[PATCH 09/18] netfilter: x_tables: check for size overflow

[Pablo Neira Ayuso]

From: Florian Westphal <f...@strlen.de>

Ben Hawkes says:
 integer overflow in xt_alloc_table_info, which on 32-bit systems can
 lead to small structure allocation and a copy_from_user based heap
 corruption.

Reported-by: Ben Hawkes <haw...@google.com>
Signed-off-by: Florian Westphal <f...@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pa...@netfilter.org>
---
 net/netfilter/x_tables.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c
index d0cd2b9..582c9cf 100644
--- a/net/netfilter/x_tables.c
+++ b/net/netfilter/x_tables.c
@@ -659,6 +659,9 @@ struct xt_table_info *xt_alloc_table_info(unsigned int size)
        struct xt_table_info *info = NULL;
        size_t sz = sizeof(*info) + size;
 
+       if (sz < sizeof(*info))
+               return NULL;
+
        /* Pedantry: prevent them from hitting BUG() in vmalloc.c --RR */
        if ((SMP_ALIGN(size) >> PAGE_SHIFT) + 2 > totalram_pages)
                return NULL;
-- 
2.1.4