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Message-ID: <CAKfTPtBWtrcpagubeB4BS8p0NQd9fSsJJny8YWb2QHgTmZ4Wnw@mail.gmail.com>
Date: Fri, 30 Aug 2024 14:45:15 +0200
From: Vincent Guittot <vincent.guittot@...aro.org>
To: Xingyu Li <xli399@....edu>
Cc: mingo@...hat.com, peterz@...radead.org, juri.lelli@...hat.com,
dietmar.eggemann@....com, rostedt@...dmis.org, bsegall@...gle.com,
mgorman@...e.de, vschneid@...hat.com, linux-kernel@...r.kernel.org,
Yu Hao <yhao016@....edu>
Subject: Re: BUG: WARNING: ODEBUG bug in schedule_timeout
On Fri, 30 Aug 2024 at 14:43, Vincent Guittot
<vincent.guittot@...aro.org> wrote:
>
> Hi Xingyu,
>
> On Wed, 28 Aug 2024 at 23:05, Xingyu Li <xli399@....edu> wrote:
> >
> > Hi,
> >
> > We found a bug in Linux 6.10. It is possibly a use-before-initialization bug.
...
> >
> > C reproducer:
> > // autogenerated by syzkaller (https://github.com/google/syzkaller)
I tried the reproducer below on my system but nothing happens after a
night of run
> >
> > #define _GNU_SOURCE
> >
> > #include <dirent.h>
> > #include <endian.h>
> > #include <errno.h>
> > #include <fcntl.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>
> >
> > 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 long syz_open_dev(volatile long a0, volatile long a1, volatile 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;
> > 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 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");
> > }
> >
> > 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 (;;) {
> > sleep_ms(10);
> > if (waitpid(-1, &status, WNOHANG | WAIT_FLAGS) == pid)
> > break;
> > if (current_time_ms() - start < 5000)
> > continue;
> > kill_and_wait(pid, &status);
> > break;
> > }
> > }
> > }
> >
> > uint64_t r[1] = {0xffffffffffffffff};
> >
> > void execute_one(void)
> > {
> > intptr_t res = 0;
> > if (write(1, "executing program\n", sizeof("executing program\n") - 1)) {
> > }
> > memcpy((void*)0x20000000,
> > "\x2b\x95\x24\x80\xc7\xca\x55\x09\x7d\x17\x07\x93\x5b\xa6\x4b\x20\xf3"
> > "\x02\x6c\x03\xd6\x58\x02\x6b\x81\xbf\x26\x43\x40\x51\x2b\x3c\xb4\xe0"
> > "\x1a\xfd\xa2\xde\x75\x42\x99\xea\x7a\x11\x33\x43\xab\x7b\x9b\xda\x2f"
> > "\xc0\xa2\xe2\xcd\xbf\xec\xbc\xa0\x23\x3a\x07\x72\xb1\x2e\xbd\xe5\xd9"
> > "\x8a\x12\x03\xcb\x87\x16\x72\xdf\xf7\xe4\xc8\x6e\xc1\xdc\xce\xf0\xa7"
> > "\x63\x12\xfb\xe8\xd4\x5d\xc2\xbd\x0f\x8f\xc2\xeb\xeb\x2a\x6b\xe6\xa3"
> > "\x00\x91\x6c\x52\x81\xda\x2c\x1e\xf6\x4d\x66\x26\x70\x91\xb8\x24\x29"
> > "\x97\x6c\x01\x9d\xa3\x64\x55\x57\xed\x1d\x43\x9c\x5a\x63\x7f\x6b\xf5"
> > "\x8c\x53\xbc\x41\x45\x39\xdd\x87\xc6\x90\x98\xd6\x71\x40\x25\x86\xb6"
> > "\x31\xf9\xac\x5c\x2f\xe9\xce\xdc\x28\x1a\x6f\x00\x5b\x5c\x4d\x1d\xd5"
> > "\xed\x9b\xe4\x00\x00\x00\x00\x00\x00\x00",
> > 180);
> > syscall(__NR_write, /*fd=*/-1, /*arg0=*/0x20000000ul, /*len=*/0xb4ul);
> > memcpy((void*)0x20000080, "/dev/sg#\000", 9);
> > res = -1;
> > res = syz_open_dev(/*dev=*/0x20000080, /*id=*/0,
> > /*flags=O_CREAT|FASYNC|O_RDWR*/ 0x2042);
> > if (res != -1)
> > r[0] = res;
> > *(uint32_t*)0x20000080 = 0;
> > *(uint32_t*)0x20000084 = 2;
> > *(uint8_t*)0x20000088 = 0x85;
> > *(uint8_t*)0x20000089 = 8;
> > *(uint8_t*)0x2000008a = 2;
> > *(uint8_t*)0x2000008b = 0xd;
> > syscall(__NR_ioctl, /*fd=*/r[0], /*arg0=*/1, /*arg1=*/0x20000080ul);
> > }
> > int main(void)
> > {
> > syscall(__NR_mmap, /*addr=*/0x1ffff000ul, /*len=*/0x1000ul, /*prot=*/0ul,
> > /*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/ 0x32ul, /*fd=*/-1,
> > /*offset=*/0ul);
> > syscall(__NR_mmap, /*addr=*/0x20000000ul, /*len=*/0x1000000ul,
> > /*prot=PROT_WRITE|PROT_READ|PROT_EXEC*/ 7ul,
> > /*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/ 0x32ul, /*fd=*/-1,
> > /*offset=*/0ul);
> > syscall(__NR_mmap, /*addr=*/0x21000000ul, /*len=*/0x1000ul, /*prot=*/0ul,
> > /*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/ 0x32ul, /*fd=*/-1,
> > /*offset=*/0ul);
> > const char* reason;
> > (void)reason;
> > loop();
> > return 0;
> > }
> >
> > --
> > Yours sincerely,
> > Xingyu
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