[PATCH] xfrm: Reset secpath in xfrm failure

[PATCH] xfrm: Reset secpath in xfrm failure

[Myungho Jung]

In esp4_gro_receive() and esp6_gro_receive(), secpath can be allocated
without adding xfrm state to xvec. Then, sp->xvec[sp->len - 1] would
fail and result in dereferencing invalid pointer in esp4_gso_segment()
and esp6_gso_segment(). Reset secpath if xfrm function returns error.

Reported-by: syzbot+b69368fd933c6c592f4c@syzkaller.appspotmail.com
Signed-off-by: Myungho Jung <mhjungk@gmail.com>
---
 net/ipv4/esp4_offload.c | 9 +++++++--
 net/ipv6/esp6_offload.c | 9 +++++++--
 2 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/net/ipv4/esp4_offload.c b/net/ipv4/esp4_offload.c
index 8756e0e790d2..7329e40c73f6 100644
--- a/net/ipv4/esp4_offload.c
+++ b/net/ipv4/esp4_offload.c
@@ -51,14 +51,18 @@ static struct sk_buff *esp4_gro_receive(struct list_head *head,
 		if (!sp)
 			goto out;
 
-		if (sp->len == XFRM_MAX_DEPTH)
+		if (sp->len == XFRM_MAX_DEPTH) {
+			secpath_reset(skb);
 			goto out;
+		}
 
 		x = xfrm_state_lookup(dev_net(skb->dev), skb->mark,
 				      (xfrm_address_t *)&ip_hdr(skb)->daddr,
 				      spi, IPPROTO_ESP, AF_INET);
-		if (!x)
+		if (!x) {
+			secpath_reset(skb);
 			goto out;
+		}
 
 		sp->xvec[sp->len++] = x;
 		sp->olen++;
@@ -66,6 +70,7 @@ static struct sk_buff *esp4_gro_receive(struct list_head *head,
 		xo = xfrm_offload(skb);
 		if (!xo) {
 			xfrm_state_put(x);
+			secpath_reset(skb);
 			goto out;
 		}
 	}
diff --git a/net/ipv6/esp6_offload.c b/net/ipv6/esp6_offload.c
index d46b4eb645c2..399c688d192e 100644
--- a/net/ipv6/esp6_offload.c
+++ b/net/ipv6/esp6_offload.c
@@ -73,14 +73,18 @@ static struct sk_buff *esp6_gro_receive(struct list_head *head,
 		if (!sp)
 			goto out;
 
-		if (sp->len == XFRM_MAX_DEPTH)
+		if (sp->len == XFRM_MAX_DEPTH) {
+			secpath_reset(skb);
 			goto out;
+		}
 
 		x = xfrm_state_lookup(dev_net(skb->dev), skb->mark,
 				      (xfrm_address_t *)&ipv6_hdr(skb)->daddr,
 				      spi, IPPROTO_ESP, AF_INET6);
-		if (!x)
+		if (!x) {
+			secpath_reset(skb);
 			goto out;
+		}
 
 		sp->xvec[sp->len++] = x;
 		sp->olen++;
@@ -88,6 +92,7 @@ static struct sk_buff *esp6_gro_receive(struct list_head *head,
 		xo = xfrm_offload(skb);
 		if (!xo) {
 			xfrm_state_put(x);
+			secpath_reset(skb);
 			goto out;
 		}
 	}
-- 
2.17.1

Re: [PATCH] xfrm: Reset secpath in xfrm failure

[Steffen Klassert]

On Wed, Mar 06, 2019 at 04:33:08PM +0900, Myungho Jung wrote:
> In esp4_gro_receive() and esp6_gro_receive(), secpath can be allocated
> without adding xfrm state to xvec. Then, sp->xvec[sp->len - 1] would
> fail and result in dereferencing invalid pointer in esp4_gso_segment()
> and esp6_gso_segment(). Reset secpath if xfrm function returns error.
> 
> Reported-by: syzbot+b69368fd933c6c592f4c@syzkaller.appspotmail.com
> Signed-off-by: Myungho Jung <mhjungk@gmail.com>

The patch itself looks ok, but please add a 'Fixes' tag to
the commit message.

Thanks!

Re: [PATCH] xfrm: Reset secpath in xfrm failure

[Myungho Jung]

On Wed, Mar 06, 2019 at 12:35:43PM +0100, Steffen Klassert wrote:
> On Wed, Mar 06, 2019 at 04:33:08PM +0900, Myungho Jung wrote:
> > In esp4_gro_receive() and esp6_gro_receive(), secpath can be allocated
> > without adding xfrm state to xvec. Then, sp->xvec[sp->len - 1] would
> > fail and result in dereferencing invalid pointer in esp4_gso_segment()
> > and esp6_gso_segment(). Reset secpath if xfrm function returns error.
> > 
> > Reported-by: syzbot+b69368fd933c6c592f4c@syzkaller.appspotmail.com
> > Signed-off-by: Myungho Jung <mhjungk@gmail.com>
> 
> The patch itself looks ok, but please add a 'Fixes' tag to
> the commit message.
> 
> Thanks!

Hi Steffen,

Thanks for reviewing the change. I'll add fixes tag and resubmit it.

Thanks,
Myungho