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authorMatthew Daley <mattjd@gmail.com>2011-10-14 22:45:04 +0400
committerDavid S. Miller <davem@davemloft.net>2011-10-18 03:31:39 +0400
commitcb101ed2c3c7c0224d16953fe77bfb9d6c2cb9df (patch)
tree3d266ac18673ebc85a99e4d10d8d381ff1ebd782 /net/x25/af_x25.c
parentc7fd0d48bde943e228e9c28ce971a22d6a1744c4 (diff)
downloadlinux-cb101ed2c3c7c0224d16953fe77bfb9d6c2cb9df.tar.xz
x25: Handle undersized/fragmented skbs
There are multiple locations in the X.25 packet layer where a skb is assumed to be of at least a certain size and that all its data is currently available at skb->data. These assumptions are not checked, hence buffer overreads may occur. Use pskb_may_pull to check these minimal size assumptions and ensure that data is available at skb->data when necessary, as well as use skb_copy_bits where needed. Signed-off-by: Matthew Daley <mattjd@gmail.com> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Andrew Hendry <andrew.hendry@gmail.com> Cc: stable <stable@kernel.org> Acked-by: Andrew Hendry <andrew.hendry@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/x25/af_x25.c')
-rw-r--r--net/x25/af_x25.c31
1 files changed, 24 insertions, 7 deletions
diff --git a/net/x25/af_x25.c b/net/x25/af_x25.c
index a4bd1720e39b..aa567b09ea9a 100644
--- a/net/x25/af_x25.c
+++ b/net/x25/af_x25.c
@@ -91,7 +91,7 @@ int x25_parse_address_block(struct sk_buff *skb,
int needed;
int rc;
- if (skb->len < 1) {
+ if (!pskb_may_pull(skb, 1)) {
/* packet has no address block */
rc = 0;
goto empty;
@@ -100,7 +100,7 @@ int x25_parse_address_block(struct sk_buff *skb,
len = *skb->data;
needed = 1 + (len >> 4) + (len & 0x0f);
- if (skb->len < needed) {
+ if (!pskb_may_pull(skb, needed)) {
/* packet is too short to hold the addresses it claims
to hold */
rc = -1;
@@ -951,10 +951,10 @@ int x25_rx_call_request(struct sk_buff *skb, struct x25_neigh *nb,
*
* Facilities length is mandatory in call request packets
*/
- if (skb->len < 1)
+ if (!pskb_may_pull(skb, 1))
goto out_clear_request;
len = skb->data[0] + 1;
- if (skb->len < len)
+ if (!pskb_may_pull(skb, len))
goto out_clear_request;
skb_pull(skb,len);
@@ -965,6 +965,13 @@ int x25_rx_call_request(struct sk_buff *skb, struct x25_neigh *nb,
goto out_clear_request;
/*
+ * Get all the call user data so it can be used in
+ * x25_find_listener and skb_copy_from_linear_data up ahead.
+ */
+ if (!pskb_may_pull(skb, skb->len))
+ goto out_clear_request;
+
+ /*
* Find a listener for the particular address/cud pair.
*/
sk = x25_find_listener(&source_addr,skb);
@@ -1172,6 +1179,9 @@ static int x25_sendmsg(struct kiocb *iocb, struct socket *sock,
* byte of the user data is the logical value of the Q Bit.
*/
if (test_bit(X25_Q_BIT_FLAG, &x25->flags)) {
+ if (!pskb_may_pull(skb, 1))
+ goto out_kfree_skb;
+
qbit = skb->data[0];
skb_pull(skb, 1);
}
@@ -1250,7 +1260,9 @@ static int x25_recvmsg(struct kiocb *iocb, struct socket *sock,
struct x25_sock *x25 = x25_sk(sk);
struct sockaddr_x25 *sx25 = (struct sockaddr_x25 *)msg->msg_name;
size_t copied;
- int qbit;
+ int qbit, header_len = x25->neighbour->extended ?
+ X25_EXT_MIN_LEN : X25_STD_MIN_LEN;
+
struct sk_buff *skb;
unsigned char *asmptr;
int rc = -ENOTCONN;
@@ -1271,6 +1283,9 @@ static int x25_recvmsg(struct kiocb *iocb, struct socket *sock,
skb = skb_dequeue(&x25->interrupt_in_queue);
+ if (!pskb_may_pull(skb, X25_STD_MIN_LEN))
+ goto out_free_dgram;
+
skb_pull(skb, X25_STD_MIN_LEN);
/*
@@ -1291,10 +1306,12 @@ static int x25_recvmsg(struct kiocb *iocb, struct socket *sock,
if (!skb)
goto out;
+ if (!pskb_may_pull(skb, header_len))
+ goto out_free_dgram;
+
qbit = (skb->data[0] & X25_Q_BIT) == X25_Q_BIT;
- skb_pull(skb, x25->neighbour->extended ?
- X25_EXT_MIN_LEN : X25_STD_MIN_LEN);
+ skb_pull(skb, header_len);
if (test_bit(X25_Q_BIT_FLAG, &x25->flags)) {
asmptr = skb_push(skb, 1);