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[88.187.86.199]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-486fe8359acsm291324285e9.12.2026.03.23.09.54.06 for (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Mon, 23 Mar 2026 09:54:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1774284847; x=1774889647; darn=nongnu.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:to:from:from:to:cc:subject:date:message-id :reply-to; bh=HxZq9kuwV2EPeGqBtGUjPbFp7Ne2hS6lS30xXSScbwA=; b=csI/04/qSKUKg5FwMqNBgKpRQOIt/rcyspTGnH4kA7xfqz2s5ro9d8FXasMZUinQIg I06n+9oQ9r33vs55m9Ng41p6CIKu8igpaWcHiCb5Ete6Vf2M0qRKVunq+GdQPfzsEZHW p6bnzK1TcZ+F0wORfsWBfJXDq6ohD4Q0p10FgBiuH9X+qWSSdbrxfvaHkt5JW9iVShV1 Foph4Ojv9oGy1U2O4ECXPvF+hNn1l/rQNPMFtIW6IMNw3FvQ9EUYJCZiZF1WM2HwgWct TlPXebjvlZf/FcPxcLGfBYWycRYriJypmSlFv1AKLVQ+19G01UMge93q8qSArMstgJid 1bFw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1774284847; x=1774889647; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:to:from:x-gm-gg:x-gm-message-state:from:to :cc:subject:date:message-id:reply-to; bh=HxZq9kuwV2EPeGqBtGUjPbFp7Ne2hS6lS30xXSScbwA=; b=KulkaDcD/bGqsENVsrbNEWP/OZFvbThqv8UdaAjSM3JBbduD6DawCoFdoW+K4+S035 /6xZogBw1dl4L06HQM6LyfsPc6J4tM1C57qgSml0cV5ogF55kuuhsxXftB1KYWDEgx1q GPswKyR/Sa/e2/9fEtQlHW1LLd+QsMvVK1TJCBz2ex4mRgIhKXMt4kjJ8rSVgQhUQ19t w5FOI8F54YFsOd49YcDXKAx/Rl2C+P6WXBt/rWJAAOd81drtPbAO/074uVAoeavI1LX3 4sFwb2rOulH+2ntSgIqro2S+aJ4mXxBSHpjhYuA/vKCVLYQHEOswMFV2ENEO9qXst4oc nq8A== X-Gm-Message-State: AOJu0Yx4PYUGbH1D4cYTFXpRqRfIi6fGloRWS84ve25wgkgCAzJ06AKM +a5oidwVLxdoANMISr5GviiqBG5lYGK8WJiJPhELoJqwAxHYMDuhbBlFfFBubNshihzHc+HzgJk t4wCeJH0= X-Gm-Gg: ATEYQzxn3nlQL10QRJqHI1/ynvLgPvFHB2G23GduXxPAub72M2CxzLC+KNTVeidiNRx 7owDMc8ZdGvknKwXJUBTwJHRuxsyOuKLU5w7osjmDpysRB29yvSfYpFouJPoqvzr+AvlZqAzBYs fJo1XTpFAvue0rJNsTN3ym7oHUlY/CwFYgMTFYXiFn/iqm/vn2u4MsSa/bZEj/xSJNCh/SClI+F 7IVbq6Pa7UyLMMiqvzbRImpvhzy926QWURdkwvhPR5NGALMIbZFqjZs0tymolpNfV13x0Flno1g bl6rjdVVFZEblsbPSyM1ebl4/KOT1tQ18XyQZcKgIhneSB1uvpYiaIbQ74ygcz/iXfKhCBdbZRZ OAIQFmIuwh3cCfChrS0qkrafKFWZSo8+Yjd0ghKiFZM5+e5UiFJml8cZSla25H0icK0jGrrjLCV 2A1/1NPa9g+GNydzxuJJx8HVIoqH8g6Hd13fU/BGQfpgfPdGjnpQ0oNhVGggbKmeUrR3h/IVMOT KEA9Vv5T1E= X-Received: by 2002:a05:600c:3546:b0:486:fbdb:b718 with SMTP id 5b1f17b1804b1-486fee29536mr182910175e9.25.1774284847005; Mon, 23 Mar 2026 09:54:07 -0700 (PDT) From: =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= To: qemu-devel@nongnu.org Subject: [PULL 16/27] hw/usb/hcd-ohci: check for MPS=0 to avoid infinite loop Date: Mon, 23 Mar 2026 17:52:07 +0100 Message-ID: <20260323165218.96607-17-philmd@linaro.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260323165218.96607-1-philmd@linaro.org> References: <20260323165218.96607-1-philmd@linaro.org> 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=2a00:1450:4864:20::32b; envelope-from=philmd@linaro.org; helo=mail-wm1-x32b.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, 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: qemu development 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-ZohoMail-DKIM: pass (identity @linaro.org) X-ZM-MESSAGEID: 1774284873076158500 From: Jenny Guanni Qu When a guest sets MaxPacketSize to 0 in an OHCI Endpoint Descriptor, ohci_service_td() transfers 0 bytes per iteration. The Transfer Descriptor never completes because CBP never advances toward BE, causing ohci_service_ed_list() to loop indefinitely and hang QEMU. Add a check for MPS=3D=3D0 after extracting the field from ED flags. If MPS is zero, call ohci_die() to reset the controller and return an error, preventing the infinite loop. Fixes: CVE-2026-3890 Reported-by: Jenny Guanni Qu Signed-off-by: Jenny Guanni Qu Reviewed-by: Peter Maydell Message-ID: <20260321000444.909451-1-qguanni@gmail.com> Signed-off-by: Philippe Mathieu-Daud=C3=A9 --- hw/usb/hcd-ohci.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/hw/usb/hcd-ohci.c b/hw/usb/hcd-ohci.c index 1aeed9286f5..6ed8046fc20 100644 --- a/hw/usb/hcd-ohci.c +++ b/hw/usb/hcd-ohci.c @@ -956,6 +956,17 @@ static int ohci_service_td(OHCIState *ohci, struct ohc= i_ed *ed) if (len && dir !=3D OHCI_TD_DIR_IN) { /* The endpoint may not allow us to transfer it all now */ pktlen =3D (ed->flags & OHCI_ED_MPS_MASK) >> OHCI_ED_MPS_SHIFT; + /* + * The OHCI spec does not say what to do if the guest hands us + * an endpoint descriptor which specifies a MaximumPacketSize + * of zero, which would mean we can never actually make forward + * progress transferring data to it. We choose to treat it as + * an error. + */ + if (pktlen =3D=3D 0) { + ohci_die(ohci); + return 1; + } if (pktlen > len) { pktlen =3D len; } --=20 2.53.0