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Thu, 04 Jun 2020 05:11:18 -0400 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-492-8LwWd-mXNFCNngYWrOw6eg-1; Thu, 04 Jun 2020 05:11:12 -0400 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 79DEC835B8B; Thu, 4 Jun 2020 09:11:11 +0000 (UTC) Received: from localhost.localdomain (ovpn-116-200.sin2.redhat.com [10.67.116.200]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 0FC9A19C58; Thu, 4 Jun 2020 09:11:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1591261876; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=lqPlpcY1f7um6lZyFEQekaUFS+zb2uLYGtmAfm4q6Ek=; b=NeqkTt8Y6DICvoh3mx8KXyVgutBKTFcifRpqzuxB4XVCpV6MTNmVZ1gafHQt01Sq+Ib52y MQck8EEkppHWHXswMyyCgxzk8N9tN1E2IGenXl/+jfdmA5krEUugkYh9W2CeIASZqeO6dY IE2kPvIdtOxh7h33ld/ohU0v8/jMnCE= X-MC-Unique: 8LwWd-mXNFCNngYWrOw6eg-1 From: P J P To: Gerd Hoffmann Subject: [PATCH v3] ati-vga: check mm_index before recursive call (CVE-2020-13800) Date: Thu, 4 Jun 2020 14:38:30 +0530 Message-Id: <20200604090830.33885-1-ppandit@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com 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=205.139.110.61; envelope-from=ppandit@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/06/04 01:08:38 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] 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, DKIMWL_WL_HIGH=0.001, 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_H2=-0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN 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=20P=20=2E=20Berrang=C3=A9?= , Prasad J Pandit , Yi Ren , QEMU Developers , Ren Ding , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , Hanqing Zhao Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) From: Prasad J Pandit While accessing VGA registers via ati_mm_read/write routines, a guest may set 's->regs.mm_index' such that it leads to infinite recursion. Check mm_index value to avoid such recursion. Log an error message for wrong values. Reported-by: Ren Ding Reported-by: Hanqing Zhao Reported-by: Yi Ren Suggested-by: BALATON Zoltan Suggested-by: Philippe Mathieu-Daud=C3=A9 Signed-off-by: Prasad J Pandit --- hw/display/ati.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) Update v3: log error message -> https://lists.gnu.org/archive/html/qemu-devel/2020-06/msg00827.html diff --git a/hw/display/ati.c b/hw/display/ati.c index 60c5f246fd..98c21e7bd5 100644 --- a/hw/display/ati.c +++ b/hw/display/ati.c @@ -285,8 +285,11 @@ static uint64_t ati_mm_read(void *opaque, hwaddr addr,= unsigned int size) if (idx <=3D s->vga.vram_size - size) { val =3D ldn_le_p(s->vga.vram_ptr + idx, size); } - } else { + } else if (s->regs.mm_index > MM_DATA + 3) { val =3D ati_mm_read(s, s->regs.mm_index + addr - MM_DATA, size= ); + } else { + qemu_log_mask(LOG_GUEST_ERROR, + "ati_mm_read: mm_index too small: %u\n", s->regs.mm_index); } break; case BIOS_0_SCRATCH ... BUS_CNTL - 1: @@ -523,8 +526,11 @@ static void ati_mm_write(void *opaque, hwaddr addr, if (idx <=3D s->vga.vram_size - size) { stn_le_p(s->vga.vram_ptr + idx, size, data); } - } else { + } else if (s->regs.mm_index > MM_DATA + 3) { ati_mm_write(s, s->regs.mm_index + addr - MM_DATA, data, size); + } else { + qemu_log_mask(LOG_GUEST_ERROR, + "ati_mm_write: mm_index too small: %u\n", s->regs.mm_index= ); } break; case BIOS_0_SCRATCH ... BUS_CNTL - 1: --=20 2.26.2