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Commit 1625f452 authored by Alexey Kodanev's avatar Alexey Kodanev Committed by Steffen Klassert
Browse files

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: 049f8e2e ("xfrm: Override skb->mark with tunnel->parm.i_key in xfrm_input")

Signed-off-by: default avatarAlexey Kodanev <alexey.kodanev@oracle.com>
Signed-off-by: default avatarSteffen Klassert <steffen.klassert@secunet.com>
parent 6916fb3b

net/ipv6/xfrm6_input.c

+1 −0
Original line number Original line Diff line number Diff line
@@ -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)

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)->family = AF_INET6;

	XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct ipv6hdr, daddr);

	XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct ipv6hdr, daddr);

	return xfrm_input(skb, nexthdr, spi, 0);

	return xfrm_input(skb, nexthdr, spi, 0);

net/xfrm/xfrm_input.c

+7 −7
Original line number Original line Diff line number Diff line
@@ -207,16 +207,16 @@ int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type) 
	family = XFRM_SPI_SKB_CB(skb)->family;

	family = XFRM_SPI_SKB_CB(skb)->family;





	/* if tunnel is present override skb->mark value with tunnel i_key */

	/* if tunnel is present override skb->mark value with tunnel i_key */

	if (XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip4) {

	switch (family) {

	switch (family) {

	case AF_INET:

	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);

			mark = be32_to_cpu(XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip4->parms.i_key);

		break;

		break;

	case AF_INET6:

	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);

			mark = be32_to_cpu(XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip6->parms.i_key);

		break;

		break;

	}

	}

	}





	/* Allocate new secpath or COW existing one. */

	/* Allocate new secpath or COW existing one. */

	if (!skb->sp || atomic_read(&skb->sp->refcnt) != 1) {

	if (!skb->sp || atomic_read(&skb->sp->refcnt) != 1) {