[PATCH 3.18 24/24] cdrom: information leak in cdrom_ioctl_media_changed()

From: Greg Kroah-Hartman
Date: Fri Apr 27 2018 - 10:00:23 EST

3.18-stable review patch. If anyone has any objections, please let me know.


From: Dan Carpenter <dan.carpenter@xxxxxxxxxx>

commit 9de4ee40547fd315d4a0ed1dd15a2fa3559ad707 upstream.

This cast is wrong. "cdi->capacity" is an int and "arg" is an unsigned
long. The way the check is written now, if one of the high 32 bits is
set then we could read outside the info->slots[] array.

This bug is pretty old and it predates git.

Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

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

--- a/drivers/cdrom/cdrom.c
+++ b/drivers/cdrom/cdrom.c
@@ -2357,7 +2357,7 @@ static int cdrom_ioctl_media_changed(str
return media_changed(cdi, 1);

- if ((unsigned int)arg >= cdi->capacity)
+ if (arg >= cdi->capacity)
return -EINVAL;

info = kmalloc(sizeof(*info), GFP_KERNEL);