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Fri, 28 Aug 2020 08:08:52 +0000 (UTC) Received: from sirius.home.kraxel.org (ovpn-112-54.ams2.redhat.com [10.36.112.54]) by smtp.corp.redhat.com (Postfix) with ESMTP id 711B17A21E; Fri, 28 Aug 2020 08:08:52 +0000 (UTC) Received: by sirius.home.kraxel.org (Postfix, from userid 1000) id 95C5F31FC5; Fri, 28 Aug 2020 10:08:46 +0200 (CEST) From: Gerd Hoffmann To: qemu-devel@nongnu.org Subject: [PULL 18/18] usb: fix setup_len init (CVE-2020-14364) Date: Fri, 28 Aug 2020 10:08:45 +0200 Message-Id: <20200828080845.28287-19-kraxel@redhat.com> In-Reply-To: <20200828080845.28287-1-kraxel@redhat.com> References: <20200828080845.28287-1-kraxel@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=kraxel@redhat.com X-Mimecast-Spam-Score: 0.001 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=207.211.31.81; envelope-from=kraxel@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/08/28 01:02:42 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.959, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=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: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: =?utf-8?q?Daniel_P=2E_Berrang=C3=A9?= , Eduardo Habkost , Li Qiang , Gonglei , Gerd Hoffmann , Cleber Rosa , Paolo Bonzini Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Store calculated setup_len in a local variable, verify it, and only write it to the struct (USBDevice->setup_len) in case it passed the sanity checks. This prevents other code (do_token_{in,out} functions specifically) from working with invalid USBDevice->setup_len values and overrunning the USBDevice->setup_buf[] buffer. Fixes: CVE-2020-14364 Signed-off-by: Gerd Hoffmann Tested-by: Gonglei Reviewed-by: Li Qiang Message-id: 20200825053636.29648-1-kraxel@redhat.com --- hw/usb/core.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) diff --git a/hw/usb/core.c b/hw/usb/core.c index 5abd128b6bc5..5234dcc73fea 100644 --- a/hw/usb/core.c +++ b/hw/usb/core.c @@ -129,6 +129,7 @@ void usb_wakeup(USBEndpoint *ep, unsigned int stream) static void do_token_setup(USBDevice *s, USBPacket *p) { int request, value, index; + unsigned int setup_len; if (p->iov.size != 8) { p->status = USB_RET_STALL; @@ -138,14 +139,15 @@ static void do_token_setup(USBDevice *s, USBPacket *p) usb_packet_copy(p, s->setup_buf, p->iov.size); s->setup_index = 0; p->actual_length = 0; - s->setup_len = (s->setup_buf[7] << 8) | s->setup_buf[6]; - if (s->setup_len > sizeof(s->data_buf)) { + setup_len = (s->setup_buf[7] << 8) | s->setup_buf[6]; + if (setup_len > sizeof(s->data_buf)) { fprintf(stderr, "usb_generic_handle_packet: ctrl buffer too small (%d > %zu)\n", - s->setup_len, sizeof(s->data_buf)); + setup_len, sizeof(s->data_buf)); p->status = USB_RET_STALL; return; } + s->setup_len = setup_len; request = (s->setup_buf[0] << 8) | s->setup_buf[1]; value = (s->setup_buf[3] << 8) | s->setup_buf[2]; @@ -259,26 +261,28 @@ static void do_token_out(USBDevice *s, USBPacket *p) static void do_parameter(USBDevice *s, USBPacket *p) { int i, request, value, index; + unsigned int setup_len; for (i = 0; i < 8; i++) { s->setup_buf[i] = p->parameter >> (i*8); } s->setup_state = SETUP_STATE_PARAM; - s->setup_len = (s->setup_buf[7] << 8) | s->setup_buf[6]; s->setup_index = 0; request = (s->setup_buf[0] << 8) | s->setup_buf[1]; value = (s->setup_buf[3] << 8) | s->setup_buf[2]; index = (s->setup_buf[5] << 8) | s->setup_buf[4]; - if (s->setup_len > sizeof(s->data_buf)) { + setup_len = (s->setup_buf[7] << 8) | s->setup_buf[6]; + if (setup_len > sizeof(s->data_buf)) { fprintf(stderr, "usb_generic_handle_packet: ctrl buffer too small (%d > %zu)\n", - s->setup_len, sizeof(s->data_buf)); + setup_len, sizeof(s->data_buf)); p->status = USB_RET_STALL; return; } + s->setup_len = setup_len; if (p->pid == USB_TOKEN_OUT) { usb_packet_copy(p, s->data_buf, s->setup_len);