From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:56630) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WhPXh-0007HE-RY for qemu-devel@nongnu.org; Mon, 05 May 2014 16:31:22 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WhPXa-0000wj-1K for qemu-devel@nongnu.org; Mon, 05 May 2014 16:31:17 -0400 Received: from mx1.redhat.com ([209.132.183.28]:25795) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WhPXZ-0000wY-Kh for qemu-devel@nongnu.org; Mon, 05 May 2014 16:31:09 -0400 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id s45KV8Cx002926 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Mon, 5 May 2014 16:31:09 -0400 From: Juan Quintela Date: Mon, 5 May 2014 22:30:13 +0200 Message-Id: <1399321834-31310-16-git-send-email-quintela@redhat.com> In-Reply-To: <1399321834-31310-1-git-send-email-quintela@redhat.com> References: <1399321834-31310-1-git-send-email-quintela@redhat.com> Subject: [Qemu-devel] [PATCH 15/36] 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: "Michael S. Tsirkin" From: "Michael S. Tsirkin" 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 Reviewed-by: Peter Maydell Signed-off-by: Juan Quintela --- hw/display/ssd0323.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/hw/display/ssd0323.c b/hw/display/ssd0323.c index 971152e..9727007 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); -- 1.9.0