linux-kernel - Re: [PATCH] unshare: Fix nsproxy leak on set_cred

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Message-ID: <aRxKzrX5np4YpS19@example.org>
Date: Tue, 18 Nov 2025 11:30:38 +0100
From: Alexey Gladkov <legion@...nel.org>
To: Pavel Tikhomirov <ptikhomirov@...tuozzo.com>
Cc: Ingo Molnar <mingo@...hat.com>, Peter Zijlstra <peterz@...radead.org>,
	Juri Lelli <juri.lelli@...hat.com>,
	Vincent Guittot <vincent.guittot@...aro.org>,
	Dietmar Eggemann <dietmar.eggemann@....com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>,
	Valentin Schneider <vschneid@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	David Hildenbrand <david@...nel.org>,
	Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
	"Liam R. Howlett" <Liam.Howlett@...cle.com>,
	Vlastimil Babka <vbabka@...e.cz>, Mike Rapoport <rppt@...nel.org>,
	Suren Baghdasaryan <surenb@...gle.com>,
	Michal Hocko <mhocko@...e.com>, Kees Cook <kees@...nel.org>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	stable@...r.kernel.org
Subject: Re: [PATCH] unshare: Fix nsproxy leak on set_cred_ucounts() error
 path

On Tue, Nov 18, 2025 at 02:45:50PM +0800, Pavel Tikhomirov wrote:
> If unshare_nsproxy_namespaces() successfully creates the new_nsproxy,
> but then set_cred_ucounts() fails, on its error path there is no cleanup
> for new_nsproxy, so it is leaked. Let's fix that by freeing new_nsproxy
> if it's not NULL on this error path.
> 
> Fixes: 905ae01c4ae2a ("Add a reference to ucounts for each cred")
> Signed-off-by: Pavel Tikhomirov <ptikhomirov@...tuozzo.com>

Cc: stable@...r.kernel.org 
Acked-by: Alexey Gladkov <legion@...nel.org>

> ---
>  kernel/fork.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/fork.c b/kernel/fork.c
> index 3da0f08615a95..6f7332e3e0c8c 100644
> --- a/kernel/fork.c
> +++ b/kernel/fork.c
> @@ -3133,8 +3133,11 @@ int ksys_unshare(unsigned long unshare_flags)
>  
>  	if (new_cred) {
>  		err = set_cred_ucounts(new_cred);
> -		if (err)
> +		if (err) {
> +			if (new_nsproxy)
> +				free_nsproxy(new_nsproxy);
>  			goto bad_unshare_cleanup_cred;
> +		}
>  	}
>  
>  	if (new_fs || new_fd || do_sysvsem || new_cred || new_nsproxy) {
> -- 
> 2.51.1
> 

-- 
Rgrds, legion