Hello, When using Syzkaller to fuzz the latest Linux kernel, the following crash was triggered. HEAD commit: a7904a538933 Linux 5.16-rc6 git tree: upstream console output: KCSAN: data-race in step_into / vfs_unlink kernel config: https://paste.ubuntu.com/p/QB39MJKWKb/plain/ Syzlang reproducer: https://paste.ubuntu.com/p/qQPrVRrYfb/plain/ If you fix this issue, please add the following tag to the commit: Reported-by: Hypericum <hypericumperforatum4444@xxxxxxxxx> I think the program data race at the both reading and read/write at the dentry->d_flags reproducer log: https://paste.ubuntu.com/p/2xsqF6W3sB/plain/ reproducer report: ================================================================== BUG: KCSAN: data-race in step_into / vfs_unlink read-write to 0xffff88810a3899c0 of 4 bytes by task 5771 on cpu 1: dont_mount include/linux/dcache.h:358 [inline] vfs_unlink+0x28e/0x440 fs/namei.c:4102 do_unlinkat+0x278/0x540 fs/namei.c:4167 __do_sys_unlink fs/namei.c:4215 [inline] __se_sys_unlink fs/namei.c:4213 [inline] __x64_sys_unlink+0x2c/0x30 fs/namei.c:4213 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae read to 0xffff88810a3899c0 of 4 bytes by task 1537 on cpu 5: __follow_mount_rcu fs/namei.c:1429 [inline] handle_mounts fs/namei.c:1486 [inline] step_into+0xf4/0xea0 fs/namei.c:1800 walk_component+0x1a1/0x360 fs/namei.c:1976 lookup_last fs/namei.c:2425 [inline] path_lookupat+0x12d/0x3c0 fs/namei.c:2449 filename_lookup+0x130/0x310 fs/namei.c:2478 user_path_at_empty+0x3e/0x110 fs/namei.c:2801 do_readlinkat+0x97/0x210 fs/stat.c:443 __do_sys_readlink fs/stat.c:476 [inline] __se_sys_readlink fs/stat.c:473 [inline] __x64_sys_readlink+0x43/0x50 fs/stat.c:473 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae value changed: 0x00600008 -> 0x00008008 Reported by Kernel Concurrency Sanitizer on: CPU: 5 PID: 1537 Comm: systemd-udevd Not tainted 5.16.0-rc8+ #11 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014 ==================================================================
