77 lines
2.5 KiB
Diff
77 lines
2.5 KiB
Diff
From: "Michael S. Tsirkin" <mst@redhat.com>
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Date: Thu, 3 Apr 2014 19:52:05 +0300
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Subject: [PATCH] ssd0323: fix buffer overun on invalid state load
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CVE-2013-4538
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s->cmd_len used as index in ssd0323_transfer() to store 32-bit field.
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Possible this field might then be supplied by guest to overwrite a
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return addr somewhere. Same for row/col fields, which are indicies into
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framebuffer array.
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To fix validate after load.
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Additionally, validate that the row/col_start/end are within bounds;
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otherwise the guest can provoke an overrun by either setting the _end
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field so large that the row++ increments just walk off the end of the
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array, or by setting the _start value to something bogus and then
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letting the "we hit end of row" logic reset row to row_start.
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For completeness, validate mode as well.
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Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
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Signed-off-by: Juan Quintela <quintela@redhat.com>
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(cherry picked from commit ead7a57df37d2187813a121308213f41591bd811)
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---
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hw/display/ssd0323.c | 24 ++++++++++++++++++++++++
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1 file changed, 24 insertions(+)
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diff --git a/hw/display/ssd0323.c b/hw/display/ssd0323.c
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index c3231c6..773414c 100644
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--- a/hw/display/ssd0323.c
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+++ b/hw/display/ssd0323.c
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@@ -312,18 +312,42 @@ static int ssd0323_load(QEMUFile *f, void *opaque, int version_id)
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return -EINVAL;
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s->cmd_len = qemu_get_be32(f);
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+ if (s->cmd_len < 0 || s->cmd_len > ARRAY_SIZE(s->cmd_data)) {
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+ return -EINVAL;
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+ }
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s->cmd = qemu_get_be32(f);
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for (i = 0; i < 8; i++)
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s->cmd_data[i] = qemu_get_be32(f);
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s->row = qemu_get_be32(f);
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+ if (s->row < 0 || s->row >= 80) {
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+ return -EINVAL;
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+ }
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s->row_start = qemu_get_be32(f);
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+ if (s->row_start < 0 || s->row_start >= 80) {
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+ return -EINVAL;
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+ }
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s->row_end = qemu_get_be32(f);
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+ if (s->row_end < 0 || s->row_end >= 80) {
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+ return -EINVAL;
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+ }
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s->col = qemu_get_be32(f);
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+ if (s->col < 0 || s->col >= 64) {
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+ return -EINVAL;
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+ }
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s->col_start = qemu_get_be32(f);
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+ if (s->col_start < 0 || s->col_start >= 64) {
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+ return -EINVAL;
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+ }
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s->col_end = qemu_get_be32(f);
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+ if (s->col_end < 0 || s->col_end >= 64) {
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+ return -EINVAL;
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+ }
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s->redraw = qemu_get_be32(f);
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s->remap = qemu_get_be32(f);
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s->mode = qemu_get_be32(f);
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+ if (s->mode != SSD0323_CMD && s->mode != SSD0323_DATA) {
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+ return -EINVAL;
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+ }
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qemu_get_buffer(f, s->framebuffer, sizeof(s->framebuffer));
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ss->cs = qemu_get_be32(f);
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