+ unshare-fix-nsproxy-leak-in-ksys_unshare-on-set_cred_ucounts-failure.patch added to mm-nonmm-unstable branch

+ unshare-fix-nsproxy-leak-in-ksys_unshare-on-set_cred_ucounts-failure.patch added to mm-nonmm-unstable branch

[Andrew Morton]

The patch titled
     Subject: unshare: fix nsproxy leak in ksys_unshare() on set_cred_ucounts() failure
has been added to the -mm mm-nonmm-unstable branch.  Its filename is
     unshare-fix-nsproxy-leak-in-ksys_unshare-on-set_cred_ucounts-failure.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/unshare-fix-nsproxy-leak-in-ksys_unshare-on-set_cred_ucounts-failure.patch

This patch will later appear in the mm-nonmm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Michal Grzedzicki <mge@meta.com>
Subject: unshare: fix nsproxy leak in ksys_unshare() on set_cred_ucounts() failure
Date: Fri, 13 Feb 2026 11:39:59 -0800

When set_cred_ucounts() fails in ksys_unshare() new_nsproxy is leaked.

Let's call put_nsproxy() if that happens.

Link: https://lkml.kernel.org/r/20260213193959.2556730-1-mge@meta.com
Fixes: 905ae01c4ae2 ("Add a reference to ucounts for each cred")
Signed-off-by: Michal Grzedzicki <mge@meta.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexey Gladkov (Intel) <legion@kernel.org>
Cc: Ben Segall <bsegall@google.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Kees Cook <kees@kernel.org>
Cc: "Liam R. Howlett" <Liam.Howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 kernel/fork.c |   11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

--- a/kernel/fork.c~unshare-fix-nsproxy-leak-in-ksys_unshare-on-set_cred_ucounts-failure
+++ a/kernel/fork.c
@@ -3179,11 +3179,10 @@ int ksys_unshare(unsigned long unshare_f
 					 new_cred, new_fs);
 	if (err)
 		goto bad_unshare_cleanup_cred;
-
 	if (new_cred) {
 		err = set_cred_ucounts(new_cred);
 		if (err)
-			goto bad_unshare_cleanup_cred;
+			goto bad_unshare_cleanup_nsproxy;
 	}
 
 	if (new_fs || new_fd || do_sysvsem || new_cred || new_nsproxy) {
@@ -3199,8 +3198,10 @@ int ksys_unshare(unsigned long unshare_f
 			shm_init_task(current);
 		}
 
-		if (new_nsproxy)
+		if (new_nsproxy) {
 			switch_task_namespaces(current, new_nsproxy);
+			new_nsproxy = NULL;
+		}
 
 		task_lock(current);
 
@@ -3229,13 +3230,15 @@ int ksys_unshare(unsigned long unshare_f
 
 	perf_event_namespaces(current);
 
+bad_unshare_cleanup_nsproxy:
+	if (new_nsproxy)
+		put_nsproxy(new_nsproxy);
 bad_unshare_cleanup_cred:
 	if (new_cred)
 		put_cred(new_cred);
 bad_unshare_cleanup_fd:
 	if (new_fd)
 		put_files_struct(new_fd);
-
 bad_unshare_cleanup_fs:
 	if (new_fs)
 		free_fs_struct(new_fs);
_

Patches currently in -mm which might be from mge@meta.com are

unshare-fix-nsproxy-leak-in-ksys_unshare-on-set_cred_ucounts-failure.patch