Fix CVE-2019-3813
Fix off-by-one error during guest-to-host memory address conversion Resolves: CVE-2019-3813
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Christophe Fergeau
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5e7b62fa49
commit
d8d79a1fe1
@ -0,0 +1,98 @@
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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Christophe Fergeau <cfergeau@redhat.com>
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Date: Thu, 29 Nov 2018 14:18:39 +0100
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Subject: [PATCH] memslot: Fix off-by-one error in group/slot boundary check
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RedMemSlotInfo keeps an array of groups, and each group contains an
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array of slots. Unfortunately, these checks are off by 1, they check
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that the index is greater or equal to the number of elements in the
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array, while these arrays are 0 based. The check should only check for
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strictly greater than the number of elements.
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For the group array, this is not a big issue, as these memslot groups
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are created by spice-server users (eg QEMU), and the group ids used to
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index that array are also generated by the spice-server user, so it
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should not be possible for the guest to set them to arbitrary values.
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The slot id is more problematic, as it's calculated from a QXLPHYSICAL
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address, and such addresses are usually set by the guest QXL driver, so
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the guest can set these to arbitrary values, including malicious values,
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which are probably easy to build from the guest PCI configuration.
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This patch fixes the arrays bound check, and adds a test case for this.
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This fixes CVE-2019-3813.
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Signed-off-by: Christophe Fergeau <cfergeau@redhat.com>
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---
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server/memslot.c | 4 ++--
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server/tests/test-qxl-parsing.c | 30 ++++++++++++++++++++++++++++++
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2 files changed, 32 insertions(+), 2 deletions(-)
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diff --git a/server/memslot.c b/server/memslot.c
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index ede77e7..ea6f981 100644
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--- a/server/memslot.c
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+++ b/server/memslot.c
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@@ -97,13 +97,13 @@ void *memslot_get_virt(RedMemSlotInfo *info, QXLPHYSICAL addr, uint32_t add_size
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MemSlot *slot;
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- if (group_id > info->num_memslots_groups) {
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+ if (group_id >= info->num_memslots_groups) {
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spice_critical("group_id too big");
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return NULL;
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}
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slot_id = memslot_get_id(info, addr);
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- if (slot_id > info->num_memslots) {
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+ if (slot_id >= info->num_memslots) {
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print_memslots(info);
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spice_critical("slot_id %d too big, addr=%" PRIx64, slot_id, addr);
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return NULL;
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diff --git a/server/tests/test-qxl-parsing.c b/server/tests/test-qxl-parsing.c
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index 47139a4..5b8d0f2 100644
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--- a/server/tests/test-qxl-parsing.c
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+++ b/server/tests/test-qxl-parsing.c
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@@ -85,6 +85,31 @@ static void deinit_qxl_surface(QXLSurfaceCmd *qxl)
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g_free(from_physical(qxl->u.surface_create.data));
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}
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+static void test_memslot_invalid_group_id(void)
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+{
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+ RedMemSlotInfo mem_info;
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+ init_meminfo(&mem_info);
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+
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+ memslot_get_virt(&mem_info, 0, 16, 1);
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+}
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+
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+static void test_memslot_invalid_slot_id(void)
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+{
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+ RedMemSlotInfo mem_info;
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+ init_meminfo(&mem_info);
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+
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+ memslot_get_virt(&mem_info, 1 << mem_info.memslot_id_shift, 16, 0);
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+}
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+
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+static void test_memslot_invalid_addresses(void)
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+{
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+ g_test_trap_subprocess("/server/memslot-invalid-addresses/subprocess/group_id", 0, 0);
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+ g_test_trap_assert_stderr("*group_id too big*");
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+
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+ g_test_trap_subprocess("/server/memslot-invalid-addresses/subprocess/slot_id", 0, 0);
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+ g_test_trap_assert_stderr("*slot_id 1 too big*");
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+}
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+
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static void test_no_issues(void)
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{
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RedMemSlotInfo mem_info;
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@@ -262,6 +287,11 @@ int main(int argc, char *argv[])
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{
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g_test_init(&argc, &argv, NULL);
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+ /* try to use invalid memslot group/slot */
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+ g_test_add_func("/server/memslot-invalid-addresses", test_memslot_invalid_addresses);
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+ g_test_add_func("/server/memslot-invalid-addresses/subprocess/group_id", test_memslot_invalid_group_id);
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+ g_test_add_func("/server/memslot-invalid-addresses/subprocess/slot_id", test_memslot_invalid_slot_id);
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+
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/* try to create a surface with no issues, should succeed */
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g_test_add_func("/server/qxl-parsing-no-issues", test_no_issues);
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@ -1,12 +1,13 @@
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Name: spice
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Version: 0.14.1
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Release: 2%{?dist}
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Release: 3%{?dist}
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Summary: Implements the SPICE protocol
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License: LGPLv2+
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URL: http://www.spice-space.org/
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Source0: http://www.spice-space.org/download/releases/%{name}-%{version}.tar.bz2
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Source1: http://www.spice-space.org/download/releases/%{name}-%{version}.tar.bz2.sign
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Source2: cfergeau-29AC6C82.keyring
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Patch1: 0001-memslot-Fix-off-by-one-error-in-group-slot-boundary-.patch
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# https://bugzilla.redhat.com/show_bug.cgi?id=613529
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%if 0%{?rhel} && 0%{?rhel} <= 7
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@ -96,6 +97,10 @@ mkdir -p %{buildroot}%{_libexecdir}
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%changelog
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* Tue Feb 05 2019 Christophe Fergeau <cfergeau@redhat.com> - 0.14.1-3
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- Fix off-by-one error during guest-to-host memory address conversion
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Resolves: CVE-2019-3813
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* Sun Feb 03 2019 Fedora Release Engineering <releng@fedoraproject.org> - 0.14.1-2
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- Rebuilt for https://fedoraproject.org/wiki/Fedora_30_Mass_Rebuild
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