netfilter 60/62: ebtables: abort if next_offset is too small

Patrick McHardy
2010-02-16T14:56:41Z

commit 1756de262e41112a8a8927808eb2f03d21fd4786
Author: Florian Westphal <fwestphal@astaro.com>
Date: Mon Feb 15 18:15:55 2010 +0100

netfilter: ebtables: abort if next_offset is too small

next_offset must be > 0, otherwise this loops forever.
The offset also contains the size of the ebt_entry structure
itself, so anything smaller is invalid.

Signed-off-by: Florian Westphal <fwestphal@astaro.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>

diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c
index bcdf02d..4370e96 100644
--- a/net/bridge/netfilter/ebtables.c
+++ b/net/bridge/netfilter/ebtables.c
@@ -444,6 +444,8 @@ static int ebt_verify_pointers(const struct ebt_replace *repl,
break;
if (left < e->next_offset)
break;
+ if (e->next_offset < sizeof(struct ebt_entry))
+ return -EINVAL;
offset += e->next_offset;
}
}