From 0cbd8c5754d6f56b53717e92353772777a799b87 Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Thu, 3 Apr 2014 19:52:05 +0300 Subject: [PATCH] ssd0323: fix buffer overun on invalid state load 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) --- 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);