[patch 15/33] Fix memory corruption in console selection

[Greg KH]

2.6.28-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Mikulas Patocka <mpatocka@xxxxxxxxxx>

commit 878b8619f711280fd05845e21956434b5e588cc4 upstream.

Fix an off-by-two memory error in console selection.

The loop below goes from sel_start to sel_end (inclusive), so it writes
one more character.  This one more character was added to the allocated
size (+1), but it was not multiplied by an UTF-8 multiplier.

This patch fixes a memory corruption when UTF-8 console is used and the
user selects a few characters, all of them 3-byte in UTF-8 (for example
a frame line).

When memory redzones are enabled, a redzone corruption is reported.
When they are not enabled, trashing of random memory occurs.

Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 drivers/char/selection.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/char/selection.c
+++ b/drivers/char/selection.c
@@ -268,7 +268,7 @@ int set_selection(const struct tiocl_sel
 
 	/* Allocate a new buffer before freeing the old one ... */
 	multiplier = use_unicode ? 3 : 1;  /* chars can take up to 3 bytes */
-	bp = kmalloc((sel_end-sel_start)/2*multiplier+1, GFP_KERNEL);
+	bp = kmalloc(((sel_end-sel_start)/2+1)*multiplier, GFP_KERNEL);
 	if (!bp) {
 		printk(KERN_WARNING "selection: kmalloc() failed\n");
 		clear_selection();

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