2.6.36-stable review patch. If anyone has any objections, please let us know.
------------------ From: Dan Rosenberg <[email protected]> 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 <[email protected]> Signed-off-by: David S. Miller <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- net/x25/x25_facilities.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) --- a/net/x25/x25_facilities.c +++ b/net/x25/x25_facilities.c @@ -61,6 +61,8 @@ int x25_parse_facilities(struct sk_buff 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 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 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 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 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; _______________________________________________ stable mailing list [email protected] http://linux.kernel.org/mailman/listinfo/stable
