From cb101ed2c3c7c0224d16953fe77bfb9d6c2cb9df Mon Sep 17 00:00:00 2001 From: Matthew Daley Date: Fri, 14 Oct 2011 18:45:04 +0000 Subject: 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 Cc: Eric Dumazet Cc: Andrew Hendry Cc: stable Acked-by: Andrew Hendry Signed-off-by: David S. Miller --- net/x25/af_x25.c | 31 ++++++++++++++++++++++++------- 1 file changed, 24 insertions(+), 7 deletions(-) (limited to 'net/x25/af_x25.c') diff --git a/net/x25/af_x25.c b/net/x25/af_x25.c index a4bd172..aa567b0 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); -- cgit v1.1