irda: prevent heap corruption on invalid nickname

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>
Cc: stable@kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 0 deletions

diff --git a/net/irda/irnet/irnet_ppp.c b/net/irda/irnet/irnet_ppp.c
index 7c567b8aa89a..2bb2beb6a373 100644
--- 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';