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authorMatthew Daley <mattjd@gmail.com>2011-10-14 18:45:04 +0000
committerDavid S. Miller <davem@davemloft.net>2011-10-17 19:31:39 -0400
commitcb101ed2c3c7c0224d16953fe77bfb9d6c2cb9df (patch)
tree3d266ac18673ebc85a99e4d10d8d381ff1ebd782 /net/x25/x25_subr.c
parentc7fd0d48bde943e228e9c28ce971a22d6a1744c4 (diff)
downloadlinux-cb101ed2c3c7c0224d16953fe77bfb9d6c2cb9df.tar.bz2
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/x25_subr.c')
-rw-r--r--net/x25/x25_subr.c14
1 files changed, 13 insertions, 1 deletions
diff --git a/net/x25/x25_subr.c b/net/x25/x25_subr.c
index 24a342ebc7f5..5170d52bfd96 100644
--- a/net/x25/x25_subr.c
+++ b/net/x25/x25_subr.c
@@ -269,7 +269,11 @@ int x25_decode(struct sock *sk, struct sk_buff *skb, int *ns, int *nr, int *q,
int *d, int *m)
{
struct x25_sock *x25 = x25_sk(sk);
- unsigned char *frame = skb->data;
+ unsigned char *frame;
+
+ if (!pskb_may_pull(skb, X25_STD_MIN_LEN))
+ return X25_ILLEGAL;
+ frame = skb->data;
*ns = *nr = *q = *d = *m = 0;
@@ -294,6 +298,10 @@ int x25_decode(struct sock *sk, struct sk_buff *skb, int *ns, int *nr, int *q,
if (frame[2] == X25_RR ||
frame[2] == X25_RNR ||
frame[2] == X25_REJ) {
+ if (!pskb_may_pull(skb, X25_EXT_MIN_LEN))
+ return X25_ILLEGAL;
+ frame = skb->data;
+
*nr = (frame[3] >> 1) & 0x7F;
return frame[2];
}
@@ -308,6 +316,10 @@ int x25_decode(struct sock *sk, struct sk_buff *skb, int *ns, int *nr, int *q,
if (x25->neighbour->extended) {
if ((frame[2] & 0x01) == X25_DATA) {
+ if (!pskb_may_pull(skb, X25_EXT_MIN_LEN))
+ return X25_ILLEGAL;
+ frame = skb->data;
+
*q = (frame[0] & X25_Q_BIT) == X25_Q_BIT;
*d = (frame[0] & X25_D_BIT) == X25_D_BIT;
*m = (frame[3] & X25_EXT_M_BIT) == X25_EXT_M_BIT;