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From:   xingwei lee <xrivendell7@gmail.com>
Date:   Wed, 22 Nov 2023 14:13:36 +0800
Message-ID: <CABOYnLyY40dS4p2beHyEnXqSm4K_NuXAvsozOvz=cX9TnxXsYA@mail.gmail.com>
Subject: Re: [syzbot] [kernel?] KASAN: slab-use-after-free Read in kill_orphaned_pgrp
To:     "syzbot+50ef815ba3bcce06d409@syzkaller.appspotmail.com" 
        <syzbot+50ef815ba3bcce06d409@syzkaller.appspotmail.com>
Cc:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "luto@kernel.org" <luto@kernel.org>,
        "peterz@infradead.org" <peterz@infradead.org>,
        "syzkaller-bugs@googlegroups.com" <syzkaller-bugs@googlegroups.com>,
        "tglx@linutronix.de" <tglx@linutronix.de>
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Precedence: bulk

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;

}