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Date: Mon, 4 Dec 2023 20:32:24 +0800
From: xingwei lee <xrivendell7@...il.com>
To: syzbot+db9ad150a8969744d703@...kaller.appspotmail.com
Cc: andrii@...nel.org, ast@...nel.org, bpf@...r.kernel.org,
daniel@...earbox.net, haoluo@...gle.com, john.fastabend@...il.com,
jolsa@...nel.org, kpsingh@...nel.org, linux-kernel@...r.kernel.org,
linux-trace-kernel@...r.kernel.org, martin.lau@...ux.dev,
mhiramat@...nel.org, rostedt@...dmis.org, sdf@...gle.com,
song@...nel.org, syzkaller-bugs@...glegroups.com,
yonghong.song@...ux.dev
Subject: Re: [syzbot] [bpf?] [trace?] possible deadlock in dev_watchdog
hello
I reproduced this bug with repro.c and repro.txt
=* repro.txt =*
r0 = syz_clone(0x0, 0x0, 0x0, 0x0, 0x0, 0x0)
ptrace(0x10, r0)
r1 = bpf$BPF_PROG_RAW_TRACEPOINT_LOAD(0x5, &(0x7f0000000200)={0x18,
0x4, &(0x7f00000002c0)=ANY=[@ANYBLOB="180100001c00000000000000120000f1850000006d00000095"],
&(0x7f0000000000)='GPL\x00', 0x0, 0x0, 0x0, 0x0, 0x0, '\x00', 0x0,
0x2}, 0x80)
bpf$BPF_RAW_TRACEPOINT_OPEN(0x11,
&(0x7f0000000200)={&(0x7f0000000340)='kfree\x00', r1}, 0x10)
=* repro.c =*
// autogenerated by syzkaller (https://github.com/google/syzkaller)
#include <dirent.h>
#include <endian.h>
#include <errno.h>
#include <fcntl.h>
#include <sched.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>
#ifndef __NR_bpf
#define __NR_bpf 321
#endif
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 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");
}
#define USLEEP_FORKED_CHILD (3 * 50 * 1000)
static long handle_clone_ret(long ret) {
if (ret != 0) {
return ret;
}
usleep(USLEEP_FORKED_CHILD);
syscall(__NR_exit, 0);
while (1) {
}
}
static long syz_clone(volatile long flags, volatile long stack,
volatile long stack_len, volatile long ptid,
volatile long ctid, volatile long tls) {
long sp = (stack + stack_len) & ~15;
long ret = (long)syscall(__NR_clone, flags & ~CLONE_VM, sp, ptid, ctid, tls);
return handle_clone_ret(ret);
}
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] = {0x0, 0xffffffffffffffff};
void execute_one(void) {
intptr_t res = 0;
res = -1;
res = syz_clone(/*flags=*/0, /*stack=*/0, /*stack_len=*/0, /*parentid=*/0,
/*childtid=*/0, /*tls=*/0);
if (res != -1) r[0] = res;
syscall(__NR_ptrace, /*req=*/0x10ul, /*pid=*/r[0], 0, 0);
*(uint32_t*)0x20000200 = 0x18;
*(uint32_t*)0x20000204 = 4;
*(uint64_t*)0x20000208 = 0x200002c0;
memcpy((void*)0x200002c0,
"\x18\x01\x00\x00\x1c\x00\x00\x00\x00\x00\x00\x00\x12\x00\x00\xf1\x85"
"\x00\x00\x00\x6d\x00\x00\x00\x95",
25);
*(uint64_t*)0x20000210 = 0x20000000;
memcpy((void*)0x20000000, "GPL\000", 4);
*(uint32_t*)0x20000218 = 0;
*(uint32_t*)0x2000021c = 0;
*(uint64_t*)0x20000220 = 0;
*(uint32_t*)0x20000228 = 0;
*(uint32_t*)0x2000022c = 0;
memset((void*)0x20000230, 0, 16);
*(uint32_t*)0x20000240 = 0;
*(uint32_t*)0x20000244 = 2;
*(uint32_t*)0x20000248 = -1;
*(uint32_t*)0x2000024c = 8;
*(uint64_t*)0x20000250 = 0;
*(uint32_t*)0x20000258 = 0;
*(uint32_t*)0x2000025c = 0x10;
*(uint64_t*)0x20000260 = 0;
*(uint32_t*)0x20000268 = 0;
*(uint32_t*)0x2000026c = 0;
*(uint32_t*)0x20000270 = 0;
*(uint32_t*)0x20000274 = 0;
*(uint64_t*)0x20000278 = 0;
*(uint64_t*)0x20000280 = 0;
*(uint32_t*)0x20000288 = 0x10;
*(uint32_t*)0x2000028c = 0;
res = syscall(__NR_bpf, /*cmd=*/5ul, /*arg=*/0x20000200ul, /*size=*/0x80ul);
if (res != -1) r[1] = res;
*(uint64_t*)0x20000200 = 0x20000340;
memcpy((void*)0x20000340, "kfree\000", 6);
*(uint32_t*)0x20000208 = r[1];
syscall(__NR_bpf, /*cmd=*/0x11ul, /*arg=*/0x20000200ul, /*size=*/0x10ul);
}
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;
}
and also https://gist.github.com/xrivendell7/569542ed0113dc5f98753ea8c5305912
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