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

[xingwei lee]

Hi. With my best effort, I have reproduced this bug with repro.c and repro.txt.

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

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

#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;
}

Without analyzing deeply, I find the other bug titled "KASAN: slab-use-after-free read in do_acct_process" may also be the same because with the same reproducer.
And when I test for this bug, it's also report the error like below:

[ 1062.533765][T86339] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1062.562117][T86342] file0[86342]: segfault at 0 ip 0000000000000000 sp 00000000ffb7a1f0 error 14 likely on CPU 0 (core 0, socket 0)
[ 1062.566368][T86342] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1062.598136][T86345] file0[86345]: segfault at 0 ip 0000000000000000 sp 00000000ffce6cc0 error 14 likely on CPU 0 (core 0, socket 0)
[ 1062.600713][T86345] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1062.660393][T86348] file0[86348]: segfault at 0 ip 0000000000000000 sp 00000000ffc1c260 error 14 likely on CPU 3 (core 3, socket 0)
[ 1062.661907][T86348] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1062.691681][T86351] file0[86351]: segfault at 0 ip 0000000000000000 sp 00000000ffc1dca0 error 14 likely on CPU 3 (core 3, socket 0)
[ 1062.695355][T86351] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1062.725966][T86354] file0[86354]: segfault at 0 ip 0000000000000000 sp 00000000ffd47680 error 14 likely on CPU 2 (core 2, socket 0)
[ 1062.730274][T86354] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1062.763794][T86357] file0[86357]: segfault at 0 ip 0000000000000000 sp 00000000ffb62ec0 error 14 likely on CPU 3 (core 3, socket 0)
[ 1062.767052][T86357] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1067.419025][T86748] show_signal_msg: 129 callbacks suppressed
[ 1067.419049][T86748] file0[86748]: segfault at 0 ip 0000000000000000 sp 00000000fff9cd60 error 14 likely on CPU 3 (core 3, socket 0)
[ 1067.423748][T86748] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1067.471776][T86751] file0[86751]: segfault at 0 ip 0000000000000000 sp 00000000ff9ef1b0 error 14 likely on CPU 3 (core 3, socket 0)
[ 1067.473511][T86751] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1067.507975][T86754] file0[86754]: segfault at 0 ip 0000000000000000 sp 00000000ff93a440 error 14 likely on CPU 2 (core 2, socket 0)
[ 1067.510922][T86754] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1067.539633][T86757] file0[86757]: segfault at 0 ip 0000000000000000 sp 00000000ffde4040 error 14 likely on CPU 3 (core 3, socket 0)
[ 1067.542672][T86757] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1067.569411][T86760] file0[86760]: segfault at 0 ip 0000000000000000 sp 00000000ff9a73f0 error 14 likely on CPU 3 (core 3, socket 0)
[ 1067.572216][T86760] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1067.602196][T86763] file0[86763]: segfault at 0 ip 0000000000000000 sp 00000000ffd94e30 error 14 likely on CPU 3 (core 3, socket 0)
[ 1067.606080][T86763] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1067.634806][T86766] file0[86766]: segfault at 0 ip 0000000000000000 sp 00000000ff9ad270 error 14 likely on CPU 3 (core 3, socket 0)
[ 1067.638389][T86766] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1067.665037][T86769] file0[86769]: segfault at 0 ip 0000000000000000 sp 00000000ff83ce40 error 14 likely on CPU 3 (core 3, socket 0)
[ 1067.668285][T86769] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1067.698637][T86772] file0[86772]: segfault at 0 ip 0000000000000000 sp 00000000ffebcaa0 error 14 likely on CPU 1 (core 1, socket 0)
[ 1067.701938][T86772] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1067.758462][T86775] file0[86775]: segfault at 0 ip 0000000000000000 sp 00000000ff904950 error 14 likely on CPU 2 (core 2, socket 0)
[ 1067.760315][T86775] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1072.448096][T87171] show_signal_msg: 131 callbacks suppressed
[ 1072.448138][T87171] file0[87171]: segfault at 0 ip 0000000000000000 sp 00000000ffa98450 error 14 likely on CPU 0 (core 0, socket 0)
[ 1072.454254][T87171] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1072.484935][T87174] file0[87174]: segfault at 0 ip 0000000000000000 sp 00000000ffeab3f0 error 14 likely on CPU 2 (core 2, socket 0)
[ 1072.488197][T87174] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1072.516383][T87177] file0[87177]: segfault at 0 ip 0000000000000000 sp 00000000ffaae010 error 14 likely on CPU 2 (core 2, socket 0)
[ 1072.519135][T87177] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1072.554809][T87180] file0[87180]: segfault at 0 ip 0000000000000000 sp 00000000ffb5b5d0 error 14 likely on CPU 0 (core 0, socket 0)
[ 1072.558320][T87180] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1072.597047][T87183] file0[87183]: segfault at 0 ip 0000000000000000 sp 00000000ffc0d010 error 14 likely on CPU 3 (core 3, socket 0)
[ 1072.602051][T87183] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1072.634884][T87186] file0[87186]: segfault at 0 ip 0000000000000000 sp 00000000fff14a00 error 14 likely on CPU 3 (core 3, socket 0)
[ 1072.637677][T87186] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1072.670330][T87189] file0[87189]: segfault at 0 ip 0000000000000000 sp 00000000ffdc5ba0 error 14 likely on CPU 2 (core 2, socket 0)
[ 1072.674944][T87189] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1072.707693][T87192] file0[87192]: segfault at 0 ip 0000000000000000 sp 00000000ff81a310 error 14 likely on CPU 3 (core 3, socket 0)
[ 1072.711030][T87192] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1072.746245][T87195] file0[87195]: segfault at 0 ip 0000000000000000 sp 00000000ffcba4c0 error 14 likely on CPU 2 (core 2, socket 0)
[ 1072.749589][T87195] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1072.804519][T87198] file0[87198]: segfault at 0 ip 0000000000000000 sp 00000000ffb3f2e0 error 14 likely on CPU 2 (core 2, socket 0)
[ 1072.808302][T87198] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1077.474275][T87600] show_signal_msg: 133 callbacks suppressed
[ 1077.474300][T87600] file0[87600]: segfault at 0 ip 0000000000000000 sp 00000000ff93ec70 error 14 likely on CPU 3 (core 3, socket 0)
[ 1077.478821][T87600] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1077.524406][T87603] file0[87603]: segfault at 0 ip 0000000000000000 sp 00000000ff953d80 error 14 likely on CPU 0 (core 0, socket 0)
[ 1077.525923][T87603] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1077.555423][T87606] file0[87606]: segfault at 0 ip 0000000000000000 sp 00000000ffe75a70 error 14 likely on CPU 1 (core 1, socket 0)
[ 1077.558507][T87606] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1077.588132][T87609] file0[87609]: segfault at 0 ip 0000000000000000 sp 00000000ffd56540 error 14 likely on CPU 2 (core 2, socket 0)
[ 1077.593234][T87609] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1077.626408][T87612] file0[87612]: segfault at 0 ip 0000000000000000 sp 00000000ffc52fa0 error 14 likely on CPU 1 (core 1, socket 0)
[ 1077.629483][T87612] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1077.683556][T87615] file0[87615]: segfault at 0 ip 0000000000000000 sp 00000000ffc26c70 error 14 likely on CPU 1 (core 1, socket 0)
[ 1077.687222][T87615] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1077.715768][T87618] file0[87618]: segfault at 0 ip 0000000000000000 sp 00000000ffaeb680 error 14 likely on CPU 1 (core 1, socket 0)
[ 1077.718187][T87618] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1077.747347][T87621] file0[87621]: segfault at 0 ip 0000000000000000 sp 00000000ffed1bc0 error 14 likely on CPU 2 (core 2, socket 0)
[ 1077.752279][T87621] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1077.786955][T87624] file0[87624]: segfault at 0 ip 0000000000000000 sp 00000000fffd67a0 error 14 likely on CPU 3 (core 3, socket 0)
[ 1077.790007][T87624] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1077.824414][T87627] file0[87627]: segfault at 0 ip 0000000000000000 sp 00000000ffcf6640 error 14 likely on CPU 2 (core 2, socket 0)
[ 1077.828359][T87627] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1082.490512][T88029] show_signal_msg: 133 callbacks suppressed
[ 1082.490547][T88029] file0[88029]: segfault at 0 ip 0000000000000000 sp 00000000ffd06390 error 14 likely on CPU 3 (core 3, socket 0)
[ 1082.496916][T88029] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1082.534097][T88032] file0[88032]: segfault at 0 ip 0000000000000000 sp 00000000ffb88930 error 14 likely on CPU 2 (core 2, socket 0)
[ 1082.537376][T88032] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1082.566114][T88035] file0[88035]: segfault at 0 ip 0000000000000000 sp 00000000ffa350e0 error 14 likely on CPU 2 (core 2, socket 0)
[ 1082.569127][T88035] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1082.602424][T88038] file0[88038]: segfault at 0 ip 0000000000000000 sp 00000000ffdea7f0 error 14 likely on CPU 1 (core 1, socket 0)
[ 1082.606663][T88038] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1082.640203][T88041] file0[88041]: segfault at 0 ip 0000000000000000 sp 00000000ffdfcae0 error 14 likely on CPU 3 (core 3, socket 0)
[ 1082.645152][T88041] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1082.675764][T88044] file0[88044]: segfault at 0 ip 0000000000000000 sp 00000000ffaee680 error 14 likely on CPU 3 (core 3, socket 0)
[ 1082.678326][T88044] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1082.736312][T88047] file0[88047]: segfault at 0 ip 0000000000000000 sp 00000000ff8fb1f0 error 14 likely on CPU 3 (core 3, socket 0)
[ 1082.741330][T88047] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1082.796604][T88050] file0[88050]: segfault at 0 ip 0000000000000000 sp 00000000ffb7df60 error 14 likely on CPU 2 (core 2, socket 0)
[ 1082.800611][T88050] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1082.831050][T88053] file0[88053]: segfault at 0 ip 0000000000000000 sp 00000000ffea0dd0 error 14 likely on CPU 2 (core 2, socket 0)
[ 1082.835482][T88053] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1082.878046][T88056] file0[88056]: segfault at 0 ip 0000000000000000 sp 00000000ffbc6620 error 14 likely on CPU 2 (core 2, socket 0)
[ 1082.879520][T88056] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1087.503247][T88445] ==================================================================
[ 1087.506593][T88445] BUG: KASAN: slab-use-after-free in kill_orphaned_pgrp+0x2e1/0x340
[ 1087.509999][T88445] Read of size 8 at addr ffff888159498938 by task vhost-88444/88445
[ 1087.512980][T88445]
[ 1087.513587][T88445] CPU: 0 PID: 88445 Comm: vhost-88444 Not tainted 6.6.0-rc1 #3
[ 1087.515430][T88445] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.15.0-0-g2dd4b9b3f840-prebuilt.qemu.org 04/01/2014
[ 1087.518366][T88445] Call Trace:
[ 1087.519200][T88445]  <TASK>

[xingwei lee]

Hi. With my best effort, I have reproduced this bug with repro.c and repro.txt below, Without analyzing deeply, I find the bug may also trigger titled "KASAN: slab-use-after-free read in do_acct_process" because of the same reproducer., And when I test for this bug, it's also report the error like below:, 

[xingwei lee]

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.

And when I test for this bug, it's also report the error like below:

[ 1062.533765][T86339] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[ 1062.562117][T86342] file0[86342]: segfault at 0 ip 0000000000000000 sp 00000000ffb7a1f0 error 14 likely on CPU 0 (core 0, socket 0)

[xingwei lee]

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

[xingwei lee]

[xingwei lee]

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

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 0bb80ecc33a8 Linux 6.6-rc1
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=139b08d8680000
kernel config: https://syzkaller.appspot.com/x/.config?x=f4894cf58531f
dashboard link: https://syzkaller.appspot.com/bug?extid=50ef815ba3bcce06d409
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/eeb0cac260c7/disk-0bb80ecc.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a3c360110254/vmlinux-0bb80ecc.xz
kernel image: https://storage.googleapis.com/syzbot-assets/22b81065ba5f/bzImage-0bb80ecc.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+50ef81...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-use-after-free in task_pgrp include/linux/sched/signal.h:694 [inline]
BUG: KASAN: slab-use-after-free in kill_orphaned_pgrp+0x2e1/0x340 kernel/exit.c:376
Read of size 8 at addr ffff88802d78a6b8 by task vhost-16506/16518

CPU: 0 PID: 16518 Comm: vhost-16506 Not tainted 6.6.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/04/2023
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:364 [inline]
print_report+0xc4/0x620 mm/kasan/report.c:475
kasan_report+0xda/0x110 mm/kasan/report.c:588
task_pgrp include/linux/sched/signal.h:694 [inline]
kill_orphaned_pgrp+0x2e1/0x340 kernel/exit.c:376
exit_notify kernel/exit.c:737 [inline]
do_exit+0x1cb5/0x2a20 kernel/exit.c:894
vhost_task_fn+0x2e6/0x370 kernel/vhost_task.c:61
ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304
</TASK>

Allocated by task 5090:
kasan_save_stack+0x33/0x50 mm/kasan/common.c:45
kasan_set_track+0x25/0x30 mm/kasan/common.c:52
__kasan_slab_alloc+0x81/0x90 mm/kasan/common.c:328
kasan_slab_alloc include/linux/kasan.h:188 [inline]
slab_post_alloc_hook mm/slab.h:762 [inline]
slab_alloc_node mm/slub.c:3478 [inline]
kmem_cache_alloc_node+0x185/0x3f0 mm/slub.c:3523
alloc_task_struct_node kernel/fork.c:173 [inline]
dup_task_struct kernel/fork.c:1110 [inline]
copy_process+0x41c/0x7400 kernel/fork.c:2327
kernel_clone+0xfd/0x930 kernel/fork.c:2909
__do_sys_clone+0xba/0x100 kernel/fork.c:3052
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

Freed by task 42:
kasan_save_stack+0x33/0x50 mm/kasan/common.c:45
kasan_set_track+0x25/0x30 mm/kasan/common.c:52
kasan_save_free_info+0x2b/0x40 mm/kasan/generic.c:522
____kasan_slab_free mm/kasan/common.c:236 [inline]
____kasan_slab_free+0x15b/0x1b0 mm/kasan/common.c:200
kasan_slab_free include/linux/kasan.h:164 [inline]
slab_free_hook mm/slub.c:1800 [inline]
slab_free_freelist_hook+0x114/0x1e0 mm/slub.c:1826
slab_free mm/slub.c:3809 [inline]
kmem_cache_free+0xf0/0x480 mm/slub.c:3831
put_task_struct include/linux/sched/task.h:136 [inline]
put_task_struct include/linux/sched/task.h:123 [inline]
delayed_put_task_struct+0x246/0x2c0 kernel/exit.c:226
rcu_do_batch kernel/rcu/tree.c:2139 [inline]
rcu_core+0x7fb/0x1bb0 kernel/rcu/tree.c:2403
__do_softirq+0x218/0x965 kernel/softirq.c:553

Last potentially related work creation:
kasan_save_stack+0x33/0x50 mm/kasan/common.c:45
__kasan_record_aux_stack+0xbc/0xd0 mm/kasan/generic.c:492
__call_rcu_common.constprop.0+0x9a/0x790 kernel/rcu/tree.c:2653
put_task_struct_rcu_user kernel/exit.c:232 [inline]
put_task_struct_rcu_user+0x87/0xc0 kernel/exit.c:229
release_task+0xf0a/0x1b90 kernel/exit.c:282
de_thread fs/exec.c:1158 [inline]
begin_new_exec+0x226c/0x3110 fs/exec.c:1264
load_elf_binary+0x8ec/0x5c40 fs/binfmt_elf.c:1001
search_binary_handler fs/exec.c:1739 [inline]
exec_binprm fs/exec.c:1781 [inline]
bprm_execve fs/exec.c:1856 [inline]
bprm_execve+0x80a/0x1a50 fs/exec.c:1812
do_execveat_common.isra.0+0x5d3/0x740 fs/exec.c:1964
do_execve fs/exec.c:2038 [inline]
__do_sys_execve fs/exec.c:2114 [inline]
__se_sys_execve fs/exec.c:2109 [inline]
__x64_sys_execve+0x8c/0xb0 fs/exec.c:2109
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

Second to last potentially related work creation:
kasan_save_stack+0x33/0x50 mm/kasan/common.c:45
__kasan_record_aux_stack+0xbc/0xd0 mm/kasan/generic.c:492
__call_rcu_common.constprop.0+0x9a/0x790 kernel/rcu/tree.c:2653
put_task_struct_rcu_user kernel/exit.c:232 [inline]
put_task_struct_rcu_user+0x87/0xc0 kernel/exit.c:229
context_switch kernel/sched/core.c:5385 [inline]
__schedule+0xee9/0x59f0 kernel/sched/core.c:6695
preempt_schedule_irq+0x52/0x90 kernel/sched/core.c:7007
irqentry_exit+0x35/0x80 kernel/entry/common.c:432
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:645

The buggy address belongs to the object at ffff88802d789dc0
which belongs to the cache task_struct of size 7360
The buggy address is located 2296 bytes inside of
freed 7360-byte region [ffff88802d789dc0, ffff88802d78ba80)

The buggy address belongs to the physical page:
page:ffffea0000b5e200 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2d788
head:ffffea0000b5e200 order:3 entire_mapcount:0 nr_pages_mapped:0 pincount:0
memcg:ffff888075f26101
flags: 0xfff00000000840(slab|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000840 ffff888014e49500 ffffea0001e00e00 dead000000000002
raw: 0000000000000000 0000000000040004 00000001ffffffff ffff888075f26101
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 5278, tgid 5278 (syz-executor.3), ts 190312746205, free_ts 190291479937
set_page_owner include/linux/page_owner.h:31 [inline]
post_alloc_hook+0x2cf/0x340 mm/page_alloc.c:1536
prep_new_page mm/page_alloc.c:1543 [inline]
get_page_from_freelist+0xee0/0x2f20 mm/page_alloc.c:3170
__alloc_pages+0x1d0/0x4a0 mm/page_alloc.c:4426
alloc_pages+0x1a9/0x270 mm/mempolicy.c:2298
alloc_slab_page mm/slub.c:1870 [inline]
allocate_slab+0x251/0x380 mm/slub.c:2017
new_slab mm/slub.c:2070 [inline]
___slab_alloc+0x8be/0x1570 mm/slub.c:3223
__slab_alloc.constprop.0+0x56/0xa0 mm/slub.c:3322
__slab_alloc_node mm/slub.c:3375 [inline]
slab_alloc_node mm/slub.c:3468 [inline]
kmem_cache_alloc_node+0x137/0x3f0 mm/slub.c:3523
alloc_task_struct_node kernel/fork.c:173 [inline]
dup_task_struct kernel/fork.c:1110 [inline]
copy_process+0x41c/0x7400 kernel/fork.c:2327
kernel_clone+0xfd/0x930 kernel/fork.c:2909
__do_sys_clone3+0x1f1/0x260 kernel/fork.c:3210
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1136 [inline]
free_unref_page_prepare+0x476/0xa40 mm/page_alloc.c:2312
free_unref_page+0x33/0x3b0 mm/page_alloc.c:2405
__folio_put+0xeb/0x110 mm/swap.c:127
folio_put include/linux/mm.h:1475 [inline]
put_page include/linux/mm.h:1544 [inline]
do_exit+0x2332/0x2a20 kernel/exit.c:913
do_group_exit+0xd4/0x2a0 kernel/exit.c:1024
get_signal+0x23d1/0x27b0 kernel/signal.c:2892
arch_do_signal_or_restart+0x90/0x7f0 arch/x86/kernel/signal.c:309
exit_to_user_mode_loop kernel/entry/common.c:168 [inline]
exit_to_user_mode_prepare+0x11f/0x240 kernel/entry/common.c:204
__syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline]
syscall_exit_to_user_mode+0x1d/0x60 kernel/entry/common.c:296
do_syscall_64+0x44/0xb0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x63/0xcd

Memory state around the buggy address:
ffff88802d78a580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88802d78a600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88802d78a680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88802d78a700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88802d78a780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.