From nobody Sun Feb 23 11:01:56 2025 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 1740160390774216.0145487551208; Fri, 21 Feb 2025 09:53:10 -0800 (PST) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1tlXAQ-00011c-9U; Fri, 21 Feb 2025 12:50:26 -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 1tlXAC-0000yO-4t; Fri, 21 Feb 2025 12:50:12 -0500 Received: from isrv.corpit.ru ([86.62.121.231]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tlXAA-0001pL-5V; Fri, 21 Feb 2025 12:50:11 -0500 Received: from tsrv.corpit.ru (tsrv.tls.msk.ru [192.168.177.2]) by isrv.corpit.ru (Postfix) with ESMTP id 4F00DEFB6D; Fri, 21 Feb 2025 20:49:31 +0300 (MSK) Received: from gandalf.tls.msk.ru (mjt.wg.tls.msk.ru [192.168.177.130]) by tsrv.corpit.ru (Postfix) with ESMTP id 07CD81BB589; Fri, 21 Feb 2025 20:49:51 +0300 (MSK) Received: by gandalf.tls.msk.ru (Postfix, from userid 1000) id E65A153F8D; Fri, 21 Feb 2025 20:49:50 +0300 (MSK) From: Michael Tokarev To: qemu-devel@nongnu.org Cc: qemu-stable@nongnu.org, Peter Maydell , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , Michael Tokarev Subject: [Stable-9.2.2 10/14] hw/net/smc91c111: Ignore attempt to pop from empty RX fifo Date: Fri, 21 Feb 2025 20:49:40 +0300 Message-Id: <20250221174949.836197-10-mjt@tls.msk.ru> X-Mailer: git-send-email 2.39.5 In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" 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=86.62.121.231; envelope-from=mjt@tls.msk.ru; helo=isrv.corpit.ru X-Spam_score_int: -68 X-Spam_score: -6.9 X-Spam_bar: ------ X-Spam_report: (-6.9 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_HI=-5, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 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: 1740160392902019100 From: Peter Maydell The SMC91C111 includes an MMU Command register which permits the guest to remove entries from the RX FIFO. The datasheet does not specify what happens if the guest tries to do this when the FIFO is already empty; there are no status registers containing error bits which might be applicable. Currently we don't guard at all against pop of an empty RX FIFO, with the result that we allow the guest to drive the rx_fifo_len index to negative values, which will cause smc91c111_receive() to write to the rx_fifo[] array out of bounds when we receive the next packet. Instead ignore attempts to pop an empty RX FIFO. Cc: qemu-stable@nongnu.org Fixes: 80337b66a8e7 ("NIC emulation for qemu arm-softmmu") Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2780 Signed-off-by: Peter Maydell Reviewed-by: Philippe Mathieu-Daud=C3=A9 Message-ID: <20250207151157.3151776-1-peter.maydell@linaro.org> Signed-off-by: Philippe Mathieu-Daud=C3=A9 (cherry picked from commit 937df81af6757638a7f1908747560dd342947213) Signed-off-by: Michael Tokarev diff --git a/hw/net/smc91c111.c b/hw/net/smc91c111.c index 180ba5c791..2a652885c9 100644 --- a/hw/net/smc91c111.c +++ b/hw/net/smc91c111.c @@ -182,6 +182,15 @@ static void smc91c111_pop_rx_fifo(smc91c111_state *s) { int i; =20 + if (s->rx_fifo_len =3D=3D 0) { + /* + * The datasheet doesn't document what the behaviour is if the + * guest tries to pop an empty RX FIFO, and there's no obvious + * error status register to report it. Just ignore the attempt. + */ + return; + } + s->rx_fifo_len--; if (s->rx_fifo_len) { for (i =3D 0; i < s->rx_fifo_len; i++) --=20 2.39.5