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From 27d5bab00da6a59c9eae2e5f66dc985f1a0b95ac Mon Sep 17 00:00:00 2001
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From: Gerd Hoffmann <kraxel@redhat.com>
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Date: Mon, 15 Sep 2014 13:08:23 +0200
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Subject: [PATCH 4/4] spice: make sure we don't overflow ssd->buf
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Message-id: <1410786503-19794-5-git-send-email-kraxel@redhat.com>
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Patchwork-id: 61136
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O-Subject: [RHEL-7.1 qemu-kvm PATCH 4/4] spice: make sure we don't overflow ssd->buf
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Bugzilla: 1139118
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RH-Acked-by: Markus Armbruster <armbru@redhat.com>
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RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
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RH-Acked-by: Laszlo Ersek <lersek@redhat.com>
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Related spice-only bug. We have a fixed 16 MB buffer here, being
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presented to the spice-server as qxl video memory in case spice is
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used with a non-qxl card. It's also used with qxl in vga mode.
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When using display resolutions requiring more than 16 MB of memory we
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are going to overflow that buffer. In theory the guest can write,
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indirectly via spice-server. The spice-server clears the memory after
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setting a new video mode though, triggering a segfault in the overflow
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case, so qemu crashes before the guest has a chance to do something
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evil.
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Fix that by switching to dynamic allocation for the buffer.
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CVE-2014-3615
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Cc: qemu-stable@nongnu.org
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Cc: secalert@redhat.com
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Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
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Reviewed-by: Laszlo Ersek <lersek@redhat.com>
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(cherry picked from commit ab9509cceabef28071e41bdfa073083859c949a7)
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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ui/spice-display.c | 20 +++++++++++++++-----
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1 files changed, 15 insertions(+), 5 deletions(-)
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diff --git a/ui/spice-display.c b/ui/spice-display.c
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index 5d0a21e..dc8be8a 100644
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--- a/ui/spice-display.c
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+++ b/ui/spice-display.c
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@@ -291,11 +291,23 @@ void qemu_spice_create_host_memslot(SimpleSpiceDisplay *ssd)
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void qemu_spice_create_host_primary(SimpleSpiceDisplay *ssd)
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{
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QXLDevSurfaceCreate surface;
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+ uint64_t surface_size;
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memset(&surface, 0, sizeof(surface));
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- dprint(1, "%s/%d: %dx%d\n", __func__, ssd->qxl.id,
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- surface_width(ssd->ds), surface_height(ssd->ds));
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+ surface_size = (uint64_t) surface_width(ssd->ds) *
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+ surface_height(ssd->ds) * 4;
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+ assert(surface_size > 0);
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+ assert(surface_size < INT_MAX);
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+ if (ssd->bufsize < surface_size) {
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+ ssd->bufsize = surface_size;
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+ g_free(ssd->buf);
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+ ssd->buf = g_malloc(ssd->bufsize);
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+ }
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+
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+ dprint(1, "%s/%d: %ux%u (size %" PRIu64 "/%d)\n", __func__, ssd->qxl.id,
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+ surface_width(ssd->ds), surface_height(ssd->ds),
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+ surface_size, ssd->bufsize);
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surface.format = SPICE_SURFACE_FMT_32_xRGB;
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surface.width = surface_width(ssd->ds);
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@@ -326,8 +338,6 @@ void qemu_spice_display_init_common(SimpleSpiceDisplay *ssd)
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if (ssd->num_surfaces == 0) {
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ssd->num_surfaces = 1024;
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}
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- ssd->bufsize = (16 * 1024 * 1024);
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- ssd->buf = g_malloc(ssd->bufsize);
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}
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/* display listener callbacks */
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@@ -446,7 +456,7 @@ static void interface_get_init_info(QXLInstance *sin, QXLDevInitInfo *info)
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info->num_memslots = NUM_MEMSLOTS;
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info->num_memslots_groups = NUM_MEMSLOTS_GROUPS;
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info->internal_groupslot_id = 0;
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- info->qxl_ram_size = ssd->bufsize;
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+ info->qxl_ram_size = 16 * 1024 * 1024;
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info->n_surfaces = ssd->num_surfaces;
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}
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--
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1.7.1
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