--- /dev/null
+From 7b337c6f0dc275903224bf1e2684cc5bbe25ae0a Mon Sep 17 00:00:00 2001
+From: Sasha Levin <sashal@kernel.org>
+Date: Mon, 28 Mar 2022 13:36:11 +0200
+Subject: can: isotp: restore accidentally removed MSG_PEEK feature
+
+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 ad61342d2e16..a95d171b3a64 100644
+--- a/net/can/isotp.c
++++ b/net/can/isotp.c
+@@ -1009,7 +1009,7 @@ 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
+