lkml.org 
[lkml]   [2020]   [Jun]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH] selinux: fix another double free
Hi Tom,

On Thu, Jun 11, 2020 at 5:58 PM <trix@redhat.com> wrote:
> From: Tom Rix <trix@redhat.com>
>
> Clang static analysis reports this double free error
>
> security/selinux/ss/conditional.c:139:2: warning: Attempt to free released memory [unix.Malloc]
> kfree(node->expr.nodes);
> ^~~~~~~~~~~~~~~~~~~~~~~
>
> When cond_read_node fails, it calls cond_node_destroy which frees the
> node but does not poison the entry in the node list. So when it
> returns to its caller cond_read_list, cond_read_list deletes the
> partial list. The latest entry in the list will be deleted twice.
>
> So instead of freeing the node in cond_read_node, let list freeing in
> code_read_list handle the freeing the problem node along with all of the the

There is an extra "the" before "freeing".

> earlier nodes.
>
> Signed-off-by: Tom Rix <trix@redhat.com>
> ---
> security/selinux/ss/conditional.c | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/security/selinux/ss/conditional.c b/security/selinux/ss/conditional.c
> index da94a1b4bfda..ffb31af22f4f 100644
> --- a/security/selinux/ss/conditional.c
> +++ b/security/selinux/ss/conditional.c
> @@ -411,7 +411,6 @@ static int cond_read_node(struct policydb *p, struct cond_node *node, void *fp)
> goto err;
> return 0;
> err:
> - cond_node_destroy(node);
> return rc;

Since there is now just "return rc" in the error path, can you please
replace all the gotos with plain return statements? And please also
add a Fixes: tag pointing to the commit that introduced the bug (see
Stephen's reply).

Thanks,

--
Ondrej Mosnacek
Software Engineer, Platform Security - SELinux kernel
Red Hat, Inc.

\
 
 \ /
  Last update: 2020-06-11 19:14    [W:0.028 / U:0.144 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site