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SubjectRe: [PATCH v2] xfrm: Reset secpath in xfrm failure
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On 03/06/2019 01:55 PM, 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.
>
> Fixes: 7785bba299a8 ("esp: Add a software GRO codepath")
> Reported-by: syzbot+b69368fd933c6c592f4c@syzkaller.appspotmail.com
> Signed-off-by: Myungho Jung <mhjungk@gmail.com>
> ---
> Changes in v2:
> - Add fixes tag.
>
> 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;
> + }
>

I suggest another exit label, so that you replace "goto out" by "goto out_reset";

diff --git a/net/ipv4/esp4_offload.c b/net/ipv4/esp4_offload.c
index 8756e0e790d2a94a5b4a587c3bc3de0673baf2c4..76f754f6692696ba2aa8c9eb03b68b92d1e39ee1 100644
--- a/net/ipv4/esp4_offload.c
+++ b/net/ipv4/esp4_offload.c
@@ -82,6 +82,8 @@ static struct sk_buff *esp4_gro_receive(struct list_head *head,
xfrm_input(skb, IPPROTO_ESP, spi, -2);

return ERR_PTR(-EINPROGRESS);
+out_reset:
+ secpath_reset(skb);
out:
skb_push(skb, offset);
NAPI_GRO_CB(skb)->same_flow = 0;



> 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;
> }
> }


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