[PATCH] Fix memory leak in vc_resize/vc_allocate

[Catalin Marinas <catalin.marinas@arm.com>]

From: Catalin Marinas <catalin.marinas@arm.com>

Memory leaks can happen in the vc_resize() function in drivers/char/vt.c
because of the vc->vc_screenbuf variable overriding in vc_allocate(). The
kmemleak reported trace is as follows:

  <__kmalloc>
  <vc_resize>
  <fbcon_init>
  <visual_init>
  <vc_allocate>
  <con_open>
  <tty_open>
  <chrdev_open>

This patch no longer allocates a screen buffer in vc_allocate() if it was
already allocated by vc_resize().

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
---

 drivers/char/vt.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/drivers/char/vt.c b/drivers/char/vt.c
index da7e66a..31c8b32 100644
--- a/drivers/char/vt.c
+++ b/drivers/char/vt.c
@@ -730,7 +730,8 @@ int vc_allocate(unsigned int currcons)	/
 	    visual_init(vc, currcons, 1);
 	    if (!*vc->vc_uni_pagedir_loc)
 		con_set_default_unimap(vc);
-	    vc->vc_screenbuf = kmalloc(vc->vc_screenbuf_size, GFP_KERNEL);
+	    if (!vc->vc_kmalloced)
+		vc->vc_screenbuf = kmalloc(vc->vc_screenbuf_size, GFP_KERNEL);
 	    if (!vc->vc_screenbuf) {
 		kfree(vc);
 		vc_cons[currcons].d = NULL;