From: Chuck Ebbert <76306.1226@compuserve.com>
Date: Thu, 4 Jan 2007 07:59:56 +0000 (-0500)
Subject: [PATCH] ebtables: don't compute gap before checking struct type
X-Git-Tag: v2.6.19.2~10
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ff6173b1de40f8b0341c18a8e12414a59bcf7f52;p=thirdparty%2Fkernel%2Fstable.git

[PATCH] ebtables: don't compute gap before checking struct type

We cannot compute the gap until we know we have a 'struct ebt_entry'
and not 'struct ebt_entries'.  Failure to check can cause crash.

Tested-by: Santiago Garcia Mantinan <manty@manty.net>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: Chuck Ebbert <76306.1226@compuserve.com>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
---

diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c
index 136ed7d4bd732..473ca3ac6c867 100644
--- a/net/bridge/netfilter/ebtables.c
+++ b/net/bridge/netfilter/ebtables.c
@@ -575,7 +575,7 @@ ebt_check_entry(struct ebt_entry *e, struct ebt_table_info *newinfo,
 	struct ebt_entry_target *t;
 	struct ebt_target *target;
 	unsigned int i, j, hook = 0, hookmask = 0;
-	size_t gap = e->next_offset - e->target_offset;
+	size_t gap;
 	int ret;
 
 	/* don't mess with the struct ebt_entries */
@@ -625,6 +625,7 @@ ebt_check_entry(struct ebt_entry *e, struct ebt_table_info *newinfo,
 	if (ret != 0)
 		goto cleanup_watchers;
 	t = (struct ebt_entry_target *)(((char *)e) + e->target_offset);
+	gap = e->next_offset - e->target_offset;
 	target = find_target_lock(t->u.name, &ret, &ebt_mutex);
 	if (!target)
 		goto cleanup_watchers;