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Subject[PATCH 5.15 179/196] ucounts: In set_cred_ucounts assume new->ucounts is non-NULL
Date
From: Eric W. Biederman <ebiederm@xmission.com>

commit 99c31f9feda41d0f10d030dc04ba106c93295aa2 upstream.

Any cred that is destined for use by commit_creds must have a non-NULL
cred->ucounts field. Only curing credential construction is a NULL
cred->ucounts valid. Only abort_creds, put_cred, and put_cred_rcu
needs to deal with a cred with a NULL ucount. As set_cred_ucounts is
non of those case don't confuse people by handling something that can
not happen.

Link: https://lkml.kernel.org/r/871r4irzds.fsf_-_@disp2133
Tested-by: Yu Zhao <yuzhao@google.com>
Reviewed-by: Alexey Gladkov <legion@kernel.org>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
kernel/cred.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)

--- a/kernel/cred.c
+++ b/kernel/cred.c
@@ -676,15 +676,14 @@ int set_cred_ucounts(struct cred *new)
* This optimization is needed because alloc_ucounts() uses locks
* for table lookups.
*/
- if (old_ucounts && old_ucounts->ns == new->user_ns && uid_eq(old_ucounts->uid, new->euid))
+ if (old_ucounts->ns == new->user_ns && uid_eq(old_ucounts->uid, new->euid))
return 0;

if (!(new_ucounts = alloc_ucounts(new->user_ns, new->euid)))
return -EAGAIN;

new->ucounts = new_ucounts;
- if (old_ucounts)
- put_ucounts(old_ucounts);
+ put_ucounts(old_ucounts);

return 0;
}

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