[PATCH] irda: prevent heap corruption on invalid nickname

[Dan Rosenberg <drosenberg@vsecurity.com>]

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

Signed-off-by: Dan Rosenberg <drosenberg@vsecurity.com>
Cc: stable@kernel.org
---
 net/irda/irnet/irnet_ppp.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/net/irda/irnet/irnet_ppp.c b/net/irda/irnet/irnet_ppp.c
index 7c567b8..881ee51 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, -EINVAL,
+		     CTRL_ERROR, "Invalid nickname.\n");
+
 	      /* Copy the name for later reuse */
 	      memcpy(ap->rname, start + 5, length - 5);
 	      ap->rname[length - 5] = '\0';