From 889c604fd0b5f6d3b8694ade229ee44124de1127 Mon Sep 17 00:00:00 2001 From: Dmitry Vyukov Date: Thu, 28 Dec 2017 09:48:54 +0100 Subject: [PATCH] netfilter: x_tables: fix int overflow in xt_alloc_table_info() syzkaller triggered OOM kills by passing ipt_replace.size = -1 to IPT_SO_SET_REPLACE. The root cause is that SMP_ALIGN() in xt_alloc_table_info() causes int overflow and the size check passes when it should not. SMP_ALIGN() is no longer needed leftover. Remove SMP_ALIGN() call in xt_alloc_table_info(). Reported-by: syzbot+4396883fa8c4f64e0175@syzkaller.appspotmail.com Signed-off-by: Dmitry Vyukov Signed-off-by: Pablo Neira Ayuso --- net/netfilter/x_tables.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c index 55802e97f906..e02a21549c99 100644 --- a/net/netfilter/x_tables.c +++ b/net/netfilter/x_tables.c @@ -39,7 +39,6 @@ MODULE_LICENSE("GPL"); MODULE_AUTHOR("Harald Welte "); MODULE_DESCRIPTION("{ip,ip6,arp,eb}_tables backend module"); -#define SMP_ALIGN(x) (((x) + SMP_CACHE_BYTES-1) & ~(SMP_CACHE_BYTES-1)) #define XT_PCPU_BLOCK_SIZE 4096 struct compat_delta { @@ -1000,7 +999,7 @@ struct xt_table_info *xt_alloc_table_info(unsigned int size) return NULL; /* Pedantry: prevent them from hitting BUG() in vmalloc.c --RR */ - if ((SMP_ALIGN(size) >> PAGE_SHIFT) + 2 > totalram_pages) + if ((size >> PAGE_SHIFT) + 2 > totalram_pages) return NULL; info = kvmalloc(sz, GFP_KERNEL); -- 2.11.0