From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1233237F0E4; Mon, 9 Feb 2026 14:39:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770647998; cv=none; b=CdSS/vGDcreM95Mrv33zLShN7eOys/qp4NagNgEtMEvH7KAUhaJKhlllJL6IYI35vKSmg3nr+p05+WK2YsIp3AEIXK7jdwSITg+sHGbsXAOuaAgnW1mI7nmRq/8vNZAWi0BrxH1RiP02t4L5Wv0wC7Nzri4EQXU2gAN/RPVfJPw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770647998; c=relaxed/simple; bh=f0MbFLYMpQD4rYbvDBKJG1X4IFZvRGh+z98qiRISzCE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=XeIMpTocNtZtvepFG9wj1I1V11yjloABKHA1+ncNL2sQFdsaNV7bFe4mGr55kaRcWDOpXzJYDqUhsKXVAdfxAbhZXqrwuvj6t7MkjmUewPpVjhTAjzb9f6dYmOd7DUURT1HFB8cg6eMiS5GN9cA+Lkt/dRo6WlZb9zwwNAg26h0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=WtV6lqu0; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="WtV6lqu0" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 595A9C116C6; Mon, 9 Feb 2026 14:39:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1770647997; bh=f0MbFLYMpQD4rYbvDBKJG1X4IFZvRGh+z98qiRISzCE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=WtV6lqu0jMqXBRplu4Nyqyr0VFIsWozTMGASfzmWvPzpIzR/xsgmoarZbDpMY0tbt 9bacig95vIrxc2xSPKtEQ/CVI6uilTsH/ZdM0E4D8baoA1fg7URz4Kt7A+rtyfoxrz mGzPPvMPzV8p7rmVJXWkGlTCbuVBkvkaCWCJ6fDc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Eric Dumazet , valis , syzbot+7182fbe91e58602ec1fe@syzkaller.appspotmail.com, Boudewijn van der Heide , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.12 090/113] macvlan: fix error recovery in macvlan_common_newlink() Date: Mon, 9 Feb 2026 15:23:59 +0100 Message-ID: <20260209142313.417305107@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260209142310.204833231@linuxfoundation.org> References: <20260209142310.204833231@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet [ Upstream commit f8db6475a83649689c087a8f52486fcc53e627e9 ] valis provided a nice repro to crash the kernel: ip link add p1 type veth peer p2 ip link set address 00:00:00:00:00:20 dev p1 ip link set up dev p1 ip link set up dev p2 ip link add mv0 link p2 type macvlan mode source ip link add invalid% link p2 type macvlan mode source macaddr add 00:00:00:00:00:20 ping -c1 -I p1 1.2.3.4 He also gave a very detailed analysis: The issue is triggered when a new macvlan link is created with MACVLAN_MODE_SOURCE mode and MACVLAN_MACADDR_ADD (or MACVLAN_MACADDR_SET) parameter, lower device already has a macvlan port and register_netdevice() called from macvlan_common_newlink() fails (e.g. because of the invalid link name). In this case macvlan_hash_add_source is called from macvlan_change_sources() / macvlan_common_newlink(): This adds a reference to vlan to the port's vlan_source_hash using macvlan_source_entry. vlan is a pointer to the priv data of the link that is being created. When register_netdevice() fails, the error is returned from macvlan_newlink() to rtnl_newlink_create(): if (ops->newlink) err = ops->newlink(dev, ¶ms, extack); else err = register_netdevice(dev); if (err < 0) { free_netdev(dev); goto out; } and free_netdev() is called, causing a kvfree() on the struct net_device that is still referenced in the source entry attached to the lower device's macvlan port. Now all packets sent on the macvlan port with a matching source mac address will trigger a use-after-free in macvlan_forward_source(). With all that, my fix is to make sure we call macvlan_flush_sources() regardless of @create value whenever "goto destroy_macvlan_port;" path is taken. Many thanks to valis for following up on this issue. Fixes: aa5fd0fb7748 ("driver: macvlan: Destroy new macvlan port if macvlan_common_newlink failed.") Signed-off-by: Eric Dumazet Reported-by: valis Reported-by: syzbot+7182fbe91e58602ec1fe@syzkaller.appspotmail.com Closes: https: //lore.kernel.org/netdev/695fb1e8.050a0220.1c677c.039f.GAE@google.com/T/#u Cc: Boudewijn van der Heide Link: https://patch.msgid.link/20260129204359.632556-1-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- drivers/net/macvlan.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c index ee59b57dfb53a..aaf7d755fc8a1 100644 --- a/drivers/net/macvlan.c +++ b/drivers/net/macvlan.c @@ -1563,9 +1563,10 @@ int macvlan_common_newlink(struct net *src_net, struct net_device *dev, /* the macvlan port may be freed by macvlan_uninit when fail to register. * so we destroy the macvlan port only when it's valid. */ - if (create && macvlan_port_get_rtnl(lowerdev)) { + if (macvlan_port_get_rtnl(lowerdev)) { macvlan_flush_sources(port, vlan); - macvlan_port_destroy(port->dev); + if (create) + macvlan_port_destroy(port->dev); } return err; } -- 2.51.0