| Message ID | 20240222040046.2568269-1-lizhi.xu@windriver.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net-next] net/mpls: fix WARNING in mpls_gso_segment | expand |
On Thu, Feb 22, 2024 at 5:00 AM Lizhi Xu <lizhi.xu@windriver.com> wrote: > > When the network header pointer is greater than the inner network header, the > difference between the two can cause mpls_hlen overflow. > > Reported-and-tested-by: syzbot+99d15fcdb0132a1e1a82@syzkaller.appspotmail.com > Signed-off-by: Lizhi Xu <lizhi.xu@windriver.com> > --- > net/mpls/mpls_gso.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/net/mpls/mpls_gso.c b/net/mpls/mpls_gso.c > index 533d082f0701..2ab24b2fd90f 100644 > --- a/net/mpls/mpls_gso.c > +++ b/net/mpls/mpls_gso.c > @@ -25,11 +25,11 @@ static struct sk_buff *mpls_gso_segment(struct sk_buff *skb, > netdev_features_t mpls_features; > u16 mac_len = skb->mac_len; > __be16 mpls_protocol; > - unsigned int mpls_hlen; > + int mpls_hlen; > > skb_reset_network_header(skb); > mpls_hlen = skb_inner_network_header(skb) - skb_network_header(skb); > - if (unlikely(!mpls_hlen || mpls_hlen % MPLS_HLEN)) > + if (unlikely(mpls_hlen <= 0 || mpls_hlen % MPLS_HLEN)) > goto out; > if (unlikely(!pskb_may_pull(skb, mpls_hlen))) > goto out; > -- > 2.43.0 > I think Florian posted this patch, right ? We must add a Fixes: tag Also we should ask ourselves : Why are we even looking at skb_inner_network_header(skb) if this was not set ? Lets not hide a real bug, we need to understand the root cause.
On Thu, 22 Feb 2024 09:11:14 +0100, Eric Dumazet <edumazet@google.com> wrote: > > When the network header pointer is greater than the inner network header, the > > difference between the two can cause mpls_hlen overflow. > > > > Reported-and-tested-by: syzbot+99d15fcdb0132a1e1a82@syzkaller.appspotmail.com > > Signed-off-by: Lizhi Xu <lizhi.xu@windriver.com> > > --- > > net/mpls/mpls_gso.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/net/mpls/mpls_gso.c b/net/mpls/mpls_gso.c > > index 533d082f0701..2ab24b2fd90f 100644 > > --- a/net/mpls/mpls_gso.c > > +++ b/net/mpls/mpls_gso.c > > @@ -25,11 +25,11 @@ static struct sk_buff *mpls_gso_segment(struct sk_buff *skb, > > netdev_features_t mpls_features; > > u16 mac_len = skb->mac_len; > > __be16 mpls_protocol; > > - unsigned int mpls_hlen; > > + int mpls_hlen; > > > > skb_reset_network_header(skb); > > mpls_hlen = skb_inner_network_header(skb) - skb_network_header(skb); > > - if (unlikely(!mpls_hlen || mpls_hlen % MPLS_HLEN)) > > + if (unlikely(mpls_hlen <= 0 || mpls_hlen % MPLS_HLEN)) > > goto out; > > if (unlikely(!pskb_may_pull(skb, mpls_hlen))) > > goto out; > > -- > > 2.43.0 > > > > I think Florian posted this patch, right ? After you mentioned it, I discovered it. I forgot to check the email details before sending the patch. > > We must add a Fixes: tag > > Also we should ask ourselves : > Why are we even looking at skb_inner_network_header(skb) if this was not set ? __sys_sendto()-> __sock_sendmsg()-> netlink_sendmsg()-> netlink_broadcast_filtered()-> netlink_trim()-> 1323 pskb_expand_head(skb, 0, -delta, 1 (allocation & ~__GFP_DIRECT_RECLAIM) | 2 __GFP_NOWARN | __GFP_NORETRY); pskb_expand_head()-> skb_headers_offset_update()-> 1977 skb->inner_network_header += off; The root cause is: Initialize inner_network_header to 0 in network_trim(), and without any other assignment operations.
diff --git a/net/mpls/mpls_gso.c b/net/mpls/mpls_gso.c index 533d082f0701..2ab24b2fd90f 100644 --- a/net/mpls/mpls_gso.c +++ b/net/mpls/mpls_gso.c @@ -25,11 +25,11 @@ static struct sk_buff *mpls_gso_segment(struct sk_buff *skb, netdev_features_t mpls_features; u16 mac_len = skb->mac_len; __be16 mpls_protocol; - unsigned int mpls_hlen; + int mpls_hlen; skb_reset_network_header(skb); mpls_hlen = skb_inner_network_header(skb) - skb_network_header(skb); - if (unlikely(!mpls_hlen || mpls_hlen % MPLS_HLEN)) + if (unlikely(mpls_hlen <= 0 || mpls_hlen % MPLS_HLEN)) goto out; if (unlikely(!pskb_may_pull(skb, mpls_hlen))) goto out;
When the network header pointer is greater than the inner network header, the difference between the two can cause mpls_hlen overflow. Reported-and-tested-by: syzbot+99d15fcdb0132a1e1a82@syzkaller.appspotmail.com Signed-off-by: Lizhi Xu <lizhi.xu@windriver.com> --- net/mpls/mpls_gso.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)