syzbot

==================================================================
BUG: KCSAN: data-race in lookup_user_key / lookup_user_key

write to 0xffff88807d469f98 of 4 bytes by task 18759 on cpu 1:
 get_cred include/linux/cred.h:253 [inline]
 lookup_user_key+0xc6/0xb30 security/keys/process_keys.c:626
 keyctl_update_key+0xc1/0x150 security/keys/keyctl.c:352
 __do_sys_keyctl security/keys/keyctl.c:1726 [inline]
 __se_sys_keyctl security/keys/keyctl.c:1714 [inline]
 __x64_sys_keyctl+0x305/0x3e0 security/keys/keyctl.c:1714
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffff88807d469f98 of 4 bytes by task 18732 on cpu 0:
 get_cred include/linux/cred.h:253 [inline]
 lookup_user_key+0xc6/0xb30 security/keys/process_keys.c:626
 __do_sys_add_key security/keys/keyctl.c:124 [inline]
 __se_sys_add_key security/keys/keyctl.c:72 [inline]
 __x64_sys_add_key+0x1a2/0x380 security/keys/keyctl.c:72
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 18732 Comm: syz-executor.0 Not tainted 5.4.0-rc6+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 18732 Comm: syz-executor.0 Not tainted 5.4.0-rc6+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0xf5/0x159 lib/dump_stack.c:113
 panic+0x210/0x640 kernel/panic.c:221
 kcsan_report.cold+0xc/0xe kernel/kcsan/report.c:302
 kcsan_setup_watchpoint+0x3fe/0x410 kernel/kcsan/core.c:357
 check_access kernel/kcsan/core.c:409 [inline]
 __tsan_unaligned_write4+0x143/0x1f0 kernel/kcsan/core.c:529
 get_cred include/linux/cred.h:253 [inline]
 lookup_user_key+0xc6/0xb30 security/keys/process_keys.c:626
 __do_sys_add_key security/keys/keyctl.c:124 [inline]
 __se_sys_add_key security/keys/keyctl.c:72 [inline]
 __x64_sys_add_key+0x1a2/0x380 security/keys/keyctl.c:72
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45a219
Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fefb0536c78 EFLAGS: 00000246 ORIG_RAX: 00000000000000f8
RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 000000000045a219
RDX: 0000000020001000 RSI: 0000000020001000 RDI: 0000000020002000
RBP: 000000000075bf20 R08: fffffffffffffffc R09: 0000000000000000
R10: 0000000000000093 R11: 0000000000000246 R12: 00007fefb05376d4
R13: 00000000004c043d R14: 00000000004d2a88 R15: 00000000ffffffff
Kernel Offset: disabled
Rebooting in 86400 seconds..