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 7dea882dbb750649b10616f00dcb9bb68697ec64..38997cdcda403f791ccb5148e902ed2018462103 100644 (file)
--- a/net/irda/irnet/irnet_ppp.c
+++ b/net/irda/irnet/irnet_ppp.c
@@ -106,6 +106,9 @@ 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';