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authorDan Rosenberg <drosenberg@vsecurity.com>2010-11-12 12:44:42 -0800
committerGreg Kroah-Hartman <gregkh@suse.de>2011-03-21 12:44:17 -0700
commit9cff69da3eb80877cf7efd51c777707e7561537f (patch)
tree3a01470486fab1ac0c2357590ad7506b6df6ee47 /net
parentb534a83f55a6c4ca6ad9e54148df9b94e1c46010 (diff)
x25: Prevent crashing when parsing bad X.25 facilities
commit 5ef41308f94dcbb3b7afc56cdef1c2ba53fa5d2f upstream. 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> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'net')
-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 79cf932dddde..804afd3a1f7a 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;