irda: prevent heap corruption on invalid nickname

commit d50e7e3604778bfc2dc40f440e0742dbae399d54 upstream.

Invalid nicknames containing only spaces will result in an underflow in
a memcpy size calculation, subsequently destroying the heap and
panicking.

v2 also catches the case where the provided nickname is longer than the
buffer size, which can result in controllable heap corruption.

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>

diff --git a/net/irda/irnet/irnet_ppp.c b/net/irda/irnet/irnet_ppp.c
index 6b3602de359ae556761ec10effa42151c0a92817..581f2529014d47417db5e79e17f50356c2858619 100644 (file)
--- a/net/irda/irnet/irnet_ppp.c
+++ b/net/irda/irnet/irnet_ppp.c
@@ -105,6 +105,9 @@ irnet_ctrl_write(irnet_socket *     ap,
              while(isspace(start[length - 1]))
                length--;
 
+             DABORT(length < 5 || length > NICKNAME_MAX_LEN + 5,
+                    -EINVAL, CTRL_ERROR, "Invalid nickname.\n");
+
              /* Copy the name for later reuse */
              memcpy(ap->rname, start + 5, length - 5);
              ap->rname[length - 5] = '\0';