linux-kernel - [PATCH] drivers/net/ppp: copy userspace array safely

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Message-ID: <20231102191914.52957-2-pstanner@redhat.com>
Date:   Thu,  2 Nov 2023 20:19:15 +0100
From:   Philipp Stanner <pstanner@...hat.com>
To:     "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Stanislav Fomichev <sdf@...gle.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Benjamin Tissoires <benjamin.tissoires@...hat.com>,
        Al Viro <viro@...iv.linux.org.uk>
Cc:     linux-ppp@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Philipp Stanner <pstanner@...hat.com>,
        Dave Airlie <airlied@...hat.com>
Subject: [PATCH] drivers/net/ppp: copy userspace array safely

In ppp_generic.c memdup_user() is utilized to copy a userspace array.
This is done without an overflow check.

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

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

diff --git a/drivers/net/ppp/ppp_generic.c b/drivers/net/ppp/ppp_generic.c
index a9beacd552cf..0193af2d31c9 100644
--- a/drivers/net/ppp/ppp_generic.c
+++ b/drivers/net/ppp/ppp_generic.c
@@ -570,8 +570,8 @@ static struct bpf_prog *get_filter(struct sock_fprog *uprog)
 
 	/* uprog->len is unsigned short, so no overflow here */
 	fprog.len = uprog->len;
-	fprog.filter = memdup_user(uprog->filter,
-				   uprog->len * sizeof(struct sock_filter));
+	fprog.filter = memdup_array_user(uprog->filter,
+					 uprog->len, sizeof(struct sock_filter));
 	if (IS_ERR(fprog.filter))
 		return ERR_CAST(fprog.filter);
 
-- 
2.41.0