From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37077) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XF81u-0006NP-IX for qemu-devel@nongnu.org; Wed, 06 Aug 2014 16:41:58 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XF81m-0004U9-QT for qemu-devel@nongnu.org; Wed, 06 Aug 2014 16:41:50 -0400 Received: from e9.ny.us.ibm.com ([32.97.182.139]:38952) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XF81m-0004Ty-Lo for qemu-devel@nongnu.org; Wed, 06 Aug 2014 16:41:42 -0400 Received: from /spool/local by e9.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 6 Aug 2014 16:41:42 -0400 From: Michael Roth Date: Wed, 6 Aug 2014 15:38:29 -0500 Message-Id: <1407357598-21541-20-git-send-email-mdroth@linux.vnet.ibm.com> In-Reply-To: <1407357598-21541-1-git-send-email-mdroth@linux.vnet.ibm.com> References: <1407357598-21541-1-git-send-email-mdroth@linux.vnet.ibm.com> Subject: [Qemu-devel] [PATCH 019/108] 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: qemu-stable@nongnu.org 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 (cherry picked from commit ead7a57df37d2187813a121308213f41591bd811) Signed-off-by: Michael Roth --- 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); -- 1.9.1