* [PATCH] cred: mark the copy in prepare_creds() as a data race
@ 2026-10-30 3:33 Babanpreet Singh
2026-10-30 3:37 ` sashiko-bot
0 siblings, 1 reply; 2+ messages in thread
From: Babanpreet Singh @ 2026-10-30 3:33 UTC (permalink / raw)
To: Paul Moore
Cc: Serge Hallyn, linux-security-module, linux-kernel,
Babanpreet Singh, syzbot+ee58b040032d8bed63d9,
syzbot+557fdc985d6ac3831e14
prepare_creds() copies the old cred while other tasks may be changing
its refcount. Mark as data race.
Reported-by: syzbot+ee58b040032d8bed63d9@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=ee58b040032d8bed63d9
Reported-by: syzbot+557fdc985d6ac3831e14@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=557fdc985d6ac3831e14
Assisted-by: Claude:claude-opus-5-5
Signed-off-by: Babanpreet Singh <bbnpreetsingh@gmail.com>
---
Compile tested with gcc and clang; the KCSAN instrumentation of
kernel/cred.o was checked before and after.
kernel/cred.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/cred.c b/kernel/cred.c
index d01df40a9a386..d212db445c138 100644
--- a/kernel/cred.c
+++ b/kernel/cred.c
@@ -189,7 +189,7 @@ struct cred *prepare_creds(void)
kdebug("prepare_creds() alloc %p", new);
old = task->cred;
- memcpy(new, old, sizeof(struct cred));
+ data_race(memcpy(new, old, sizeof(struct cred)));
new->non_rcu = 0;
atomic_long_set(&new->usage, 1);
base-commit: 881f19c2ffbc73f351b257e09c71e6059939b770
--
2.43.0
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2026-10-30 3:33 [PATCH] cred: mark the copy in prepare_creds() as a data race Babanpreet Singh
2026-10-30 3:37 ` sashiko-bot
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