From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 5E765395266; Tue, 21 Jul 2026 18:17:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784657829; cv=none; b=WWtacF/ZYUFyZ82Yabz1GSua1zFF3gjW5cZm+UAVW//qdoeYqbijJX4QpmE7soyKJC5ksUkksT4UAr+AoZWdnO7uJC99nN4REuf3dVr4qUyvLzVcWw0kYHOBUTyQhBcAlJWy8frFA50HbEMDO0q31uP2jZul1qJ2bT6IR1AAan8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784657829; c=relaxed/simple; bh=eATErBR4bNtSYW4bOR/JH6Ap5vCDNmMul+yV/Y3nDNI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=GyGHPWhGyx/JNo1M+5rKFym16+ocecYRRc6weLqFbD3uDysnkg7Fc1u+oTtEDTBFnj0oX6At1mPoLiIbYVPtq7z8NLRprXdooedosArc0HJ6N5y6VC5iK23YszVvxhBbSlUgYXsUu1RYGAfes8JVlLKt9Kovi/u6cbeBJ9eNbQo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=anIJAan5; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="anIJAan5" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C39A01F000E9; Tue, 21 Jul 2026 18:17:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784657828; bh=nPJWU6uDW/5/1T7vFr0BUfdubwsE8IV7wPymwVRpbSI=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=anIJAan5GtLvcnrm0OUh6IGBvWryZuMk2sn9YqMCMi7t0YUW/NS4L58+donTASgY2 6FBVSNdZhWAdlHav7OvCEY6NTfd48rFb9DfkQ/ZgI/X8KKnLLIK538UYEz8XfFFKpY jPVgLW53iobebs2d7JMjWIFzb1prIDJRgvbbpG+g= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Weiming Shi , Xiang Mei , Jiayuan Chen , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.18 0912/1611] net, bpf: check master for NULL in xdp_master_redirect() Date: Tue, 21 Jul 2026 17:17:08 +0200 Message-ID: <20260721152535.901103108@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152514.750365251@linuxfoundation.org> References: <20260721152514.750365251@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 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Xiang Mei [ Upstream commit e82d8cc4321c373dc46e741cd2dfdaa7921fddb7 ] xdp_master_redirect() dereferences the result of netdev_master_upper_dev_get_rcu() without a NULL check, but that helper returns NULL when the receiving device has no upper-master adjacency. The reach guard only checks netif_is_bond_slave(). On bond slave release bond_upper_dev_unlink() drops the upper-master adjacency before clearing IFF_SLAVE, so an XDP_TX reaching xdp_master_redirect() in that window still passes netif_is_bond_slave() while master is already NULL, and faults on master->flags at offset 0xb0: BUG: kernel NULL pointer dereference, address: 00000000000000b0 RIP: 0010:xdp_master_redirect (net/core/filter.c:4432) Call Trace: xdp_master_redirect (net/core/filter.c:4432) bpf_prog_run_generic_xdp (include/net/xdp.h:700) do_xdp_generic (net/core/dev.c:5608) __netif_receive_skb_one_core (net/core/dev.c:6204) process_backlog (net/core/dev.c:6319) __napi_poll (net/core/dev.c:7729) net_rx_action (net/core/dev.c:7792) handle_softirqs (kernel/softirq.c:622) __dev_queue_xmit (include/linux/bottom_half.h:33) packet_sendmsg (net/packet/af_packet.c:3082) __sys_sendto (net/socket.c:2252) Kernel panic - not syncing: Fatal exception in interrupt The missing check dates back to the original code; commit 1921f91298d1 ("net, bpf: fix null-ptr-deref in xdp_master_redirect() for down master") later added the master->flags read where the fault now lands but kept the unconditional deref. Check master for NULL before use; a NULL master is treated the same as one that is not up. Fixes: 879af96ffd72 ("net, core: Add support for XDP redirection to slave device") Reported-by: Weiming Shi Signed-off-by: Xiang Mei Reviewed-by: Jiayuan Chen Link: https://patch.msgid.link/20260620201531.180123-1-xmei5@asu.edu Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/core/filter.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/core/filter.c b/net/core/filter.c index a3e6cd9c4a78bc..42385e79043131 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -4424,7 +4424,7 @@ u32 xdp_master_redirect(struct xdp_buff *xdp) struct net_device *master, *slave; master = netdev_master_upper_dev_get_rcu(xdp->rxq->dev); - if (unlikely(!(master->flags & IFF_UP))) + if (unlikely(!master || !(master->flags & IFF_UP))) return XDP_ABORTED; slave = master->netdev_ops->ndo_xdp_get_xmit_slave(master, xdp); if (slave && slave != xdp->rxq->dev) { -- 2.53.0