Revision 0447378a4a793da008451fad50bc0f93e9675ae6 authored by Marc Orr on 21 June 2018, 00:21:29 UTC, committed by Radim Krčmář on 22 June 2018, 14:46:26 UTC
This patch extends the checks done prior to a nested VM entry. Specifically, it extends the check_vmentry_prereqs function with checks for fields relevant to the VM-entry event injection information, as described in the Intel SDM, volume 3. This patch is motivated by a syzkaller bug, where a bad VM-entry interruption information field is generated in the VMCS02, which causes the nested VM launch to fail. Then, KVM fails to resume L1. While KVM should be improved to correctly resume L1 execution after a failed nested launch, this change is justified because the existing code to resume L1 is flaky/ad-hoc and the test coverage for resuming L1 is sparse. Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: Marc Orr <marcorr@google.com> [Removed comment whose parts were describing previous revisions and the rest was obvious from function/variable naming. - Radim] Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
1 parent 5f9077c
test_kprobes.c
/*
* test_kprobes.c - simple sanity test for *probes
*
* Copyright IBM Corp. 2008
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it would be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
* the GNU General Public License for more details.
*/
#define pr_fmt(fmt) "Kprobe smoke test: " fmt
#include <linux/kernel.h>
#include <linux/kprobes.h>
#include <linux/random.h>
#define div_factor 3
static u32 rand1, preh_val, posth_val;
static int errors, handler_errors, num_tests;
static u32 (*target)(u32 value);
static u32 (*target2)(u32 value);
static noinline u32 kprobe_target(u32 value)
{
return (value / div_factor);
}
static int kp_pre_handler(struct kprobe *p, struct pt_regs *regs)
{
if (preemptible()) {
handler_errors++;
pr_err("pre-handler is preemptible\n");
}
preh_val = (rand1 / div_factor);
return 0;
}
static void kp_post_handler(struct kprobe *p, struct pt_regs *regs,
unsigned long flags)
{
if (preemptible()) {
handler_errors++;
pr_err("post-handler is preemptible\n");
}
if (preh_val != (rand1 / div_factor)) {
handler_errors++;
pr_err("incorrect value in post_handler\n");
}
posth_val = preh_val + div_factor;
}
static struct kprobe kp = {
.symbol_name = "kprobe_target",
.pre_handler = kp_pre_handler,
.post_handler = kp_post_handler
};
static int test_kprobe(void)
{
int ret;
ret = register_kprobe(&kp);
if (ret < 0) {
pr_err("register_kprobe returned %d\n", ret);
return ret;
}
ret = target(rand1);
unregister_kprobe(&kp);
if (preh_val == 0) {
pr_err("kprobe pre_handler not called\n");
handler_errors++;
}
if (posth_val == 0) {
pr_err("kprobe post_handler not called\n");
handler_errors++;
}
return 0;
}
static noinline u32 kprobe_target2(u32 value)
{
return (value / div_factor) + 1;
}
static int kp_pre_handler2(struct kprobe *p, struct pt_regs *regs)
{
preh_val = (rand1 / div_factor) + 1;
return 0;
}
static void kp_post_handler2(struct kprobe *p, struct pt_regs *regs,
unsigned long flags)
{
if (preh_val != (rand1 / div_factor) + 1) {
handler_errors++;
pr_err("incorrect value in post_handler2\n");
}
posth_val = preh_val + div_factor;
}
static struct kprobe kp2 = {
.symbol_name = "kprobe_target2",
.pre_handler = kp_pre_handler2,
.post_handler = kp_post_handler2
};
static int test_kprobes(void)
{
int ret;
struct kprobe *kps[2] = {&kp, &kp2};
/* addr and flags should be cleard for reusing kprobe. */
kp.addr = NULL;
kp.flags = 0;
ret = register_kprobes(kps, 2);
if (ret < 0) {
pr_err("register_kprobes returned %d\n", ret);
return ret;
}
preh_val = 0;
posth_val = 0;
ret = target(rand1);
if (preh_val == 0) {
pr_err("kprobe pre_handler not called\n");
handler_errors++;
}
if (posth_val == 0) {
pr_err("kprobe post_handler not called\n");
handler_errors++;
}
preh_val = 0;
posth_val = 0;
ret = target2(rand1);
if (preh_val == 0) {
pr_err("kprobe pre_handler2 not called\n");
handler_errors++;
}
if (posth_val == 0) {
pr_err("kprobe post_handler2 not called\n");
handler_errors++;
}
unregister_kprobes(kps, 2);
return 0;
}
#if 0
static u32 jph_val;
static u32 j_kprobe_target(u32 value)
{
if (preemptible()) {
handler_errors++;
pr_err("jprobe-handler is preemptible\n");
}
if (value != rand1) {
handler_errors++;
pr_err("incorrect value in jprobe handler\n");
}
jph_val = rand1;
jprobe_return();
return 0;
}
static struct jprobe jp = {
.entry = j_kprobe_target,
.kp.symbol_name = "kprobe_target"
};
static int test_jprobe(void)
{
int ret;
ret = register_jprobe(&jp);
if (ret < 0) {
pr_err("register_jprobe returned %d\n", ret);
return ret;
}
ret = target(rand1);
unregister_jprobe(&jp);
if (jph_val == 0) {
pr_err("jprobe handler not called\n");
handler_errors++;
}
return 0;
}
static struct jprobe jp2 = {
.entry = j_kprobe_target,
.kp.symbol_name = "kprobe_target2"
};
static int test_jprobes(void)
{
int ret;
struct jprobe *jps[2] = {&jp, &jp2};
/* addr and flags should be cleard for reusing kprobe. */
jp.kp.addr = NULL;
jp.kp.flags = 0;
ret = register_jprobes(jps, 2);
if (ret < 0) {
pr_err("register_jprobes returned %d\n", ret);
return ret;
}
jph_val = 0;
ret = target(rand1);
if (jph_val == 0) {
pr_err("jprobe handler not called\n");
handler_errors++;
}
jph_val = 0;
ret = target2(rand1);
if (jph_val == 0) {
pr_err("jprobe handler2 not called\n");
handler_errors++;
}
unregister_jprobes(jps, 2);
return 0;
}
#else
#define test_jprobe() (0)
#define test_jprobes() (0)
#endif
#ifdef CONFIG_KRETPROBES
static u32 krph_val;
static int entry_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
{
if (preemptible()) {
handler_errors++;
pr_err("kretprobe entry handler is preemptible\n");
}
krph_val = (rand1 / div_factor);
return 0;
}
static int return_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
{
unsigned long ret = regs_return_value(regs);
if (preemptible()) {
handler_errors++;
pr_err("kretprobe return handler is preemptible\n");
}
if (ret != (rand1 / div_factor)) {
handler_errors++;
pr_err("incorrect value in kretprobe handler\n");
}
if (krph_val == 0) {
handler_errors++;
pr_err("call to kretprobe entry handler failed\n");
}
krph_val = rand1;
return 0;
}
static struct kretprobe rp = {
.handler = return_handler,
.entry_handler = entry_handler,
.kp.symbol_name = "kprobe_target"
};
static int test_kretprobe(void)
{
int ret;
ret = register_kretprobe(&rp);
if (ret < 0) {
pr_err("register_kretprobe returned %d\n", ret);
return ret;
}
ret = target(rand1);
unregister_kretprobe(&rp);
if (krph_val != rand1) {
pr_err("kretprobe handler not called\n");
handler_errors++;
}
return 0;
}
static int return_handler2(struct kretprobe_instance *ri, struct pt_regs *regs)
{
unsigned long ret = regs_return_value(regs);
if (ret != (rand1 / div_factor) + 1) {
handler_errors++;
pr_err("incorrect value in kretprobe handler2\n");
}
if (krph_val == 0) {
handler_errors++;
pr_err("call to kretprobe entry handler failed\n");
}
krph_val = rand1;
return 0;
}
static struct kretprobe rp2 = {
.handler = return_handler2,
.entry_handler = entry_handler,
.kp.symbol_name = "kprobe_target2"
};
static int test_kretprobes(void)
{
int ret;
struct kretprobe *rps[2] = {&rp, &rp2};
/* addr and flags should be cleard for reusing kprobe. */
rp.kp.addr = NULL;
rp.kp.flags = 0;
ret = register_kretprobes(rps, 2);
if (ret < 0) {
pr_err("register_kretprobe returned %d\n", ret);
return ret;
}
krph_val = 0;
ret = target(rand1);
if (krph_val != rand1) {
pr_err("kretprobe handler not called\n");
handler_errors++;
}
krph_val = 0;
ret = target2(rand1);
if (krph_val != rand1) {
pr_err("kretprobe handler2 not called\n");
handler_errors++;
}
unregister_kretprobes(rps, 2);
return 0;
}
#endif /* CONFIG_KRETPROBES */
int init_test_probes(void)
{
int ret;
target = kprobe_target;
target2 = kprobe_target2;
do {
rand1 = prandom_u32();
} while (rand1 <= div_factor);
pr_info("started\n");
num_tests++;
ret = test_kprobe();
if (ret < 0)
errors++;
num_tests++;
ret = test_kprobes();
if (ret < 0)
errors++;
num_tests++;
ret = test_jprobe();
if (ret < 0)
errors++;
num_tests++;
ret = test_jprobes();
if (ret < 0)
errors++;
#ifdef CONFIG_KRETPROBES
num_tests++;
ret = test_kretprobe();
if (ret < 0)
errors++;
num_tests++;
ret = test_kretprobes();
if (ret < 0)
errors++;
#endif /* CONFIG_KRETPROBES */
if (errors)
pr_err("BUG: %d out of %d tests failed\n", errors, num_tests);
else if (handler_errors)
pr_err("BUG: %d error(s) running handlers\n", handler_errors);
else
pr_info("passed successfully\n");
return 0;
}
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