From 4e1bfbe3a0a113fe3cf39336a9d7da4e8c2a21ea Mon Sep 17 00:00:00 2001 From: Jon Maloy Date: Mon, 5 Dec 2022 15:32:55 -0500 Subject: [PATCH 4/5] hw/display/qxl: Avoid buffer overrun in qxl_phys2virt (CVE-2022-4144) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit RH-Author: Jon Maloy RH-MergeRequest: 240: hw/display/qxl: Have qxl_log_command Return early if no log_cmd handler RH-Bugzilla: 2148545 RH-Acked-by: Gerd Hoffmann RH-Acked-by: Stefan Hajnoczi RH-Acked-by: Marc-André Lureau RH-Commit: [4/5] afe53f8d9b31c6fd8211fe172173151f3255e67c (jmaloy/jons-qemu-kvm) BZ: https://bugzilla.redhat.com/show_bug.cgi?id=2148545 CVE: CVE-2022-4144 Upstream: Merged commit 6dbbf055148c6f1b7d8a3251a65bd6f3d1e1f622 Author: Philippe Mathieu-Daudé Date: Mon Nov 28 21:27:40 2022 +0100 hw/display/qxl: Avoid buffer overrun in qxl_phys2virt (CVE-2022-4144) Have qxl_get_check_slot_offset() return false if the requested buffer size does not fit within the slot memory region. Similarly qxl_phys2virt() now returns NULL in such case, and qxl_dirty_one_surface() aborts. This avoids buffer overrun in the host pointer returned by memory_region_get_ram_ptr(). Fixes: CVE-2022-4144 (out-of-bounds read) Reported-by: Wenxu Yin (@awxylitol) Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1336 Signed-off-by: Philippe Mathieu-Daudé Signed-off-by: Stefan Hajnoczi Message-Id: <20221128202741.4945-5-philmd@linaro.org> (cherry picked from commit 6dbbf055148c6f1b7d8a3251a65bd6f3d1e1f622) Signed-off-by: Jon Maloy --- hw/display/qxl.c | 27 +++++++++++++++++++++++---- hw/display/qxl.h | 2 +- 2 files changed, 24 insertions(+), 5 deletions(-) diff --git a/hw/display/qxl.c b/hw/display/qxl.c index aa9065183e..2a4b2d4158 100644 --- a/hw/display/qxl.c +++ b/hw/display/qxl.c @@ -1412,11 +1412,13 @@ static void qxl_reset_surfaces(PCIQXLDevice *d) /* can be also called from spice server thread context */ static bool qxl_get_check_slot_offset(PCIQXLDevice *qxl, QXLPHYSICAL pqxl, - uint32_t *s, uint64_t *o) + uint32_t *s, uint64_t *o, + size_t size_requested) { uint64_t phys = le64_to_cpu(pqxl); uint32_t slot = (phys >> (64 - 8)) & 0xff; uint64_t offset = phys & 0xffffffffffff; + uint64_t size_available; if (slot >= NUM_MEMSLOTS) { qxl_set_guest_bug(qxl, "slot too large %d >= %d", slot, @@ -1440,6 +1442,23 @@ static bool qxl_get_check_slot_offset(PCIQXLDevice *qxl, QXLPHYSICAL pqxl, slot, offset, qxl->guest_slots[slot].size); return false; } + size_available = memory_region_size(qxl->guest_slots[slot].mr); + if (qxl->guest_slots[slot].offset + offset >= size_available) { + qxl_set_guest_bug(qxl, + "slot %d offset %"PRIu64" > region size %"PRIu64"\n", + slot, qxl->guest_slots[slot].offset + offset, + size_available); + return false; + } + size_available -= qxl->guest_slots[slot].offset + offset; + if (size_requested > size_available) { + qxl_set_guest_bug(qxl, + "slot %d offset %"PRIu64" size %zu: " + "overrun by %"PRIu64" bytes\n", + slot, offset, size_requested, + size_requested - size_available); + return false; + } *s = slot; *o = offset; @@ -1459,7 +1478,7 @@ void *qxl_phys2virt(PCIQXLDevice *qxl, QXLPHYSICAL pqxl, int group_id, offset = le64_to_cpu(pqxl) & 0xffffffffffff; return (void *)(intptr_t)offset; case MEMSLOT_GROUP_GUEST: - if (!qxl_get_check_slot_offset(qxl, pqxl, &slot, &offset)) { + if (!qxl_get_check_slot_offset(qxl, pqxl, &slot, &offset, size)) { return NULL; } ptr = memory_region_get_ram_ptr(qxl->guest_slots[slot].mr); @@ -1925,9 +1944,9 @@ static void qxl_dirty_one_surface(PCIQXLDevice *qxl, QXLPHYSICAL pqxl, uint32_t slot; bool rc; - rc = qxl_get_check_slot_offset(qxl, pqxl, &slot, &offset); - assert(rc == true); size = (uint64_t)height * abs(stride); + rc = qxl_get_check_slot_offset(qxl, pqxl, &slot, &offset, size); + assert(rc == true); trace_qxl_surfaces_dirty(qxl->id, offset, size); qxl_set_dirty(qxl->guest_slots[slot].mr, qxl->guest_slots[slot].offset + offset, diff --git a/hw/display/qxl.h b/hw/display/qxl.h index c784315daa..89ca832cf9 100644 --- a/hw/display/qxl.h +++ b/hw/display/qxl.h @@ -157,7 +157,7 @@ OBJECT_DECLARE_SIMPLE_TYPE(PCIQXLDevice, PCI_QXL) * * Returns a host pointer to a buffer placed at offset @phys within the * active slot @group_id of the PCI VGA RAM memory region associated with - * the @qxl device. If the slot is inactive, or the offset is out + * the @qxl device. If the slot is inactive, or the offset + size are out * of the memory region, returns NULL. * * Use with care; by the time this function returns, the returned pointer is -- 2.37.3