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

From: Chuck Ebbert
Date: Tue Dec 26 2006 - 13:00:40 EST

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@xxxxxxxxx>

Signed-off-by: Chuck Ebbert <76306.1226@xxxxxxxxxxxxxx>
Can we get this upstream quickly? The bug's also in and

--- 2.6.20-rc1-32smp.orig/net/bridge/netfilter/ebtables.c
+++ 2.6.20-rc1-32smp/net/bridge/netfilter/ebtables.c
@@ -610,7 +610,7 @@ ebt_check_entry(struct ebt_entry *e, str
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 */
@@ -660,6 +660,7 @@ ebt_check_entry(struct ebt_entry *e, str
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;
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/