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FAILED: patch "[PATCH] ucounts: Proper error handling in set_cred_ucounts" failed to apply to 5.10-stable tree

PATCH [email protected] 1 participant 1 message Oct 24, 2021

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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 <[email protected]>.

thanks,

greg k-h

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

From 34dc2fd6e6908499b669c7b45320cddf38b332e1 Mon Sep 17 00:00:00 2001
From: "Eric W. Biederman" <[email protected]>
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 [email protected]
Fixes 905ae01c4ae2 ("Add a reference to ucounts for each cred")
Link https://lkml.kernel.org/r/87pms2s0v8.fsf_-_@disp2133 open here
Tested-by Yu Zhao <[email protected]>
Reviewed-by Alexey Gladkov <[email protected]>
Signed-off-by "Eric W. Biederman" <[email protected]>
kernel/cred.c +3 -2
index 3d163bfd64a9..16c05dfbec4d 100644
@@ -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);