[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+b69368fd933c6c592...@syzkaller.appspotmail.com
Signed-off-by: Myungho Jung <mhju...@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