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authorDavid Ahern <dsa@cumulusnetworks.com>2016-11-02 12:08:25 -0700
committerDavid S. Miller <davem@davemloft.net>2016-11-03 16:05:44 -0400
commitda96786e26c3ae47316db2b92046b11268c4379c (patch)
tree927e46eccc644ed5b0395194175da0eb226cce68
parentac9e70b17ecd7c6e933ff2eaf7ab37429e71bf4d (diff)
net: tcp: check skb is non-NULL for exact match on lookups
Andrey reported the following error report while running the syzkaller fuzzer: general protection fault: 0000 [#1] SMP KASAN Dumping ftrace buffer: (ftrace buffer empty) Modules linked in: CPU: 0 PID: 648 Comm: syz-executor Not tainted 4.9.0-rc3+ #333 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 task: ffff8800398c4480 task.stack: ffff88003b468000 RIP: 0010:[<ffffffff83091106>] [< inline >] inet_exact_dif_match include/net/tcp.h:808 RIP: 0010:[<ffffffff83091106>] [<ffffffff83091106>] __inet_lookup_listener+0xb6/0x500 net/ipv4/inet_hashtables.c:219 RSP: 0018:ffff88003b46f270 EFLAGS: 00010202 RAX: 0000000000000004 RBX: 0000000000004242 RCX: 0000000000000001 RDX: 0000000000000000 RSI: ffffc90000e3c000 RDI: 0000000000000054 RBP: ffff88003b46f2d8 R08: 0000000000004000 R09: ffffffff830910e7 R10: 0000000000000000 R11: 000000000000000a R12: ffffffff867fa0c0 R13: 0000000000004242 R14: 0000000000000003 R15: dffffc0000000000 FS: 00007fb135881700(0000) GS:ffff88003ec00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000020cc3000 CR3: 000000006d56a000 CR4: 00000000000006f0 Stack: 0000000000000000 000000000601a8c0 0000000000000000 ffffffff00004242 424200003b9083c2 ffff88003def4041 ffffffff84e7e040 0000000000000246 ffff88003a0911c0 0000000000000000 ffff88003a091298 ffff88003b9083ae Call Trace: [<ffffffff831100f4>] tcp_v4_send_reset+0x584/0x1700 net/ipv4/tcp_ipv4.c:643 [<ffffffff83115b1b>] tcp_v4_rcv+0x198b/0x2e50 net/ipv4/tcp_ipv4.c:1718 [<ffffffff83069d22>] ip_local_deliver_finish+0x332/0xad0 net/ipv4/ip_input.c:216 ... MD5 has a code path that calls __inet_lookup_listener with a null skb, so inet{6}_exact_dif_match needs to check skb against null before pulling the flag. Fixes: a04a480d4392 ("net: Require exact match for TCP socket lookups if dif is l3mdev") Reported-by: Andrey Konovalov <andreyknvl@google.com> Signed-off-by: David Ahern <dsa@cumulusnetworks.com> Tested-by: Andrey Konovalov <andreyknvl@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--include/linux/ipv6.h2
-rw-r--r--include/net/tcp.h2
2 files changed, 2 insertions, 2 deletions
diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
index ca1ad9ebbc92..a0649973ee5b 100644
--- a/include/linux/ipv6.h
+++ b/include/linux/ipv6.h
@@ -149,7 +149,7 @@ static inline bool inet6_exact_dif_match(struct net *net, struct sk_buff *skb)
{
#if defined(CONFIG_NET_L3_MASTER_DEV)
if (!net->ipv4.sysctl_tcp_l3mdev_accept &&
- ipv6_l3mdev_skb(IP6CB(skb)->flags))
+ skb && ipv6_l3mdev_skb(IP6CB(skb)->flags))
return true;
#endif
return false;
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 5b82d4d94834..304a8e17bc87 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -805,7 +805,7 @@ static inline bool inet_exact_dif_match(struct net *net, struct sk_buff *skb)
{
#if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
if (!net->ipv4.sysctl_tcp_l3mdev_accept &&
- ipv4_l3mdev_skb(TCP_SKB_CB(skb)->header.h4.flags))
+ skb && ipv4_l3mdev_skb(TCP_SKB_CB(skb)->header.h4.flags))
return true;
#endif
return false;