From 7e52a4f784fce9177952cd2e5e73de2bc4b23ddf Mon Sep 17 00:00:00 2001 Message-Id: <7e52a4f784fce9177952cd2e5e73de2bc4b23ddf.1427148003.git.jen@redhat.com> In-Reply-To: References: From: Gerd Hoffmann Date: Wed, 11 Mar 2015 15:11:03 -0500 Subject: [CHANGE 9/9] spice: make sure we don't overflow ssd->buf MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit To: rhvirt-patches@redhat.com, jen@redhat.com RH-Author: Gerd Hoffmann Message-id: <1426086663-17937-10-git-send-email-kraxel@redhat.com> Patchwork-id: 64287 O-Subject: [RHEL-6.7 qemu-kvm PATCH v4 9/9] spice: make sure we don't overflow ssd->buf Bugzilla: 1053039 RH-Acked-by: Dr. David Alan Gilbert RH-Acked-by: Marc-André Lureau RH-Acked-by: Laszlo Ersek Related spice-only bug. We have a fixed 16 MB buffer here, being presented to the spice-server as qxl video memory in case spice is used with a non-qxl card. It's also used with qxl in vga mode. When using display resolutions requiring more than 16 MB of memory we are going to overflow that buffer. In theory the guest can write, indirectly via spice-server. The spice-server clears the memory after setting a new video mode though, triggering a segfault in the overflow case, so qemu crashes before the guest has a chance to do something evil. Fix that by switching to dynamic allocation for the buffer. CVE-2014-3615 Cc: qemu-stable@nongnu.org Cc: secalert@redhat.com Signed-off-by: Gerd Hoffmann Reviewed-by: Laszlo Ersek (cherry picked from commit ab9509cceabef28071e41bdfa073083859c949a7) Signed-off-by: Jeff E. Nelson Conflicts: ui/spice-display.c --- ui/spice-display.c | 24 +++++++++++++++++------- 1 file changed, 17 insertions(+), 7 deletions(-) Signed-off-by: Jeff E. Nelson --- ui/spice-display.c | 24 +++++++++++++++++------- 1 file changed, 17 insertions(+), 7 deletions(-) diff --git a/ui/spice-display.c b/ui/spice-display.c index 80149fc..f2919f5 100644 --- a/ui/spice-display.c +++ b/ui/spice-display.c @@ -298,9 +298,23 @@ void qemu_spice_create_host_memslot(SimpleSpiceDisplay *ssd) void qemu_spice_create_host_primary(SimpleSpiceDisplay *ssd) { QXLDevSurfaceCreate surface; + uint64_t surface_size; - dprint(1, "%s: %dx%d\n", __FUNCTION__, - ds_get_width(ssd->ds), ds_get_height(ssd->ds)); + memset(&surface, 0, sizeof(surface)); + + surface_size = (uint64_t) ds_get_width(ssd->ds) * + ds_get_height(ssd->ds) * 4; + assert(surface_size > 0); + assert(surface_size < INT_MAX); + if (ssd->bufsize < surface_size) { + ssd->bufsize = surface_size; + g_free(ssd->buf); + ssd->buf = g_malloc(ssd->bufsize); + } + + dprint(1, "%s/%d: %ux%u (size %" PRIu64 "/%d)\n", __func__, ssd->qxl.id, + ds_get_width(ssd->ds), ds_get_height(ssd->ds), + surface_size, ssd->bufsize); surface.format = SPICE_SURFACE_FMT_32_xRGB; surface.width = ds_get_width(ssd->ds); @@ -329,8 +343,6 @@ void qemu_spice_display_init_common(SimpleSpiceDisplay *ssd, DisplayState *ds) QTAILQ_INIT(&ssd->updates); ssd->mouse_x = -1; ssd->mouse_y = -1; - ssd->bufsize = (16 * 1024 * 1024); - ssd->buf = qemu_malloc(ssd->bufsize); } /* display listener callbacks */ @@ -435,14 +447,12 @@ static void interface_set_mm_time(QXLInstance *sin, uint32_t mm_time) static void interface_get_init_info(QXLInstance *sin, QXLDevInitInfo *info) { - SimpleSpiceDisplay *ssd = container_of(sin, SimpleSpiceDisplay, qxl); - info->memslot_gen_bits = MEMSLOT_GENERATION_BITS; info->memslot_id_bits = MEMSLOT_SLOT_BITS; info->num_memslots = NUM_MEMSLOTS; info->num_memslots_groups = NUM_MEMSLOTS_GROUPS; info->internal_groupslot_id = 0; - info->qxl_ram_size = ssd->bufsize; + info->qxl_ram_size = 16 * 1024 * 1024; info->n_surfaces = NUM_SURFACES; } -- 2.1.0