[moderation] [keyrings?] [lsm?] KCSAN: data-race in search_nested_keyrings / search_nested_keyrings (4)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: e1afacb68573 Merge tag 'ceph-for-6.18-rc8' of https://gith..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15db1f42580000
kernel config: https://syzkaller.appspot.com/x/.config?x=655255e3ef31c19b
dashboard link: https://syzkaller.appspot.com/bug?extid=fba113b7915d88a69ecb
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
CC: [dhow...@redhat.com jar...@kernel.org jmo...@namei.org keyr...@vger.kernel.org linux-...@vger.kernel.org linux-secu...@vger.kernel.org pa...@paul-moore.com se...@hallyn.com]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a332549ce238/disk-e1afacb6.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/cdd20c605059/vmlinux-e1afacb6.xz
kernel image: https://storage.googleapis.com/syzbot-assets/af0a9cbc5e03/bzImage-e1afacb6.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+fba113...@syzkaller.appspotmail.com

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

write to 0xffff888101620c60 of 8 bytes by task 27180 on cpu 0:
search_nested_keyrings+0x79a/0x9b0 security/keys/keyring.c:859
keyring_search_rcu+0xf7/0x190 security/keys/keyring.c:925
get_user_session_keyring_rcu security/keys/process_keys.c:208 [inline]
search_cred_keyrings_rcu+0x2a3/0x3c0 security/keys/process_keys.c:500
search_process_keyrings_rcu+0x1e/0x190 security/keys/process_keys.c:544
request_key_and_link+0x14d/0xd70 security/keys/request_key.c:618
__do_sys_request_key security/keys/keyctl.c:222 [inline]
__se_sys_request_key+0x1df/0x290 security/keys/keyctl.c:167
__x64_sys_request_key+0x55/0x70 security/keys/keyctl.c:167
x64_sys_call+0x1d98/0x3000 arch/x86/include/generated/asm/syscalls_64.h:250
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

write to 0xffff888101620c60 of 8 bytes by task 27179 on cpu 1:
search_nested_keyrings+0x79a/0x9b0 security/keys/keyring.c:859
keyring_search_rcu+0xf7/0x190 security/keys/keyring.c:925
get_user_session_keyring_rcu security/keys/process_keys.c:208 [inline]
search_cred_keyrings_rcu+0x2a3/0x3c0 security/keys/process_keys.c:500
search_process_keyrings_rcu+0x1e/0x190 security/keys/process_keys.c:544
request_key_and_link+0x14d/0xd70 security/keys/request_key.c:618
__do_sys_request_key security/keys/keyctl.c:222 [inline]
__se_sys_request_key+0x1df/0x290 security/keys/keyctl.c:167
__x64_sys_request_key+0x55/0x70 security/keys/keyctl.c:167
x64_sys_call+0x1d98/0x3000 arch/x86/include/generated/asm/syscalls_64.h:250
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: 0x0000000077359e8e -> 0x0000000077359e90

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 27179 Comm: syz.4.8216 Tainted: G W syzkaller #0 PREEMPT(voluntary)
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
==================================================================


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