PROBLEM: syzkaller found / pool corruption-overwrite / page in user-area or NULL

From: Esme
Date: Thu Jan 10 2019 - 14:12:28 EST

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Sorry for the resend some mail servers rejected the mime type.

Hi, I've been getting more into Kernel stuff lately and forged ahead with some syzkaller bug finding. I played with reducing it further as you can see from the attached c code but am moving on and hope to get better about this process moving forward as I'm still building out my test systems/debugging tools.

Attached is the report and C repro that still triggers on a fresh git pull as of a few minutes ago, if you need anything else please let me know.
Esme

Linux syzkaller 5.0.0-rc1+ #5 SMP Tue Jan 8 20:39:33 EST 2019 x86_64 GNU/Linux

GNU C 6.3.0
Binutils 2.28
Util-linux 2.29.2
Mount 2.29.2
Module-init-tools 23
E2fsprogs 1.43.4
Linux C Library 2.24
Dynamic linker (ldd) 2.24
Linux C++ Library 6.0.22
Procps 3.3.12
Sh-utils 8.26
Udev 232

// autogenerated by syzkaller (https://github.com/google/syzkaller)

#define _GNU_SOURCE

#include <dirent.h>
#include <endian.h>
#include <errno.h>
#include <fcntl.h>
#include <setjmp.h>
#include <signal.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/prctl.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <time.h>
#include <unistd.h>

#include <linux/genetlink.h>
#include <linux/netlink.h>

unsigned long long procid;

static __thread int skip_segv;
static __thread jmp_buf segv_env;

static void segv_handler(int sig, siginfo_t* info, void* ctx)
{
uintptr_t addr = (uintptr_t)info->si_addr;
const uintptr_t prog_start = 1 << 20;
const uintptr_t prog_end = 100 << 20;
if (__atomic_load_n(&skip_segv, __ATOMIC_RELAXED) && (addr < prog_start || addr > prog_end)) {
_longjmp(segv_env, 1);
}
exit(sig);
}

static void install_segv_handler(void)
{
struct sigaction sa;
memset(&sa, 0, sizeof(sa));
sa.sa_handler = SIG_IGN;
syscall(SYS_rt_sigaction, 0x20, &sa, NULL, 8);
syscall(SYS_rt_sigaction, 0x21, &sa, NULL, 8);
memset(&sa, 0, sizeof(sa));
sa.sa_sigaction = segv_handler;
sa.sa_flags = SA_NODEFER | SA_SIGINFO;
sigaction(SIGSEGV, &sa, NULL);
sigaction(SIGBUS, &sa, NULL);
}

#define NONFAILING(...) { __atomic_fetch_add(&skip_segv, 1, __ATOMIC_SEQ_CST); if (_setjmp(segv_env) == 0) { __VA_ARGS__; } __atomic_fetch_sub(&skip_segv, 1, __ATOMIC_SEQ_CST); }

static void sleep_ms(uint64_t ms)
{
usleep(ms * 1000);
}

static uint64_t current_time_ms(void)
{
struct timespec ts;
if (clock_gettime(CLOCK_MONOTONIC, &ts))
exit(1);
return (uint64_t)ts.tv_sec * 1000 + (uint64_t)ts.tv_nsec / 1000000;
}

static long syz_open_dev(long a0, long a1, long a2)
{
if (a0 == 0xc || a0 == 0xb) {
char buf[128];
sprintf(buf, "/dev/%s/%d:%d", a0 == 0xc ? "char" : "block", (uint8_t)a1, (uint8_t)a2);
return open(buf, O_RDWR, 0);
} else {
char buf[1024];
char* hash;
NONFAILING(strncpy(buf, (char*)a0, sizeof(buf) - 1));
buf[sizeof(buf) - 1] = 0;
while ((hash = strchr(buf, '#'))) {
*hash = '0' + (char)(a1 % 10);
a1 /= 10;
}
return open(buf, a2, 0);
}
}

static long syz_open_pts(long a0, long a1)
{
int ptyno = 0;
if (ioctl(a0, TIOCGPTN, &ptyno))
return -1;
char buf[128];
sprintf(buf, "/dev/pts/%d", ptyno);
return open(buf, a1, 0);
}

static long syz_genetlink_get_family_id(long name)
{
char buf[512] = {0};
struct nlmsghdr* hdr = (struct nlmsghdr*)buf;
struct genlmsghdr* genlhdr = (struct genlmsghdr*)NLMSG_DATA(hdr);
struct nlattr* attr = (struct nlattr*)(genlhdr + 1);
hdr->nlmsg_len = sizeof(*hdr) + sizeof(*genlhdr) + sizeof(*attr) + GENL_NAMSIZ;
hdr->nlmsg_type = GENL_ID_CTRL;
hdr->nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK;
genlhdr->cmd = CTRL_CMD_GETFAMILY;
attr->nla_type = CTRL_ATTR_FAMILY_NAME;
attr->nla_len = sizeof(*attr) + GENL_NAMSIZ;
NONFAILING(strncpy((char*)(attr + 1), (char*)name, GENL_NAMSIZ));
struct iovec iov = {hdr, hdr->nlmsg_len};
struct sockaddr_nl addr = {0};
addr.nl_family = AF_NETLINK;
int fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_GENERIC);
if (fd == -1) {
return -1;
}
struct msghdr msg = {&addr, sizeof(addr), &iov, 1, NULL, 0, 0};
if (sendmsg(fd, &msg, 0) == -1) {
close(fd);
return -1;
}
ssize_t n = recv(fd, buf, sizeof(buf), 0);
close(fd);
if (n <= 0) {
return -1;
}
if (hdr->nlmsg_type != GENL_ID_CTRL) {
return -1;
}
for (; (char*)attr < buf + n; attr = (struct nlattr*)((char*)attr + NLMSG_ALIGN(attr->nla_len))) {
if (attr->nla_type == CTRL_ATTR_FAMILY_ID)
return *(uint16_t*)(attr + 1);
}
return -1;
}

static void kill_and_wait(int pid, int* status)
{
kill(-pid, SIGKILL);
kill(pid, SIGKILL);
int i;
for (i = 0; i < 100; i++) {
if (waitpid(-1, status, WNOHANG | __WALL) == pid)
return;
usleep(1000);
}
DIR* dir = opendir("/sys/fs/fuse/connections");
if (dir) {
for (;;) {
struct dirent* ent = readdir(dir);
if (!ent)
break;
if (strcmp(ent->d_name, ".") == 0 || strcmp(ent->d_name, "..") == 0)
continue;
char abort[300];
snprintf(abort, sizeof(abort), "/sys/fs/fuse/connections/%s/abort", ent->d_name);
int fd = open(abort, O_WRONLY);
if (fd == -1) {
continue;
}
if (write(fd, abort, 1) < 0) {
}
close(fd);
}
closedir(dir);
} else {
}
while (waitpid(-1, status, __WALL) != pid) {
}
}

#define SYZ_HAVE_SETUP_TEST 1
static void setup_test()
{
prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0);
setpgrp();
}

#define SYZ_HAVE_RESET_TEST 1
static void reset_test()
{
int fd;
for (fd = 3; fd < 30; fd++)
close(fd);
}

static void execute_one(void);

#define WAIT_FLAGS __WALL

static void loop(void)
{
int iter;
for (iter = 0;; iter++) {
int pid = fork();
if (pid < 0)
exit(1);
if (pid == 0) {
setup_test();
execute_one();
reset_test();
exit(0);
}
int status = 0;
uint64_t start = current_time_ms();
for (;;) {
if (waitpid(-1, &status, WNOHANG | WAIT_FLAGS) == pid)
break;
sleep_ms(1);
if (current_time_ms() - start < 5 * 1000)
continue;
kill_and_wait(pid, &status);
break;
}
}
}

uint64_t r[2] = {0xffffffffffffffff, 0xffffffffffffffff};

void execute_one(void)
{
long res = 0;

NONFAILING(memcpy((void*)0x20000080, "/dev/sg#\x00", 9));
res = syz_open_dev(0x20000080, 0, 0);
if (res != -1)
r[0] = res;
syscall(__NR_socket, 0xc, 0x800, 0x88);
syscall(__NR_ioctl, 0xffffff9c, 0x8933, 0);
NONFAILING(*(uint32_t*)0x200000c0 = 1);
NONFAILING(*(uint32_t*)0x200000c4 = 0);
NONFAILING(*(uint32_t*)0x200000c8 = 8);
NONFAILING(memcpy((void*)0x200000cc, "\x86", 1));
syscall(__NR_ioctl, r[0], 1, 0x200000c0);
syscall(__NR_openat, -1, 0, 0x88400, 0x100);
syscall(__NR_socket, 0x11, 2, 0x300);
syscall(__NR_write, -1, 0, 0);
syscall(__NR_getsockopt, -1, 0x29, 0x39, 0, 0);
syscall(__NR_read, -1, 0, 0);
syscall(__NR_ioctl, -1, 0x5437, 0);
syz_genetlink_get_family_id(0);
syscall(__NR_getpid);
NONFAILING(memcpy((void*)0x20000000, "/dev/loop#\x00", 11));
syz_open_dev(0x20000000, 0, 0);
syz_open_dev(0, 2, 0x100);
syscall(__NR_socket, 0x11, 3, 0x300);
/*
NONFAILING(*(uint64_t*)0x200003c0 = 0x200002c0);
NONFAILING(*(uint16_t*)0x200002c0 = 0x10);
NONFAILING(*(uint16_t*)0x200002c2 = 0);
NONFAILING(*(uint32_t*)0x200002c4 = 0);
NONFAILING(*(uint32_t*)0x200002c8 = 2);
NONFAILING(*(uint32_t*)0x200003c8 = 0xc);
NONFAILING(*(uint64_t*)0x200003d0 = 0x20000380);
NONFAILING(*(uint64_t*)0x20000380 = 0);
NONFAILING(*(uint64_t*)0x20000388 = 0);
NONFAILING(*(uint64_t*)0x200003d8 = 1);
NONFAILING(*(uint64_t*)0x200003e0 = 0);
NONFAILING(*(uint64_t*)0x200003e8 = 0);
NONFAILING(*(uint32_t*)0x200003f0 = 1);
syscall(__NR_sendmsg, -1, 0x200003c0, 0x40040);
syscall(__NR_openat, 0xffffffffffffff9c, 0, 0, 0);
res = syscall(__NR_dup, -1);
if (res != -1)
r[1] = res;
syscall(__NR_ioctl, r[1], 0x8903, 0);
syscall(__NR_fdatasync, -1);
syscall(__NR_shmctl, 0, 3, 0);
syscall(__NR_openat, 0xffffffffffffff9c, 0, 0x20000, 0);
syscall(__NR_creat, 0, 0);
syscall(__NR_fcntl, -1, 4, 0x40003);
syscall(__NR_write, -1, 0, 0);
syscall(__NR_setitimer, 1, 0, 0);
syscall(__NR_inotify_add_watch, -1, 0, 0x24000004);
syscall(__NR_unlink, 0);
NONFAILING(*(uint32_t*)0x20000180 = 0);
NONFAILING(*(uint32_t*)0x20000184 = 0);
NONFAILING(*(uint32_t*)0x20000188 = 0);
NONFAILING(*(uint32_t*)0x2000018c = 0);
NONFAILING(*(uint32_t*)0x20000190 = 0);
NONFAILING(*(uint32_t*)0x20000194 = 0);
syscall(__NR_capset, 0, 0x20000180);
NONFAILING(*(uint64_t*)0x20000100 = 0);
NONFAILING(*(uint64_t*)0x20000108 = 0);
syscall(__NR_vmsplice, -1, 0x20000100, 1, 0);
syscall(__NR_ioctl, -1, 0x89e0, 0);
syscall(__NR_socket, 0xa, 2, 0);
syscall(__NR_pipe2, 0, 0x84800);
syscall(__NR_pipe, 0);
*/
syz_open_pts(0xffffff9c, 0x80000);
syscall(__NR_socket, 0xa, 3, 0x3a);
syscall(__NR_getsockopt, 0xffffff9c, 0x29, 0x22, 0, 0);
syscall(__NR_readv, -1, 0, 0);
syscall(__NR_creat, 0, 0);
syscall(__NR_connect, -1, 0, 0);
syscall(__NR_setsockopt, -1, 1, 0x19, 0, 0);
syscall(__NR_sendmsg, -1, 0, 0x10);
syscall(__NR_socket, 0x10, 3, 0x10);
syscall(__NR_socket, 0x10, 3, 6);
syscall(__NR_openat, 0xffffffffffffff9c, 0, 0x440040, 0);
syscall(__NR_openat, 0xffffffffffffff9c, 0, 0x8000, 0);
syscall(__NR_mmap, 0x20ff7000, 0x9000, 0, 0x5811, -1, 0);
syscall(__NR_fstat, -1, 0);
syscall(__NR_ioctl, -1, 0x40247007, 0);
syscall(__NR_openat, 0xffffffffffffff9c, 0, 0x801, 0);
syscall(__NR_ioctl, -1, 0x891b, 0);
syscall(__NR_ioctl, -1, 0x541c, 0);
syscall(__NR_openat, 0xffffffffffffff9c, 0, 0x200002, 0);
syscall(__NR_socket, 2, 2, 0x88);
syscall(__NR_readv, -1, 0, 0);
syscall(__NR_pipe2, 0x20000000, 0);

}
int main(void)
{
syscall(__NR_mmap, 0x20000000, 0x1000000, 3, 0x32, -1, 0);
install_segv_handler();
for (procid = 0; procid < 8; procid++) {
if (fork() == 0) {
loop();
}
}
sleep(1000000);
return 0;
}

Attachment: repro.report
Description: Binary data

Next message: Greg KH: "Re: [PATCH 2/2] x86/selftests/pkeys: fork() to check for state being preserved"
Previous message: gregkh@xxxxxxxxxxxxxxxxxxx: "Re: [4.9 PATCH] MIPS: math-emu: Write-protect delay slot emulation pages"
Next in thread: James Bottomley: "Re: PROBLEM: syzkaller found / pool corruption-overwrite / page in user-area or NULL"
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