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authorDan Rosenberg <drosenberg@vsecurity.com>2010-11-12 12:44:42 -0800
committerDavid S. Miller <davem@davemloft.net>2010-11-12 12:44:42 -0800
commit5ef41308f94dcbb3b7afc56cdef1c2ba53fa5d2f (patch)
treec21d9c1c7f2792b0889432988d42e9b90f953358 /net/x25
parente68e6133e2daef6fc40e91621a1e26938e428e9e (diff)
x25: Prevent crashing when parsing bad X.25 facilities
Now with improved comma support. On parsing malformed X.25 facilities, decrementing the remaining length may cause it to underflow. Since the length is an unsigned integer, this will result in the loop continuing until the kernel crashes. This patch adds checks to ensure decrementing the remaining length does not cause it to wrap around. Signed-off-by: Dan Rosenberg <drosenberg@vsecurity.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/x25')
-rw-r--r--net/x25/x25_facilities.c12
1 files changed, 9 insertions, 3 deletions
diff --git a/net/x25/x25_facilities.c b/net/x25/x25_facilities.c
index 3a8c4c419cd4..55187c8f6420 100644
--- a/net/x25/x25_facilities.c
+++ b/net/x25/x25_facilities.c
@@ -61,6 +61,8 @@ int x25_parse_facilities(struct sk_buff *skb, struct x25_facilities *facilities,
while (len > 0) {
switch (*p & X25_FAC_CLASS_MASK) {
case X25_FAC_CLASS_A:
+ if (len < 2)
+ return 0;
switch (*p) {
case X25_FAC_REVERSE:
if((p[1] & 0x81) == 0x81) {
@@ -104,6 +106,8 @@ int x25_parse_facilities(struct sk_buff *skb, struct x25_facilities *facilities,
len -= 2;
break;
case X25_FAC_CLASS_B:
+ if (len < 3)
+ return 0;
switch (*p) {
case X25_FAC_PACKET_SIZE:
facilities->pacsize_in = p[1];
@@ -125,6 +129,8 @@ int x25_parse_facilities(struct sk_buff *skb, struct x25_facilities *facilities,
len -= 3;
break;
case X25_FAC_CLASS_C:
+ if (len < 4)
+ return 0;
printk(KERN_DEBUG "X.25: unknown facility %02X, "
"values %02X, %02X, %02X\n",
p[0], p[1], p[2], p[3]);
@@ -132,6 +138,8 @@ int x25_parse_facilities(struct sk_buff *skb, struct x25_facilities *facilities,
len -= 4;
break;
case X25_FAC_CLASS_D:
+ if (len < p[1] + 2)
+ return 0;
switch (*p) {
case X25_FAC_CALLING_AE:
if (p[1] > X25_MAX_DTE_FACIL_LEN || p[1] <= 1)
@@ -149,9 +157,7 @@ int x25_parse_facilities(struct sk_buff *skb, struct x25_facilities *facilities,
break;
default:
printk(KERN_DEBUG "X.25: unknown facility %02X,"
- "length %d, values %02X, %02X, "
- "%02X, %02X\n",
- p[0], p[1], p[2], p[3], p[4], p[5]);
+ "length %d\n", p[0], p[1]);
break;
}
len -= p[1] + 2;

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