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Fix memory corruption in console selection

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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@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Mikulas Patocka 2009-01-30 15:27:14 -05:00 committed by Linus Torvalds
parent f984d02419
commit 878b8619f7
1 changed files with 1 additions and 1 deletions
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2
drivers/char/selection.c
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@ -268,7 +268,7 @@ int set_selection(const struct tiocl_selection __user *sel, struct tty_struct *t
/* Allocate a new buffer before freeing the old one ... */ /* Allocate a new buffer before freeing the old one ... */
multiplier = use_unicode ? 3 : 1; /* chars can take up to 3 bytes */ 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) { if (!bp) {
printk(KERN_WARNING "selection: kmalloc() failed\n"); printk(KERN_WARNING "selection: kmalloc() failed\n");
clear_selection(); clear_selection();