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Commit b43f5c7f authored by Oscar Maes's avatar Oscar Maes Committed by Greg Kroah-Hartman
Browse files

net: ipv4: fix regression in local-broadcast routes 



[ Upstream commit 5189446ba995556eaa3755a6e875bc06675b88bd ]

Commit 9e30ecf23b1b ("net: ipv4: fix incorrect MTU in broadcast routes")
introduced a regression where local-broadcast packets would have their
gateway set in __mkroute_output, which was caused by fi = NULL being
removed.

Fix this by resetting the fib_info for local-broadcast packets. This
preserves the intended changes for directed-broadcast packets.

Cc: stable@vger.kernel.org
Fixes: 9e30ecf23b1b ("net: ipv4: fix incorrect MTU in broadcast routes")
Reported-by: default avatarBrett A C Sheffield <bacs@librecast.net>
Closes: https://lore.kernel.org/regressions/20250822165231.4353-4-bacs@librecast.net


Signed-off-by: default avatarOscar Maes <oscmaes92@gmail.com>
Reviewed-by: default avatarDavid Ahern <dsahern@kernel.org>
Link: https://patch.msgid.link/20250827062322.4807-1-oscmaes92@gmail.com


Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 821193f4

net/ipv4/route.c

+7 −3
Original line number Diff line number Diff line
@@ -2365,12 +2365,16 @@ static struct rtable *__mkroute_output(const struct fib_result *res, 
		    !netif_is_l3_master(dev_out))

			return ERR_PTR(-EINVAL);



	if (ipv4_is_lbcast(fl4->daddr))

	if (ipv4_is_lbcast(fl4->daddr)) {

		type = RTN_BROADCAST;

	else if (ipv4_is_multicast(fl4->daddr))



		/* reset fi to prevent gateway resolution */

		fi = NULL;

	} else if (ipv4_is_multicast(fl4->daddr)) {

		type = RTN_MULTICAST;

	else if (ipv4_is_zeronet(fl4->daddr))

	} else if (ipv4_is_zeronet(fl4->daddr)) {

		return ERR_PTR(-EINVAL);

	}



	if (dev_out->flags & IFF_LOOPBACK)

		flags |= RTCF_LOCAL;