linux-kernel - [PATCH 3.2 024/153] cdrom: information leak in cdrom_ioctl_media

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Date:   Wed, 30 May 2018 11:52:41 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Christoph Hellwig" <hch@....de>,
        "Jens Axboe" <axboe@...nel.dk>,
        "Dan Carpenter" <dan.carpenter@...cle.com>
Subject: [PATCH 3.2 024/153] cdrom: information leak in cdrom_ioctl_media_changed()

3.2.102-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Dan Carpenter <dan.carpenter@...cle.com>

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@....de>
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/cdrom/cdrom.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/cdrom/cdrom.c
+++ b/drivers/cdrom/cdrom.c
@@ -2342,7 +2342,7 @@ 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);