From nobody Tue Feb 10 07:22:31 2026 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1763785177780801.1105174403973; Fri, 21 Nov 2025 20:19:37 -0800 (PST) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1vMdCt-0002S1-BL; Fri, 21 Nov 2025 21:18:36 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vMd8U-00066M-JN; Fri, 21 Nov 2025 21:14:02 -0500 Received: from isrv.corpit.ru ([212.248.84.144]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vMd7j-0004wT-U7; Fri, 21 Nov 2025 21:13:58 -0500 Received: from tsrv.corpit.ru (tsrv.tls.msk.ru [192.168.177.2]) by isrv.corpit.ru (Postfix) with ESMTP id 6BF5216C70D; Fri, 21 Nov 2025 16:51:58 +0300 (MSK) Received: from think4mjt.tls.msk.ru (mjtthink.wg.tls.msk.ru [192.168.177.146]) by tsrv.corpit.ru (Postfix) with ESMTP id C43BE3219AA; Fri, 21 Nov 2025 16:52:06 +0300 (MSK) From: Michael Tokarev To: qemu-devel@nongnu.org Cc: qemu-stable@nongnu.org, Peter Maydell , Akihiko Odaki , Jason Wang , Michael Tokarev Subject: [Stable-10.1.3 53/76] net: pad packets to minimum length in qemu_receive_packet() Date: Fri, 21 Nov 2025 16:51:31 +0300 Message-ID: <20251121135201.1114964-53-mjt@tls.msk.ru> X-Mailer: git-send-email 2.47.3 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=212.248.84.144; envelope-from=mjt@tls.msk.ru; helo=isrv.corpit.ru X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, T_SPF_HELO_TEMPERROR=0.01, T_SPF_TEMPERROR=0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZM-MESSAGEID: 1763785181368018900 Content-Type: text/plain; charset="utf-8" From: Peter Maydell In commits like 969e50b61a28 ("net: Pad short frames to minimum size before sending from SLiRP/TAP") we switched away from requiring network devices to handle short frames to instead having the net core code do the padding of short frames out to the ETH_ZLEN minimum size. We then dropped the code for handling short frames from the network devices in a series of commits like 140eae9c8f7 ("hw/net: e1000: Remove the logic of padding short frames in the receive path"). This missed one route where the device's receive code can still see a short frame: if the device is in loopback mode and it transmits a short frame via the qemu_receive_packet() function, this will be fed back into its own receive code without being padded. Add the padding logic to qemu_receive_packet(). This fixes a buffer overrun which can be triggered in the e1000_receive_iov() logic via the loopback code path. Other devices that use qemu_receive_packet() to implement loopback are cadence_gem, dp8393x, lan9118, msf2-emac, pcnet, rtl8139 and sungem. Cc: qemu-stable@nongnu.org Resolves: https://gitlab.com/qemu-project/qemu/-/issues/3043 Reviewed-by: Akihiko Odaki Signed-off-by: Peter Maydell Signed-off-by: Jason Wang (cherry picked from commit a01344d9d78089e9e585faaeb19afccff2050abf) Signed-off-by: Michael Tokarev diff --git a/net/net.c b/net/net.c index da275db86e..63fafb583b 100644 --- a/net/net.c +++ b/net/net.c @@ -766,10 +766,20 @@ ssize_t qemu_send_packet(NetClientState *nc, const ui= nt8_t *buf, int size) =20 ssize_t qemu_receive_packet(NetClientState *nc, const uint8_t *buf, int si= ze) { + uint8_t min_pkt[ETH_ZLEN]; + size_t min_pktsz =3D sizeof(min_pkt); + if (!qemu_can_receive_packet(nc)) { return 0; } =20 + if (net_peer_needs_padding(nc)) { + if (eth_pad_short_frame(min_pkt, &min_pktsz, buf, size)) { + buf =3D min_pkt; + size =3D min_pktsz; + } + } + return qemu_net_queue_receive(nc->incoming_queue, buf, size); } =20 --=20 2.47.3