FAILED: patch "[PATCH] ipv4: fix source address selection with route leak" failed to apply to 5.10-stable tree

The patch below does not apply to the 5.10-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y
git checkout FETCH_HEAD
git cherry-pick -x 6807352353561187a718e87204458999dbcbba1b
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2024072908-desolate-jeeringly-c274@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^..

Possible dependencies:

680735235356 ("ipv4: fix source address selection with route leak")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 6807352353561187a718e87204458999dbcbba1b Mon Sep 17 00:00:00 2001
From: Nicolas Dichtel <[email protected]>
Date: Wed, 10 Jul 2024 10:14:27 +0200
Subject: [PATCH] ipv4: fix source address selection with route leak

By default, an address assigned to the output interface is selected when the source address is not specified. This is problematic when a route, configured in a vrf, uses an interface from another vrf (aka route leak). The original vrf does not own the selected source address.

Let's add a check against the output interface and call the appropriate function to select the source address.

index f669da98d11d..8956026bc0a2 100644
@@ -2270,6 +2270,15 @@ void fib_select_path(struct net *net, struct fib_result *res,
 		fib_select_default(fl4, res);
 
 check_saddr:
-	if (!fl4->saddr)
-		fl4->saddr = fib_result_prefsrc(net, res);
+	if (!fl4->saddr) {
+		struct net_device *l3mdev;
+
+		l3mdev = dev_get_by_index_rcu(net, fl4->flowi4_l3mdev);
+
+		if (!l3mdev ||
+		    l3mdev_master_dev_rcu(FIB_RES_DEV(*res)) == l3mdev)
+			fl4->saddr = fib_result_prefsrc(net, res);
+		else
+			fl4->saddr = inet_select_addr(l3mdev, 0, RT_SCOPE_LINK);
+	}
 }