| From | Greg Kroah-Hartman <> | Subject | [PATCH 5.15 179/196] ucounts: In set_cred_ucounts assume new->ucounts is non-NULL | Date | Mon, 21 Feb 2022 09:50:11 +0100 |
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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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