From: Willem de Bruijn <will...@google.com>
Validate gso_type during segmentation as SKB_GSO_DODGY sources
may pass packets where the gso_type does not match the contents.
Syzkaller was able to enter the SCTP gso handler with a packet of
gso_type SKB_GSO_TCPV4.
On entry of transport layer gso handlers, verify that the gso_type
matches the transport protocol.
Fixes: f43798c27684 ("tun: Allow GSO using virtio_net_hdr")
Link: http://lkml.kernel.org/r/<001a1137452496ffc305617e5...@google.com>
Reported-by: syzbot+fee64147a25aecd48...@syzkaller.appspotmail.com
Signed-off-by: Willem de Bruijn <will...@google.com>
---
Similar checks existed until removed in commit 5c7cdf339af5 ("gso:
Remove arbitrary checks for unsupported GSO"). But those were limited
to the TSO path, not software GSO. I believe that this issue goes
back further, hence the Fixes at the first user of virtio_net_hdr.
---
net/ipv4/esp4_offload.c | 3 +++
net/ipv4/tcp_offload.c | 3 +++
net/ipv4/udp_offload.c | 3 +++
net/ipv6/esp6_offload.c | 3 +++
net/ipv6/tcpv6_offload.c | 3 +++
net/ipv6/udp_offload.c | 3 +++
net/sctp/offload.c | 3 +++
7 files changed, 21 insertions(+)
diff --git a/net/ipv4/esp4_offload.c b/net/ipv4/esp4_offload.c
index b1338e576d00..29b333a62ab0 100644
--- a/net/ipv4/esp4_offload.c
+++ b/net/ipv4/esp4_offload.c
@@ -122,6 +122,9 @@ static struct sk_buff *esp4_gso_segment(struct sk_buff *skb,
if (!xo)
goto out;
+ if (!(skb_shinfo(skb)->gso_type & SKB_GSO_ESP))
+ goto out;
+
seq = xo->seq.low;
x = skb->sp->xvec[skb->sp->len - 1];
diff --git a/net/ipv4/tcp_offload.c b/net/ipv4/tcp_offload.c
index b6a2aa1dcf56..4d58e2ce0b5b 100644
--- a/net/ipv4/tcp_offload.c
+++ b/net/ipv4/tcp_offload.c
@@ -32,6 +32,9 @@ static void tcp_gso_tstamp(struct sk_buff *skb, unsigned int
ts_seq,
static struct sk_buff *tcp4_gso_segment(struct sk_buff *skb,
netdev_features_t features)
{
+ if (!(skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4))
+ return ERR_PTR(-EINVAL);
+
if (!pskb_may_pull(skb, sizeof(struct tcphdr)))
return ERR_PTR(-EINVAL);
diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c
index 01801b77bd0d..ea6e6e7df0ee 100644
--- a/net/ipv4/udp_offload.c
+++ b/net/ipv4/udp_offload.c
@@ -203,6 +203,9 @@ static struct sk_buff *udp4_ufo_fragment(struct sk_buff
*skb,
goto out;
}
+ if (!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP))
+ goto out;
+
if (!pskb_may_pull(skb, sizeof(struct udphdr)))
goto out;
diff --git a/net/ipv6/esp6_offload.c b/net/ipv6/esp6_offload.c
index dd9627490c7c..f52c314d4c97 100644
--- a/net/ipv6/esp6_offload.c
+++ b/net/ipv6/esp6_offload.c
@@ -149,6 +149,9 @@ static struct sk_buff *esp6_gso_segment(struct sk_buff *skb,
if (!xo)
goto out;
+ if (!(skb_shinfo(skb)->gso_type & SKB_GSO_ESP))
+ goto out;
+
seq = xo->seq.low;
x = skb->sp->xvec[skb->sp->len - 1];
diff --git a/net/ipv6/tcpv6_offload.c b/net/ipv6/tcpv6_offload.c
index d883c9204c01..278e49cd67d4 100644
--- a/net/ipv6/tcpv6_offload.c
+++ b/net/ipv6/tcpv6_offload.c
@@ -46,6 +46,9 @@ static struct sk_buff *tcp6_gso_segment(struct sk_buff *skb,
{
struct tcphdr *th;
+ if (!(skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6))
+ return ERR_PTR(-EINVAL);
+
if (!pskb_may_pull(skb, sizeof(*th)))
return ERR_PTR(-EINVAL);
diff --git a/net/ipv6/udp_offload.c b/net/ipv6/udp_offload.c
index a0f89ad76f9d..2a04dc9c781b 100644
--- a/net/ipv6/udp_offload.c
+++ b/net/ipv6/udp_offload.c
@@ -42,6 +42,9 @@ static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb,
const struct ipv6hdr *ipv6h;
struct udphdr *uh;
+ if (!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP))
+ goto out;
+
if (!pskb_may_pull(skb, sizeof(struct udphdr)))
goto out;
diff --git a/net/sctp/offload.c b/net/sctp/offload.c
index 275925b93b29..35bc7106d182 100644
--- a/net/sctp/offload.c
+++ b/net/sctp/offload.c
@@ -45,6 +45,9 @@ static struct sk_buff *sctp_gso_segment(struct sk_buff *skb,
struct sk_buff *segs = ERR_PTR(-EINVAL);
struct sctphdr *sh;
+ if (!(skb_shinfo(skb)->gso_type & SKB_GSO_SCTP))
+ goto out;
+
sh = sctp_hdr(skb);
if (!pskb_may_pull(skb, sizeof(*sh)))
goto out;
--
2.16.0.rc1.238.g530d649a79-goog
