The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 34dc2fd6e6908499b669c7b45320cddf38b332e1 Mon Sep 17 00:00:00 2001

From: "Eric W. Biederman" ebiederm@xmission.com Date: Sat, 16 Oct 2021 12:47:51 -0500 Subject: [PATCH] ucounts: Proper error handling in set_cred_ucounts

Instead of leaking the ucounts in new if alloc_ucounts fails, store the result of alloc_ucounts into a temporary variable, which is later assigned to new->ucounts.

Cc: stable@vger.kernel.org Fixes: 905ae01c4ae2 ("Add a reference to ucounts for each cred") Link: https://lkml.kernel.org/r/87pms2s0v8.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

diff --git a/kernel/cred.c b/kernel/cred.c index 3d163bfd64a9..16c05dfbec4d 100644 --- a/kernel/cred.c +++ b/kernel/cred.c @@ -669,7 +669,7 @@ int set_cred_ucounts(struct cred *new) { struct task_struct *task = current; const struct cred *old = task->real_cred; - struct ucounts *old_ucounts = new->ucounts; + struct ucounts *new_ucounts, *old_ucounts = new->ucounts;

if (new->user == old->user && new->user_ns == old->user_ns) return 0; @@ -681,9 +681,10 @@ int set_cred_ucounts(struct cred *new) if (old_ucounts && 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))) + if (!(new_ucounts = alloc_ucounts(new->user_ns, new->euid))) return -EAGAIN;

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