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From:   ebiederm@xmission.com (Eric W. Biederman)
To:     Alexey Gladkov <legion@kernel.org>
Cc:     Rune Kleveland <rune.kleveland@infomedia.dk>,
        Yu Zhao <yuzhao@google.com>,
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Date:   Mon, 18 Oct 2021 12:55:43 -0500
In-Reply-To: <877dearzfo.fsf_-_@disp2133> (Eric W. Biederman's message of
        "Mon, 18 Oct 2021 12:54:35 -0500")
Message-ID: <871r4irzds.fsf_-_@disp2133>
User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux)
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Content-Type: text/plain
Subject: [PATCH 1/4] ucounts: In set_cred_ucounts assume new->ucounts is non-NULL
Precedence: bulk


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.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 kernel/cred.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/kernel/cred.c b/kernel/cred.c
index 1ae0b4948a5a..473d17c431f3 100644
--- 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;
 }
-- 
2.20.1