Patch "net: socket: fix recvmmsg not returning error from sock_error" has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    net: socket: fix recvmmsg not returning error from sock_error

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     net-socket-fix-recvmmsg-not-returning-error-from-sock_error.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Thu Feb 23 21:13:19 CET 2017
From: Maxime Jayat <maxime.jayat@mobile-devices.fr>
Date: Tue, 21 Feb 2017 18:35:51 +0100
Subject: net: socket: fix recvmmsg not returning error from sock_error

From: Maxime Jayat <maxime.jayat@mobile-devices.fr>


[ Upstream commit e623a9e9dec29ae811d11f83d0074ba254aba374 ]

Commit 34b88a68f26a ("net: Fix use after free in the recvmmsg exit path"),
changed the exit path of recvmmsg to always return the datagrams
variable and modified the error paths to set the variable to the error
code returned by recvmsg if necessary.

However in the case sock_error returned an error, the error code was
then ignored, and recvmmsg returned 0.

Change the error path of recvmmsg to correctly return the error code
of sock_error.

The bug was triggered by using recvmmsg on a CAN interface which was
not up. Linux 4.6 and later return 0 in this case while earlier
releases returned -ENETDOWN.

Fixes: 34b88a68f26a ("net: Fix use after free in the recvmmsg exit path")
Signed-off-by: Maxime Jayat <maxime.jayat@mobile-devices.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/socket.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/net/socket.c
+++ b/net/socket.c
@@ -2185,8 +2185,10 @@ int __sys_recvmmsg(int fd, struct mmsghd
 		return err;
 
 	err = sock_error(sock->sk);
-	if (err)
+	if (err) {
+		datagrams = err;
 		goto out_put;
+	}
 
 	entry = mmsg;
 	compat_entry = (struct compat_mmsghdr __user *)mmsg;


Patches currently in stable-queue which might be from maxime.jayat@mobile-devices.fr are

queue-4.4/net-socket-fix-recvmmsg-not-returning-error-from-sock_error.patch