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From:   Philipp Stanner <pstanner@redhat.com>
To:     Ian Abbott <abbotti@mev.co.uk>,
        H Hartley Sweeten <hsweeten@visionengravers.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Philipp Stanner <pstanner@redhat.com>,
        Ivan Orlov <ivan.orlov0322@gmail.com>,
        Benjamin Tissoires <benjamin.tissoires@redhat.com>
Cc:     linux-kernel@vger.kernel.org, Dave Airlie <airlied@redhat.com>
Subject: [PATCH] drivers/comedi: copy userspace array safely
Date:   Thu,  2 Nov 2023 20:08:49 +0100
Message-ID: <20231102190848.51376-2-pstanner@redhat.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

comedi_fops.c utilizes memdup_user() to copy a userspace array. This
does not check for an overflow.

Use the new wrapper memdup_array_user() to copy the array more safely.

Suggested-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Philipp Stanner <pstanner@redhat.com>
---
 drivers/comedi/comedi_fops.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/comedi/comedi_fops.c b/drivers/comedi/comedi_fops.c
index 1548dea15df1..1b481731df96 100644
--- a/drivers/comedi/comedi_fops.c
+++ b/drivers/comedi/comedi_fops.c
@@ -1714,8 +1714,8 @@ static int __comedi_get_user_chanlist(struct comedi_device *dev,
 
 	lockdep_assert_held(&dev->mutex);
 	cmd->chanlist = NULL;
-	chanlist = memdup_user(user_chanlist,
-			       cmd->chanlist_len * sizeof(unsigned int));
+	chanlist = memdup_array_user(user_chanlist,
+				     cmd->chanlist_len, sizeof(unsigned int));
 	if (IS_ERR(chanlist))
 		return PTR_ERR(chanlist);
 
-- 
2.41.0