Received-SPF: softfail (google.com: domain of transitioning linux-kernel-owner@vger.kernel.org does not designate 23.128.96.19 as permitted sender) client-ip=23.128.96.19;
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Derek Will <derekrobertwill@gmail.com>,
        Oliver Hartkopp <socketcan@hartkopp.net>,
        Marc Kleine-Budde <mkl@pengutronix.de>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.10 571/599] can: isotp: restore accidentally removed MSG_PEEK feature
Date:   Tue,  5 Apr 2022 09:34:25 +0200
Message-Id: <20220405070315.834665766@linuxfoundation.org>
In-Reply-To: <20220405070258.802373272@linuxfoundation.org>
References: <20220405070258.802373272@linuxfoundation.org>
User-Agent: quilt/0.66
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Precedence: bulk

From: Oliver Hartkopp <socketcan@hartkopp.net>

[ Upstream commit e382fea8ae54f5bb62869c6b69b33993d43adeca ]

In commit 42bf50a1795a ("can: isotp: support MSG_TRUNC flag when
reading from socket") a new check for recvmsg flags has been
introduced that only checked for the flags that are handled in
isotp_recvmsg() itself.

This accidentally removed the MSG_PEEK feature flag which is processed
later in the call chain in __skb_try_recv_from_queue().

Add MSG_PEEK to the set of valid flags to restore the feature.

Fixes: 42bf50a1795a ("can: isotp: support MSG_TRUNC flag when reading from socket")
Link: https://github.com/linux-can/can-utils/issues/347#issuecomment-1079554254
Link: https://lore.kernel.org/all/20220328113611.3691-1-socketcan@hartkopp.net
Reported-by: Derek Will <derekrobertwill@gmail.com>
Suggested-by: Derek Will <derekrobertwill@gmail.com>
Tested-by: Derek Will <derekrobertwill@gmail.com>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/can/isotp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/can/isotp.c b/net/can/isotp.c
index 671c3673b7ea..63e6e8923200 100644
--- a/net/can/isotp.c
+++ b/net/can/isotp.c
@@ -1007,7 +1007,7 @@ static int isotp_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
 	int noblock = flags & MSG_DONTWAIT;
 	int ret = 0;
 
-	if (flags & ~(MSG_DONTWAIT | MSG_TRUNC))
+	if (flags & ~(MSG_DONTWAIT | MSG_TRUNC | MSG_PEEK))
 		return -EINVAL;
 
 	if (!so->bound)
-- 
2.34.1