lkml.org 
[lkml]   [2010]   [Apr]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] CRED: Fix double free in prepare_usermodehelper_creds() error handling
* David Howells (dhowells@redhat.com) wrote:
> Patch 570b8fb505896e007fd3bb07573ba6640e51851d:
>
> Author: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
> Date: Tue Mar 30 00:04:00 2010 +0100
> Subject: CRED: Fix memory leak in error handling
>
> attempts to fix a memory leak in the error handling by making the offending
> return statement into a jump down to the bottom of the function where a
> kfree(tgcred) is inserted.
>
> This is, however, incorrect, as it does a kfree() after doing put_cred() if
> security_prepare_creds() fails. That will result in a double free if 'error'
> is jumped to as put_cred() will also attempt to free the new tgcred record by
> virtue of it being pointed to by the new cred record.

OK, I missed the fact taht put_cred() performs the kfree. Thanks for the fix.

Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

>
> Signed-off-by: David Howells <dhowells@redhat.com>
> ---
>
> kernel/cred.c | 2 ++
> 1 files changed, 2 insertions(+), 0 deletions(-)
>
> diff --git a/kernel/cred.c b/kernel/cred.c
> index e1dbe9e..ce1a52b 100644
> --- a/kernel/cred.c
> +++ b/kernel/cred.c
> @@ -398,6 +398,8 @@ struct cred *prepare_usermodehelper_creds(void)
>
> error:
> put_cred(new);
> + return NULL;
> +
> free_tgcred:
> #ifdef CONFIG_KEYS
> kfree(tgcred);
>

--
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com


\
 
 \ /
  Last update: 2010-04-21 15:49    [from the cache]
©2003-2014 Jasper Spaans. Advertise on this site