Re: [syzbot] [kernel?] KASAN: slab-use-after-free Read in kill_orphaned_pgrp

From: xingwei lee
Date: Wed Nov 22 2023 - 01:13:53 EST

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In reply to: syzbot: "[syzbot] [kernel?] KASAN: slab-use-after-free Read in kill_orphaned_pgrp"
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Hi! I reproduce this bug.

Without analyzing deeply, I find the other bug titled "KASAN:
slab-use-after-free read in do_acct_process" or titled "KASAN:
slab-use-after-free in release_task" may also be the same because with
the same reproducer.

repro.txt

r0 = creat(&(0x7f0000000280)='./file0\x00', 0xecf86c37d53049cc)

write$binfmt_elf32(r0, &(0x7f0000000440)={{0x7f, 0x45, 0x4c, 0x46,
0x0, 0x0, 0x0, 0x0, 0x0, 0x2, 0x3e, 0x0, 0x0, 0x38, 0x0, 0x0, 0xeb0,
0x20, 0x2}, [{}], "", ['\x00', '\x00', '\x00', '\x00', '\x00', '\x00',
'\x00']}, 0x758)

close(r0)

r1 = openat$vnet(0xffffffffffffff9c, &(0x7f0000000000), 0x2, 0x0)

ioctl$int_in(r1, 0x40000000af01, 0x0)

execve(&(0x7f0000000400)='./file0\x00', 0x0, 0x0)

repro.c

#define _GNU_SOURCE

#include <dirent.h>

#include <endian.h>

#include <errno.h>

#include <fcntl.h>

#include <pthread.h>

#include <signal.h>

#include <stdarg.h>

#include <stdbool.h>

#include <stdint.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <sys/prctl.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/futex.h>

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 void thread_start(void* (*fn)(void*), void* arg)

{

pthread_t th;

pthread_attr_t attr;

pthread_attr_init(&attr);

pthread_attr_setstacksize(&attr, 128 << 10);

int i = 0;

for (; i < 100; i++) {

if (pthread_create(&th, &attr, fn, arg) == 0) {

pthread_attr_destroy(&attr);

return;

}

if (errno == EAGAIN) {

usleep(50);

continue;

}

break;

}

exit(1);

}

typedef struct {

int state;

} event_t;

static void event_init(event_t* ev)

{

ev->state = 0;

}

static void event_reset(event_t* ev)

{

ev->state = 0;

}

static void event_set(event_t* ev)

{

if (ev->state)

exit(1);

__atomic_store_n(&ev->state, 1, __ATOMIC_RELEASE);

syscall(SYS_futex, &ev->state, FUTEX_WAKE |
FUTEX_PRIVATE_FLAG, 1000000);

}

static void event_wait(event_t* ev)

{

while (!__atomic_load_n(&ev->state, __ATOMIC_ACQUIRE))

syscall(SYS_futex, &ev->state, FUTEX_WAIT |
FUTEX_PRIVATE_FLAG, 0, 0);

}

static int event_isset(event_t* ev)

{

return __atomic_load_n(&ev->state, __ATOMIC_ACQUIRE);

}

static int event_timedwait(event_t* ev, uint64_t timeout)

{

uint64_t start = current_time_ms();

uint64_t now = start;

for (;;) {

uint64_t remain = timeout - (now - start);

struct timespec ts;

ts.tv_sec = remain / 1000;

ts.tv_nsec = (remain % 1000) * 1000 * 1000;

syscall(SYS_futex, &ev->state, FUTEX_WAIT |
FUTEX_PRIVATE_FLAG, 0, &ts);

if (__atomic_load_n(&ev->state, __ATOMIC_ACQUIRE))

return 1;

now = current_time_ms();

if (now - start > timeout)

return 0;

}

}

static bool write_file(const char* file, const char* what, ...)

{

char buf[1024];

va_list args;

va_start(args, what);

vsnprintf(buf, sizeof(buf), what, args);

va_end(args);

buf[sizeof(buf) - 1] = 0;

int len = strlen(buf);

int fd = open(file, O_WRONLY | O_CLOEXEC);

if (fd == -1)

return false;

if (write(fd, buf, len) != len) {

int err = errno;

close(fd);

errno = err;

return false;

}

close(fd);

return true;

}

static void kill_and_wait(int pid, int* status)

{

kill(-pid, SIGKILL);

kill(pid, SIGKILL);

for (int 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) {

}

}

static void setup_test()

{

prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0);

setpgrp();

write_file("/proc/self/oom_score_adj", "1000");

}

struct thread_t {

int created, call;

event_t ready, done;

};

static struct thread_t threads[16];

static void execute_call(int call);

static int running;

static void* thr(void* arg)

{

struct thread_t* th = (struct thread_t*)arg;

for (;;) {

event_wait(&th->ready);

event_reset(&th->ready);

execute_call(th->call);

__atomic_fetch_sub(&running, 1, __ATOMIC_RELAXED);

event_set(&th->done);

}

return 0;

}

static void execute_one(void)

{

int i, call, thread;

for (call = 0; call < 6; call++) {

for (thread = 0; thread < (int)(sizeof(threads) /
sizeof(threads[0])); thread++) {

struct thread_t* th = &threads[thread];

if (!th->created) {

th->created = 1;

event_init(&th->ready);

event_init(&th->done);

event_set(&th->done);

thread_start(thr, th);

}

if (!event_isset(&th->done))

continue;

event_reset(&th->done);

th->call = call;

__atomic_fetch_add(&running, 1, __ATOMIC_RELAXED);

event_set(&th->ready);

event_timedwait(&th->done, 50);

break;

}

}

for (i = 0; i < 100 && __atomic_load_n(&running,
__ATOMIC_RELAXED); i++)

sleep_ms(1);

}

static void execute_one(void);

#define WAIT_FLAGS __WALL

static void loop(void)

{

int iter = 0;

for (;; iter++) {

int pid = fork();

if (pid < 0)

exit(1);

if (pid == 0) {

setup_test();

execute_one();

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 < 5000)

continue;

kill_and_wait(pid, &status);

break;

}

}

}

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

void execute_call(int call)

{

intptr_t res = 0;

switch (call) {

case 0:

memcpy((void*)0x20000280, "./file0\000", 8);

res = syscall(__NR_creat, /*file=*/0x20000280ul,
/*mode=*/0xecf86c37d53049ccul);

if (res != -1)

r[0] = res;

break;

case 1:

*(uint8_t*)0x20000440 = 0x7f;

*(uint8_t*)0x20000441 = 0x45;

*(uint8_t*)0x20000442 = 0x4c;

*(uint8_t*)0x20000443 = 0x46;

*(uint8_t*)0x20000444 = 0;

*(uint8_t*)0x20000445 = 0;

*(uint8_t*)0x20000446 = 0;

*(uint8_t*)0x20000447 = 0;

*(uint64_t*)0x20000448 = 0;

*(uint16_t*)0x20000450 = 2;

*(uint16_t*)0x20000452 = 0x3e;

*(uint32_t*)0x20000454 = 0;

*(uint32_t*)0x20000458 = 0;

*(uint32_t*)0x2000045c = 0x38;

*(uint32_t*)0x20000460 = 0;

*(uint32_t*)0x20000464 = 0;

*(uint16_t*)0x20000468 = 0xeb0;

*(uint16_t*)0x2000046a = 0x20;

*(uint16_t*)0x2000046c = 2;

*(uint16_t*)0x2000046e = 0;

*(uint16_t*)0x20000470 = 0;

*(uint16_t*)0x20000472 = 0;

*(uint32_t*)0x20000478 = 0;

*(uint32_t*)0x2000047c = 0;

*(uint32_t*)0x20000480 = 0;

*(uint32_t*)0x20000484 = 0;

*(uint32_t*)0x20000488 = 0;

*(uint32_t*)0x2000048c = 0;

*(uint32_t*)0x20000490 = 0;

*(uint32_t*)0x20000494 = 0;

memset((void*)0x20000498, 0, 256);

memset((void*)0x20000598, 0, 256);

memset((void*)0x20000698, 0, 256);

memset((void*)0x20000798, 0, 256);

memset((void*)0x20000898, 0, 256);

memset((void*)0x20000998, 0, 256);

memset((void*)0x20000a98, 0, 256);

syscall(__NR_write, /*fd=*/r[0],
/*data=*/0x20000440ul, /*len=*/0x758ul);

break;

case 2:

syscall(__NR_close, /*fd=*/r[0]);

break;

case 3:

memcpy((void*)0x20000000, "/dev/vhost-net\000", 15);

res = syscall(__NR_openat,
/*fd=*/0xffffffffffffff9cul, /*file=*/0x20000000ul, /*flags=*/2ul,
/*mode=*/0ul);

if (res != -1)

r[1] = res;

break;

case 4:

syscall(__NR_ioctl, /*fd=*/r[1], /*cmd=*/0xaf01, /*v=*/0ul);

break;

case 5:

memcpy((void*)0x20000400, "./file0\000", 8);

syscall(__NR_execve, /*file=*/0x20000400ul,
/*argv=*/0ul, /*envp=*/0ul);

break;

}

}

int main(void)

{

syscall(__NR_mmap, /*addr=*/0x1ffff000ul,
/*len=*/0x1000ul, /*prot=*/0ul, /*flags=*/0x32ul, /*fd=*/-1,
/*offset=*/0ul);

syscall(__NR_mmap, /*addr=*/0x20000000ul,
/*len=*/0x1000000ul, /*prot=*/7ul, /*flags=*/0x32ul, /*fd=*/-1,
/*offset=*/0ul);

syscall(__NR_mmap, /*addr=*/0x21000000ul, /*len=*/0x1000ul,
/*prot=*/0ul, /*flags=*/0x32ul, /*fd=*/-1, /*offset=*/0ul);

loop();

return 0;

}

Next message: Jason Wang: "Re: [PATCH v2 2/5] vduse: Add file operation for mmap"
Previous message: Kunwu Chan: "Re: [PATCH] ARM: imx: Check return value of devm_kasprintf in imx_mmdc_perf_init"
In reply to: syzbot: "[syzbot] [kernel?] KASAN: slab-use-after-free Read in kill_orphaned_pgrp"
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