netfilter: x_tables: limit allocation requests for blob rule heads
This is a very conservative limit (134217728 rules), but good
enough to not trigger frequent oom from syzkaller.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c
index dc68ac496..01f8e12 100644
--- a/net/netfilter/x_tables.c
+++ b/net/netfilter/x_tables.c
@@ -894,6 +894,9 @@ EXPORT_SYMBOL(xt_check_entry_offsets);
*/
unsigned int *xt_alloc_entry_offsets(unsigned int size)
{
+ if (size > XT_MAX_TABLE_SIZE / sizeof(unsigned int))
+ return NULL;
+
return kvmalloc_array(size, sizeof(unsigned int), GFP_KERNEL | __GFP_ZERO);
}
