108 lines
4.5 KiB
Diff
108 lines
4.5 KiB
Diff
From 0c4e22da6bd0d2c15e53cb0b38f13ef11a3bd370 Mon Sep 17 00:00:00 2001
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From: jianchunfu <jianchunfu_yewu@cmss.chinamobile.com>
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Date: Mon, 5 Dec 2022 16:24:43 +0800
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Subject: [PATCH 16/17] hw/display/qxl: Avoid buffer overrun in qxl_phys2virt
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(CVE-2022-4144)
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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Have qxl_get_check_slot_offset() return false if the requested
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buffer size does not fit within the slot memory region.
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Similarly qxl_phys2virt() now returns NULL in such case, and
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qxl_dirty_one_surface() aborts.
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This avoids buffer overrun in the host pointer returned by
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memory_region_get_ram_ptr().
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Fixes: CVE-2022-4144 (out-of-bounds read)
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Reported-by: Wenxu Yin (@awxylitol)
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Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1336
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Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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Signed-off-by: jianchunfu <jianchunfu_yewu@cmss.chinamobile.com>
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---
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hw/display/qxl.c | 27 +++++++++++++++++++++++----
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hw/display/qxl.h | 2 +-
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2 files changed, 24 insertions(+), 5 deletions(-)
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diff --git a/hw/display/qxl.c b/hw/display/qxl.c
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index aa9065183e..2a4b2d4158 100644
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--- a/hw/display/qxl.c
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+++ b/hw/display/qxl.c
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@@ -1412,11 +1412,13 @@ static void qxl_reset_surfaces(PCIQXLDevice *d)
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/* can be also called from spice server thread context */
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static bool qxl_get_check_slot_offset(PCIQXLDevice *qxl, QXLPHYSICAL pqxl,
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- uint32_t *s, uint64_t *o)
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+ uint32_t *s, uint64_t *o,
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+ size_t size_requested)
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{
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uint64_t phys = le64_to_cpu(pqxl);
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uint32_t slot = (phys >> (64 - 8)) & 0xff;
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uint64_t offset = phys & 0xffffffffffff;
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+ uint64_t size_available;
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if (slot >= NUM_MEMSLOTS) {
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qxl_set_guest_bug(qxl, "slot too large %d >= %d", slot,
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@@ -1440,6 +1442,23 @@ static bool qxl_get_check_slot_offset(PCIQXLDevice *qxl, QXLPHYSICAL pqxl,
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slot, offset, qxl->guest_slots[slot].size);
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return false;
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}
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+ size_available = memory_region_size(qxl->guest_slots[slot].mr);
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+ if (qxl->guest_slots[slot].offset + offset >= size_available) {
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+ qxl_set_guest_bug(qxl,
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+ "slot %d offset %"PRIu64" > region size %"PRIu64"\n",
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+ slot, qxl->guest_slots[slot].offset + offset,
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+ size_available);
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+ return false;
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+ }
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+ size_available -= qxl->guest_slots[slot].offset + offset;
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+ if (size_requested > size_available) {
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+ qxl_set_guest_bug(qxl,
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+ "slot %d offset %"PRIu64" size %zu: "
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+ "overrun by %"PRIu64" bytes\n",
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+ slot, offset, size_requested,
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+ size_requested - size_available);
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+ return false;
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+ }
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*s = slot;
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*o = offset;
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@@ -1459,7 +1478,7 @@ void *qxl_phys2virt(PCIQXLDevice *qxl, QXLPHYSICAL pqxl, int group_id,
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offset = le64_to_cpu(pqxl) & 0xffffffffffff;
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return (void *)(intptr_t)offset;
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case MEMSLOT_GROUP_GUEST:
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- if (!qxl_get_check_slot_offset(qxl, pqxl, &slot, &offset)) {
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+ if (!qxl_get_check_slot_offset(qxl, pqxl, &slot, &offset, size)) {
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return NULL;
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}
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ptr = memory_region_get_ram_ptr(qxl->guest_slots[slot].mr);
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@@ -1925,9 +1944,9 @@ static void qxl_dirty_one_surface(PCIQXLDevice *qxl, QXLPHYSICAL pqxl,
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uint32_t slot;
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bool rc;
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- rc = qxl_get_check_slot_offset(qxl, pqxl, &slot, &offset);
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- assert(rc == true);
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size = (uint64_t)height * abs(stride);
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+ rc = qxl_get_check_slot_offset(qxl, pqxl, &slot, &offset, size);
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+ assert(rc == true);
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trace_qxl_surfaces_dirty(qxl->id, offset, size);
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qxl_set_dirty(qxl->guest_slots[slot].mr,
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qxl->guest_slots[slot].offset + offset,
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diff --git a/hw/display/qxl.h b/hw/display/qxl.h
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index c784315daa..89ca832cf9 100644
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--- a/hw/display/qxl.h
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+++ b/hw/display/qxl.h
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@@ -157,7 +157,7 @@ OBJECT_DECLARE_SIMPLE_TYPE(PCIQXLDevice, PCI_QXL)
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*
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* Returns a host pointer to a buffer placed at offset @phys within the
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* active slot @group_id of the PCI VGA RAM memory region associated with
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- * the @qxl device. If the slot is inactive, or the offset is out
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+ * the @qxl device. If the slot is inactive, or the offset + size are out
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* of the memory region, returns NULL.
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*
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* Use with care; by the time this function returns, the returned pointer is
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--
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2.27.0
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