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x25: Handle undersized/fragmented skbs

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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>
This commit is contained in:
Matthew Daley
2011-10-14 18:45:04 +00:00
committed by David S. Miller
parent c7fd0d48bd
commit cb101ed2c3
6 changed files with 87 additions and 17 deletions
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14
net/x25/x25_subr.c
View File

@@ -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;