From 9f7e43da6ae4862b48bac233838ba808c1167a0d Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Tue, 9 Oct 2018 09:59:36 -0700 Subject: [PATCH] net/xfrm: fix out-of-bounds packet access BUG: KASAN: slab-out-of-bounds in _decode_session6+0x1331/0x14e0 net/ipv6/xfrm6_policy.c:161 Read of size 1 at addr ffff8801d882eec7 by task syz-executor1/6667 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1c9/0x2b4 lib/dump_stack.c:113 print_address_description+0x6c/0x20b mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report.cold.7+0x242/0x30d mm/kasan/report.c:412 __asan_report_load1_noabort+0x14/0x20 mm/kasan/report.c:430 _decode_session6+0x1331/0x14e0 net/ipv6/xfrm6_policy.c:161 __xfrm_decode_session+0x71/0x140 net/xfrm/xfrm_policy.c:2299 xfrm_decode_session include/net/xfrm.h:1232 [inline] vti6_tnl_xmit+0x3c3/0x1bc1 net/ipv6/ip6_vti.c:542 __netdev_start_xmit include/linux/netdevice.h:4313 [inline] netdev_start_xmit include/linux/netdevice.h:4322 [inline] xmit_one net/core/dev.c:3217 [inline] dev_hard_start_xmit+0x272/0xc10 net/core/dev.c:3233 __dev_queue_xmit+0x2ab2/0x3870 net/core/dev.c:3803 dev_queue_xmit+0x17/0x20 net/core/dev.c:3836 Reported-by: syzbot+acffccec848dc13fe459@syzkaller.appspotmail.com Reported-by: Eric Dumazet Signed-off-by: Alexei Starovoitov Signed-off-by: Steffen Klassert --- net/ipv6/xfrm6_policy.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/ipv6/xfrm6_policy.c b/net/ipv6/xfrm6_policy.c index ef3defaf43b9..d35bcf92969c 100644 --- a/net/ipv6/xfrm6_policy.c +++ b/net/ipv6/xfrm6_policy.c @@ -146,8 +146,8 @@ _decode_session6(struct sk_buff *skb, struct flowi *fl, int reverse) fl6->daddr = reverse ? hdr->saddr : hdr->daddr; fl6->saddr = reverse ? hdr->daddr : hdr->saddr; - while (nh + offset + 1 < skb->data || - pskb_may_pull(skb, nh + offset + 1 - skb->data)) { + while (nh + offset + sizeof(*exthdr) < skb->data || + pskb_may_pull(skb, nh + offset + sizeof(*exthdr) - skb->data)) { nh = skb_network_header(skb); exthdr = (struct ipv6_opt_hdr *)(nh + offset);