From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:47510) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WVkrc-0006JE-DW for qemu-devel@nongnu.org; Thu, 03 Apr 2014 12:51:47 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WVkrW-0005i9-8t for qemu-devel@nongnu.org; Thu, 03 Apr 2014 12:51:40 -0400 Date: Thu, 3 Apr 2014 19:52:05 +0300 From: "Michael S. Tsirkin" Message-ID: <1396543778-22307-19-git-send-email-mst@redhat.com> References: <1396543778-22307-1-git-send-email-mst@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1396543778-22307-1-git-send-email-mst@redhat.com> Subject: [Qemu-devel] [PATCH v5 18/24] ssd0323: fix buffer overun on invalid state load List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Peter Maydell , Peter Crosthwaite , mdroth@linux.vnet.ibm.com, qemu-stable@nongnu.org, dgilbert@redhat.com, Gerd Hoffmann , Paolo Bonzini , =?us-ascii?B?PT9VVEYtOD9xP0FuZHJlYXM9MjBGPUMzPUE0cmJlcj89?= CVE-2013-4538 s->cmd_len used as index in ssd0323_transfer() to store 32-bit field. Possible this field might then be supplied by guest to overwrite a return addr somewhere. Same for row/col fields, which are indicies into framebuffer array. To fix validate after load. Additionally, validate that the row/col_start/end are within bounds; otherwise the guest can provoke an overrun by either setting the _end field so large that the row++ increments just walk off the end of the array, or by setting the _start value to something bogus and then letting the "we hit end of row" logic reset row to row_start. For completeness, validate mode as well. Signed-off-by: Michael S. Tsirkin --- hw/display/ssd0323.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/hw/display/ssd0323.c b/hw/display/ssd0323.c index 971152e..d4b9ea3 100644 --- a/hw/display/ssd0323.c +++ b/hw/display/ssd0323.c @@ -312,18 +312,42 @@ static int ssd0323_load(QEMUFile *f, void *opaque, int version_id) return -EINVAL; s->cmd_len = qemu_get_be32(f); + if (s->cmd_len < 0 || s->cmd_len > ARRAY_SIZE(s->cmd_data)) { + return -EINVAL; + } s->cmd = qemu_get_be32(f); for (i = 0; i < 8; i++) s->cmd_data[i] = qemu_get_be32(f); s->row = qemu_get_be32(f); + if (s->row < 0 || s->row >= 80 ) { + return -EINVAL; + } s->row_start = qemu_get_be32(f); + if (s->row_start < 0 || s->row_start >= 80 ) { + return -EINVAL; + } s->row_end = qemu_get_be32(f); + if (s->row_end < 0 || s->row_end >= 80 ) { + return -EINVAL; + } s->col = qemu_get_be32(f); + if (s->col < 0 || s->col >= 64 ) { + return -EINVAL; + } s->col_start = qemu_get_be32(f); + if (s->col_start < 0 || s->col_start >= 64 ) { + return -EINVAL; + } s->col_end = qemu_get_be32(f); + if (s->col_end < 0 || s->col_end >= 64 ) { + return -EINVAL; + } s->redraw = qemu_get_be32(f); s->remap = qemu_get_be32(f); s->mode = qemu_get_be32(f); + if (s->mode != SSD0323_CMD && s->mode != SSD0323_DATA) { + return -EINVAL; + } qemu_get_buffer(f, s->framebuffer, sizeof(s->framebuffer)); ss->cs = qemu_get_be32(f); -- MST