Re: [PATCH net v2 1/3] xfrm: Fix xfrm_input() to verify state is valid when (encap_type < 0)

[Steffen Klassert]

On Tue, Nov 28, 2017 at 07:55:40PM +0200, av...@mellanox.com wrote:
> From: Aviv Heller 
> 
> Code path when (encap_type < 0) does not verify the state is valid
> before progressing.
> 
> This will result in a crash if, for instance, x->km.state ==
> XFRM_STATE_ACQ.
> 
> Fixes: 7785bba299a8 ("esp: Add a software GRO codepath")
> Signed-off-by: Aviv Heller 
> Signed-off-by: Yevgeny Kliteynik 

Good catch!

Patch applied, thanks Aviv!

[PATCH net v2 1/3] xfrm: Fix xfrm_input() to verify state is valid when (encap_type < 0)

[avivh]

From: Aviv Heller 

Code path when (encap_type < 0) does not verify the state is valid
before progressing.

This will result in a crash if, for instance, x->km.state ==
XFRM_STATE_ACQ.

Fixes: 7785bba299a8 ("esp: Add a software GRO codepath")
Signed-off-by: Aviv Heller 
Signed-off-by: Yevgeny Kliteynik 
---
 net/xfrm/xfrm_input.c | 12 +++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/net/xfrm/xfrm_input.c b/net/xfrm/xfrm_input.c
index 347ab31..da64473 100644
--- a/net/xfrm/xfrm_input.c
+++ b/net/xfrm/xfrm_input.c
@@ -207,7 +207,7 @@ int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 
spi, int encap_type)
xfrm_address_t *daddr;
struct xfrm_mode *inner_mode;
u32 mark = skb->mark;
-   unsigned int family;
+   unsigned int family = AF_UNSPEC;
int decaps = 0;
int async = 0;
bool xfrm_gro = false;
@@ -216,6 +216,16 @@ int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 
spi, int encap_type)
 
if (encap_type < 0) {
x = xfrm_input_state(skb);
+
+   if (unlikely(x->km.state != XFRM_STATE_VALID)) {
+   if (x->km.state == XFRM_STATE_ACQ)
+   XFRM_INC_STATS(net, LINUX_MIB_XFRMACQUIREERROR);
+   else
+   XFRM_INC_STATS(net,
+  LINUX_MIB_XFRMINSTATEINVALID);
+   goto drop;
+   }
+
family = x->outer_mode->afinfo->family;
 
/* An encap_type of -1 indicates async resumption. */
-- 
1.8.3.1