linux-kernel - [PATCH net 1/2] net: bridge: fix ioctl old

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Message-Id: <20211223153139.7661-2-repk@triplefau.lt>
Date:   Thu, 23 Dec 2021 16:31:38 +0100
From:   Remi Pommarel <repk@...plefau.lt>
To:     netdev@...r.kernel.org
Cc:     Roopa Prabhu <roopa@...dia.com>,
        Nikolay Aleksandrov <nikolay@...dia.com>,
        Arnd Bergmann <arnd@...db.de>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        bridge@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        Remi Pommarel <repk@...plefau.lt>
Subject: [PATCH net 1/2] net: bridge: fix ioctl old_deviceless bridge argument

Commit 561d8352818f ("bridge: use ndo_siocdevprivate") changed the
source and destination arguments of copy_{to,from}_user in bridge's
old_deviceless() from args[1] to uarg breaking SIOC{G,S}IFBR ioctls.

Commit cbd7ad29a507 ("net: bridge: fix ioctl old_deviceless bridge
argument") fixed only BRCTL_{ADD,DEL}_BRIDGES commands leaving
BRCTL_GET_BRIDGES one untouched.

The fixes BRCTL_GET_BRIDGES as well and has been tested with busybox's
brctl.

Example of broken brctl:
$ brctl show
bridge name     bridge id               STP enabled     interfaces
brctl: can't get bridge name for index 0: No such device or address

Example of fixed brctl:
$ brctl show
bridge name     bridge id               STP enabled     interfaces
br0             8000.000000000000       no

Fixes: 561d8352818f ("bridge: use ndo_siocdevprivate")
Signed-off-by: Remi Pommarel <repk@...plefau.lt>
Reviewed-by: Arnd Bergmann <arnd@...db.de>
Acked-by: Nikolay Aleksandrov <nikolay@...dia.com>
---
 net/bridge/br_ioctl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/bridge/br_ioctl.c b/net/bridge/br_ioctl.c
index db4ab2c2ce18..891cfcf45644 100644
--- a/net/bridge/br_ioctl.c
+++ b/net/bridge/br_ioctl.c
@@ -337,7 +337,7 @@ static int old_deviceless(struct net *net, void __user *uarg)
 
 		args[2] = get_bridge_ifindices(net, indices, args[2]);
 
-		ret = copy_to_user(uarg, indices,
+		ret = copy_to_user((void __user *)args[1], indices,
 				   array_size(args[2], sizeof(int)))
 			? -EFAULT : args[2];
 
-- 
2.33.0