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x25: possible skb leak on bad facilities

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Originally x25_parse_facilities returned
-1 for an error
 0 meaning 0 length facilities
>0 the length of the facilities parsed.

5ef41308f9 ("x25: Prevent crashing when parsing bad X.25 facilities") introduced more
error checking in x25_parse_facilities however used 0 to indicate bad parsing
a6331d6f9a ("memory corruption in X.25 facilities parsing") followed this further for
DTE facilities, again using 0 for bad parsing.

The meaning of 0 got confused in the callers.
If the facilities are messed up we can't determine where the data starts.
So patch makes all parsing errors return -1 and ensures callers close and don't use the skb further.

Reported-by: Andy Whitcroft <apw@canonical.com>
Signed-off-by: Andrew Hendry <andrew.hendry@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
andrew hendry
2011-02-07 00:08:15 +00:00
committed by David S. Miller
parent 711c914688
commit 95c3043008
2 changed files with 30 additions and 12 deletions
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14
net/x25/x25_in.c
View File

@@ -91,10 +91,10 @@ static int x25_state1_machine(struct sock *sk, struct sk_buff *skb, int frametyp
{
struct x25_address source_addr, dest_addr;
int len;
struct x25_sock *x25 = x25_sk(sk);
switch (frametype) {
case X25_CALL_ACCEPTED: {
struct x25_sock *x25 = x25_sk(sk);
x25_stop_timer(sk);
x25->condition = 0x00;
@@ -113,14 +113,16 @@ static int x25_state1_machine(struct sock *sk, struct sk_buff *skb, int frametyp
&dest_addr);
if (len > 0)
skb_pull(skb, len);
else if (len < 0)
goto out_clear;
len = x25_parse_facilities(skb, &x25->facilities,
&x25->dte_facilities,
&x25->vc_facil_mask);
if (len > 0)
skb_pull(skb, len);
else
return -1;
else if (len < 0)
goto out_clear;
/*
* Copy any Call User Data.
*/
@@ -144,6 +146,12 @@ static int x25_state1_machine(struct sock *sk, struct sk_buff *skb, int frametyp
}
return 0;
out_clear:
x25_write_internal(sk, X25_CLEAR_REQUEST);
x25->state = X25_STATE_2;
x25_start_t23timer(sk);
return 0;
}
/*