Commit 99c31f9f authored Oct 16, 2021 by Eric W. Biederman

ucounts: In set_cred_ucounts assume new->ucounts is non-NULL

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>

parent 5ebcbe34

kernel/cred.c

+2 −3

Original line number	Diff line number	Diff line
		@@ -676,14 +676,13 @@ 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);

		return 0;