syzbot

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BUG: KCSAN: data-race in capable_wrt_inode_uidgid / prepare_signal

write to 0xffff8881001c60ec of 4 bytes by task 651 on cpu 0:
 ns_capable_common kernel/capability.c:377 [inline]
 ns_capable kernel/capability.c:396 [inline]
 capable_wrt_inode_uidgid+0xa5/0x140 kernel/capability.c:509
 generic_permission+0xe7/0x420 fs/namei.c:399
 kernfs_iop_permission+0x173/0x180 fs/kernfs/inode.c:291
 do_inode_permission fs/namei.c:446 [inline]
 inode_permission+0x18c/0x290 fs/namei.c:513
 may_lookup fs/namei.c:1660 [inline]
 link_path_walk+0x1c2/0x780 fs/namei.c:2212
 path_openat+0x1a0/0x20b0 fs/namei.c:3496
 do_filp_open+0xd9/0x1f0 fs/namei.c:3527
 do_sys_openat2+0xa3/0x250 fs/open.c:1187
 do_sys_open fs/open.c:1203 [inline]
 __do_sys_openat fs/open.c:1219 [inline]
 __se_sys_openat fs/open.c:1214 [inline]
 __x64_sys_openat+0xef/0x110 fs/open.c:1214
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff8881001c60ec of 4 bytes by task 641 on cpu 1:
 sig_task_ignored kernel/signal.c:94 [inline]
 sig_ignored kernel/signal.c:119 [inline]
 prepare_signal+0x872/0xd80 kernel/signal.c:962
 __send_signal+0x64/0x760 kernel/signal.c:1082
 send_signal+0x38e/0x3d0 kernel/signal.c:1242
 __group_send_sig_info kernel/signal.c:1281 [inline]
 do_notify_parent_cldstop+0x222/0x280 kernel/signal.c:2068
 ptrace_stop+0x2e2/0x670 kernel/signal.c:2202
 ptrace_signal kernel/signal.c:2491 [inline]
 get_signal+0xbb3/0x15d0 kernel/signal.c:2669
 arch_do_signal_or_restart+0x2a/0x220 arch/x86/kernel/signal.c:789
 handle_signal_work kernel/entry/common.c:147 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:171 [inline]
 exit_to_user_mode_prepare+0x109/0x190 kernel/entry/common.c:208
 __syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
 syscall_exit_to_user_mode+0x20/0x40 kernel/entry/common.c:301
 do_syscall_64+0x56/0x90 arch/x86/entry/common.c:57
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 641 Comm: syz-executor.4 Not tainted 5.12.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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