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net/xfrm_input: fix possible NULL deref of tunnel.ip6->parms.i_key 

Running LTP 'icmp-uni-basic.sh -6 -p ipcomp -m tunnel' test over
openvswitch + veth can trigger kernel panic:

  BUG: unable to handle kernel NULL pointer dereference
  at 00000000000000e0 IP: [<ffffffff8169d1d2>] xfrm_input+0x82/0x750
  ...
  [<ffffffff816d472e>] xfrm6_rcv_spi+0x1e/0x20
  [<ffffffffa082c3c2>] xfrm6_tunnel_rcv+0x42/0x50 [xfrm6_tunnel]
  [<ffffffffa082727e>] tunnel6_rcv+0x3e/0x8c [tunnel6]
  [<ffffffff8169f365>] ip6_input_finish+0xd5/0x430
  [<ffffffff8169fc53>] ip6_input+0x33/0x90
  [<ffffffff8169f1d5>] ip6_rcv_finish+0xa5/0xb0
  ...

It seems that tunnel.ip6 can have garbage values and also dereferenced
without a proper check, only tunnel.ip4 is being verified. Fix it by
adding one more if block for AF_INET6 and initialize tunnel.ip6 with NULL
inside xfrm6_rcv_spi() (which is similar to xfrm4_rcv_spi()).

Fixes: 049f8e2 ("xfrm: Override skb->mark with tunnel->parm.i_key in xfrm_input")

Signed-off-by: Alexey Kodanev <alexey.kodanev@oracle.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
This commit is contained in:
Alexey Kodanev 2016-08-10 13:54:57 +03:00 committed by Steffen Klassert
parent 6916fb3b10
commit 1625f45299
2 changed files with 8 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
net/ipv6/xfrm6_input.c
View File

@ -23,6 +23,7 @@ int xfrm6_extract_input(struct xfrm_state *x, struct sk_buff *skb)
int xfrm6_rcv_spi(struct sk_buff *skb, int nexthdr, __be32 spi)
{
XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip6 = NULL;
XFRM_SPI_SKB_CB(skb)->family = AF_INET6;
XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct ipv6hdr, daddr);
return xfrm_input(skb, nexthdr, spi, 0);

14
net/xfrm/xfrm_input.c
View File

@ -207,15 +207,15 @@ int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type)
family = XFRM_SPI_SKB_CB(skb)->family;
/* if tunnel is present override skb->mark value with tunnel i_key */
if (XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip4) {
switch (family) {
case AF_INET:
switch (family) {
case AF_INET:
if (XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip4)
mark = be32_to_cpu(XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip4->parms.i_key);
break;
case AF_INET6:
break;
case AF_INET6:
if (XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip6)
mark = be32_to_cpu(XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip6->parms.i_key);
break;
}
break;
}
/* Allocate new secpath or COW existing one. */