[PATCH 3.16 035/410] cdrom: information leak in cdrom_ioctl_media_changed()

From: Ben Hutchings
Date: Thu Jun 07 2018 - 11:05:18 EST


3.16.57-rc1 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>
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
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
if (!CDROM_CAN(CDC_SELECT_DISC) || arg == CDSL_CURRENT)
return media_changed(cdi, 1);

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

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