[PATCH] selinux: set next pointer before attaching to list

[PATCH] selinux: set next pointer before attaching to list

[Christian Göttsche]

Set the next pointer in filename_trans_read_helper() before attaching
the new node under construction to the list, otherwise garbage would be
dereferenced on subsequent failure during cleanup in the out goto label.

Fixes: 430059024389 ("selinux: implement new format of filename transitions")
Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
---
 security/selinux/ss/policydb.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/security/selinux/ss/policydb.c b/security/selinux/ss/policydb.c
index 28bd75dc6f71..2d528f699a22 100644
--- a/security/selinux/ss/policydb.c
+++ b/security/selinux/ss/policydb.c
@@ -2009,6 +2009,7 @@ static int filename_trans_read_helper(struct policydb *p, void *fp)
 		if (!datum)
 			goto out;
 
+		datum->next = NULL;
 		*dst = datum;
 
 		/* ebitmap_read() will at least init the bitmap */
@@ -2021,7 +2022,6 @@ static int filename_trans_read_helper(struct policydb *p, void *fp)
 			goto out;
 
 		datum->otype = le32_to_cpu(buf[0]);
-		datum->next = NULL;
 
 		dst = &datum->next;
 	}
-- 
2.40.1

Re: [PATCH] selinux: set next pointer before attaching to list

[Paul Moore]

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On Aug 18, 2023 =?UTF-8?q?Christian=20G=C3=B6ttsche?= <cgzones@googlemail.com> wrote:
> 
> Set the next pointer in filename_trans_read_helper() before attaching
> the new node under construction to the list, otherwise garbage would be
> dereferenced on subsequent failure during cleanup in the out goto label.
> 
> Fixes: 430059024389 ("selinux: implement new format of filename transitions")
> Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
> ---
>  security/selinux/ss/policydb.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Thanks Christian, nice catch!

I'm going to merge this into selinux/stable-6.5 with a stable tag, and
assuming all goes well with the automated testing I'll send this up to
Linus early next week.

--
paul-moore.com