrency Sanitizer on: CPU: 0 PID: 14390 Comm: syz-executor.2 Not tainted 6.7.0-rc5-syzkaller-00125-gc7402612e2e6 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023 ================================================================== shmem_file_write_iter+0xc8/0xe0 mm/shmem.c:2878 call_write_iter include/linux/fs.h:2020 [inline] new_sync_write fs/read_write.c:491 [inline] vfs_write+0x48a/0x790 fs/read_write.c:584 ksys_write+0xeb/0x1a0 fs/read_write.c:637 __do_sys_write fs/read_write.c:649 [inline] __se_sys_write fs/read_write.c:646 [inline] __x64_sys_write+0x42/0x50 fs/read_write.c:646 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x63/0x6b RIP: 0033:0x7fbbe665e8ef Code: 89 54 24 18 48 89 74 24 10 89 7c 24 08 e8 b9 80 02 00 48 8b 54 24 18 48 8b 74 24 10 41 89 c0 8b 7c 24 08 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 31 44 89 c7 48 89 44 24 08 e8 0c 81 02 00 48 RSP: 002b:00007fbbe59e1e70 EFLAGS: 00000293 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000040000 RCX: 00007fbbe665e8ef RDX: 0000000000040000 RSI: 00007fbbdd5c2000 RDI: 0000000000000004 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000402 R10: 0000000020000502 R11: 0000000000000293 R12: 0000000000000004 R13: 00007fbbe59e1f3c R14: 00007fbbe59e1f40 R15: 00007fbbdd5c2000 loop2: detected capacity change from 0 to 512