[PATCH 3.16.y-ckt 104/104] net: add length argument to skb_copy_and_csum_datagram_iovec

From: Luis Henriques
Date: Mon Oct 26 2015 - 09:46:34 EST


3.16.7-ckt19 -stable review patch. If anyone has any objections, please let me know.

------------------

From: Sabrina Dubroca <sd@xxxxxxxxxxxxxxx>

Without this length argument, we can read past the end of the iovec in
memcpy_toiovec because we have no way of knowing the total length of the
iovec's buffers.

This is needed for stable kernels where 89c22d8c3b27 ("net: Fix skb
csum races when peeking") has been backported but that don't have the
ioviter conversion, which is almost all the stable trees <= 3.18.

This also fixes a kernel crash for NFS servers when the client uses
-onfsvers=3,proto=udp to mount the export.

Signed-off-by: Sabrina Dubroca <sd@xxxxxxxxxxxxxxx>
Reviewed-by: Hannes Frederic Sowa <hannes@xxxxxxxxxxxxxxxxxxx>
[ luis: backported to 3.16:
- dropped changes to net/rxrpc/ar-recvmsg.c ]
Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx>
---
include/linux/skbuff.h | 2 +-
net/core/datagram.c | 6 +++++-
net/ipv4/tcp_input.c | 2 +-
net/ipv4/udp.c | 2 +-
net/ipv6/raw.c | 2 +-
net/ipv6/udp.c | 3 ++-
6 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 010bc80be91c..94038f93f145 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -2525,7 +2525,7 @@ unsigned int datagram_poll(struct file *file, struct socket *sock,
int skb_copy_datagram_iovec(const struct sk_buff *from, int offset,
struct iovec *to, int size);
int skb_copy_and_csum_datagram_iovec(struct sk_buff *skb, int hlen,
- struct iovec *iov);
+ struct iovec *iov, int len);
int skb_copy_datagram_from_iovec(struct sk_buff *skb, int offset,
const struct iovec *from, int from_offset,
int len);
diff --git a/net/core/datagram.c b/net/core/datagram.c
index 3c69a464595e..169f742d1464 100644
--- a/net/core/datagram.c
+++ b/net/core/datagram.c
@@ -818,6 +818,7 @@ EXPORT_SYMBOL(__skb_checksum_complete);
* @skb: skbuff
* @hlen: hardware length
* @iov: io vector
+ * @len: amount of data to copy from skb to iov
*
* Caller _must_ check that skb will fit to this iovec.
*
@@ -827,11 +828,14 @@ EXPORT_SYMBOL(__skb_checksum_complete);
* can be modified!
*/
int skb_copy_and_csum_datagram_iovec(struct sk_buff *skb,
- int hlen, struct iovec *iov)
+ int hlen, struct iovec *iov, int len)
{
__wsum csum;
int chunk = skb->len - hlen;

+ if (chunk > len)
+ chunk = len;
+
if (!chunk)
return 0;

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 486f70050563..0cdaa633059b 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -4906,7 +4906,7 @@ static int tcp_copy_to_iovec(struct sock *sk, struct sk_buff *skb, int hlen)
err = skb_copy_datagram_iovec(skb, hlen, tp->ucopy.iov, chunk);
else
err = skb_copy_and_csum_datagram_iovec(skb, hlen,
- tp->ucopy.iov);
+ tp->ucopy.iov, chunk);

if (!err) {
tp->ucopy.len -= chunk;
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 10c1530ba978..4b9e4aba11b0 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1307,7 +1307,7 @@ try_again:
else {
err = skb_copy_and_csum_datagram_iovec(skb,
sizeof(struct udphdr),
- msg->msg_iov);
+ msg->msg_iov, copied);

if (err == -EINVAL)
goto csum_copy_err;
diff --git a/net/ipv6/raw.c b/net/ipv6/raw.c
index b2dc60b0c764..fd377c4d8986 100644
--- a/net/ipv6/raw.c
+++ b/net/ipv6/raw.c
@@ -492,7 +492,7 @@ static int rawv6_recvmsg(struct kiocb *iocb, struct sock *sk,
goto csum_copy_err;
err = skb_copy_datagram_iovec(skb, 0, msg->msg_iov, copied);
} else {
- err = skb_copy_and_csum_datagram_iovec(skb, 0, msg->msg_iov);
+ err = skb_copy_and_csum_datagram_iovec(skb, 0, msg->msg_iov, copied);
if (err == -EINVAL)
goto csum_copy_err;
}
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index ad5891072a89..72603a9af4bc 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -428,7 +428,8 @@ try_again:
err = skb_copy_datagram_iovec(skb, sizeof(struct udphdr),
msg->msg_iov, copied);
else {
- err = skb_copy_and_csum_datagram_iovec(skb, sizeof(struct udphdr), msg->msg_iov);
+ err = skb_copy_and_csum_datagram_iovec(skb, sizeof(struct udphdr),
+ msg->msg_iov, copied);
if (err == -EINVAL)
goto csum_copy_err;
}
--
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