[34-longterm 151/247] keyboard: integer underflow bug

From: Paul Gortmaker
Date: Thu Jun 23 2011 - 14:02:47 EST

From: Dan Carpenter <error27@xxxxxxxxx>

This is a commit scheduled for the next v2.6.34 longterm release.
If you see a problem with using this for longterm, please comment.

commit b652277b09d3d030cb074cc6a98ba80b34244c03 upstream.

The "ct" variable should be an unsigned int. Both struct kbdiacrs
->kb_cnt and struct kbd_data ->accent_table_size are unsigned ints.

Making it signed causes a problem in KBDIACRUC because the user could
set the signed bit and cause a buffer overflow.

Signed-off-by: Dan Carpenter <error27@xxxxxxxxx>
Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Signed-off-by: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
drivers/s390/char/keyboard.c | 3 ++-
1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/drivers/s390/char/keyboard.c b/drivers/s390/char/keyboard.c
index cb6bffe..84d08f9 100644
--- a/drivers/s390/char/keyboard.c
+++ b/drivers/s390/char/keyboard.c
@@ -463,7 +463,8 @@ kbd_ioctl(struct kbd_data *kbd, struct file *file,
unsigned int cmd, unsigned long arg)
void __user *argp;
- int ct, perm;
+ unsigned int ct;
+ int perm;

argp = (void __user *)arg;


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