Patch "net: fix dev_fill_forward_path with pppoe + bridge" has been added to the 5.17-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

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

    net: fix dev_fill_forward_path with pppoe + bridge

to the 5.17-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-fix-dev_fill_forward_path-with-pppoe-bridge.patch
and it can be found in the queue-5.17 subdirectory.

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



commit 74418e577755a8e710b5609b49222cfd6f31da4b
Author: Felix Fietkau <nbd@xxxxxxxx>
Date:   Mon May 9 14:26:15 2022 +0200

    net: fix dev_fill_forward_path with pppoe + bridge
    
    [ Upstream commit cf2df74e202d81b09f09d84c2d8903e0e87e9274 ]
    
    When calling dev_fill_forward_path on a pppoe device, the provided destination
    address is invalid. In order for the bridge fdb lookup to succeed, the pppoe
    code needs to update ctx->daddr to the correct value.
    Fix this by storing the address inside struct net_device_path_ctx
    
    Fixes: f6efc675c9dd ("net: ppp: resolve forwarding path for bridge pppoe devices")
    Signed-off-by: Felix Fietkau <nbd@xxxxxxxx>
    Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/net/ppp/pppoe.c b/drivers/net/ppp/pppoe.c
index 3619520340b7..e172743948ed 100644
--- a/drivers/net/ppp/pppoe.c
+++ b/drivers/net/ppp/pppoe.c
@@ -988,6 +988,7 @@ static int pppoe_fill_forward_path(struct net_device_path_ctx *ctx,
 	path->encap.proto = htons(ETH_P_PPP_SES);
 	path->encap.id = be16_to_cpu(po->num);
 	memcpy(path->encap.h_dest, po->pppoe_pa.remote, ETH_ALEN);
+	memcpy(ctx->daddr, po->pppoe_pa.remote, ETH_ALEN);
 	path->dev = ctx->dev;
 	ctx->dev = dev;
 
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index f53ea7038441..dadd4d2f6d8a 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -891,7 +891,7 @@ struct net_device_path_stack {
 
 struct net_device_path_ctx {
 	const struct net_device *dev;
-	const u8		*daddr;
+	u8			daddr[ETH_ALEN];
 
 	int			num_vlans;
 	struct {
diff --git a/net/core/dev.c b/net/core/dev.c
index 91cf709c98b3..5f1ac4812277 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -663,11 +663,11 @@ int dev_fill_forward_path(const struct net_device *dev, const u8 *daddr,
 	const struct net_device *last_dev;
 	struct net_device_path_ctx ctx = {
 		.dev	= dev,
-		.daddr	= daddr,
 	};
 	struct net_device_path *path;
 	int ret = 0;
 
+	memcpy(ctx.daddr, daddr, sizeof(ctx.daddr));
 	stack->num_paths = 0;
 	while (ctx.dev && ctx.dev->netdev_ops->ndo_fill_forward_path) {
 		last_dev = ctx.dev;