Hello I saw you can't reproduce this bug and I reproduce it with repro.c and repro.txt I test the repro.c in the lastest HEAD: 5e3f5b81de80c98338bcb47c233aebefee5a4801 kernel config: https://syzkaller.appspot.com/text?tag=KernelConfig&x=6ae1a4ee971a7305 and the bug also existed. =* 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 <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 unsigned long long procid; 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"); } 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[5] = {0xffffffffffffffff, 0xffffffffffffffff, 0xffffffffffffffff, 0xffffffffffffffff, 0xffffffffffffffff}; void execute_one(void) { intptr_t res = 0; memcpy((void*)0x20000280, "cgroup.controllers\000", 19); res = syscall(__NR_openat, /*fd=*/0xffffff9c, /*file=*/0x20000280ul, /*flags=*/0x275aul, /*mode=*/0ul); if (res != -1) r[0] = res; memcpy((void*)0x20000180, "cgroup.controllers\000", 19); res = syscall(__NR_openat, /*fd=*/0xffffff9c, /*file=*/0x20000180ul, /*flags=*/0x275aul, /*mode=*/0ul); if (res != -1) r[1] = res; res = syscall(__NR_dup3, /*oldfd=*/r[1], /*newfd=*/r[0], /*flags=*/0ul); if (res != -1) r[2] = res; *(uint32_t*)0x20000140 = 0x20; *(uint32_t*)0x20000144 = 0x8c8c; *(uint32_t*)0x20000148 = 0; *(uint32_t*)0x2000014c = 0; *(uint32_t*)0x20000150 = 0; memset((void*)0x20000154, 0, 8); syscall(__NR_ioctl, /*fd=*/r[0], /*cmd=*/0x401c5820, /*arg=*/0x20000140ul); sprintf((char*)0x20000040, "0x%016llx", (long long)0); syscall(__NR_write, /*fd=*/r[0], /*buf=*/0x20000040ul, /*len=*/0xfea0ul); memcpy((void*)0x200001c0, "cpuset.effective_cpus\000", 22); res = syscall(__NR_openat, /*fd=*/0xffffff9c, /*file=*/0x200001c0ul, /*flags=*/0x275aul, /*mode=*/0ul); if (res != -1) r[3] = res; sprintf((char*)0x20000380, "0x%016llx", (long long)0); syscall(__NR_write, /*fd=*/r[3], /*buf=*/0x20000380ul, /*len=*/0x101bful); syscall(__NR_ioctl, /*fd=*/r[3], /*cmd=*/0x660c, 0); *(uint32_t*)0x200000c0 = 0; *(uint32_t*)0x200000c4 = r[3]; *(uint64_t*)0x200000c8 = 7; *(uint64_t*)0x200000d0 = 0; *(uint64_t*)0x200000d8 = 0; *(uint64_t*)0x200000e0 = 0; syscall(__NR_ioctl, /*fd=*/r[2], /*cmd=*/0xc028660f, /*arg=*/0x200000c0ul); syscall(__NR_writev, /*fd=*/-1, /*vec=*/0ul, /*vlen=*/0ul); syscall(__NR_ioctl, /*fd=*/-1, /*cmd=*/0x40045569, /*arg=*/9ul); syscall(__NR_openat, /*fd=*/0xffffff9c, /*file=*/0ul, /*flags=*/0x275aul, /*mode=*/0ul); memcpy((void*)0x20000180, "cgroup.controllers\000", 19); res = syscall(__NR_openat, /*fd=*/0xffffff9c, /*file=*/0x20000180ul, /*flags=*/0x275aul, /*mode=*/0ul); if (res != -1) r[4] = res; *(uint64_t*)0x200000c0 = 4; *(uint64_t*)0x200000c8 = 0x16000000000000; *(uint64_t*)0x200000d0 = 0x20; syscall(__NR_ioctl, /*fd=*/r[4], /*cmd=*/0xc0185879, /*arg=*/0x200000c0ul); } 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); for (procid = 0; procid < 4; procid++) { if (fork() == 0) { loop(); } } sleep(1000000); return 0; } =* repro.txt =* r0 = openat$cgroup_ro(0xffffffffffffff9c, &(0x7f0000000280)='cgroup.controllers\x00', 0x275a, 0x0) r1 = openat$cgroup_ro(0xffffffffffffff9c, &(0x7f0000000180)='cgroup.controllers\x00', 0x275a, 0x0) r2 = dup3(r1, r0, 0x0) ioctl$FS_IOC_FSSETXATTR(r0, 0x401c5820, &(0x7f0000000140)={0x20, 0x8c8c}) write$cgroup_int(r0, &(0x7f0000000040), 0xfea0) r3 = openat$cgroup_ro(0xffffffffffffff9c, &(0x7f00000001c0)='cpuset.effective_cpus\x00', 0x275a, 0x0) write$cgroup_int(r3, &(0x7f0000000380), 0x101bf) ioctl$EXT4_IOC_ALLOC_DA_BLKS(r3, 0x660c) ioctl$EXT4_IOC_MOVE_EXT(r2, 0xc028660f, &(0x7f00000000c0)={0x0, r3, 0x7}) writev(0xffffffffffffffff, 0x0, 0x0) ioctl$UI_SET_LEDBIT(0xffffffffffffffff, 0x40045569, 0x9) openat$cgroup_ro(0xffffffffffffff9c, 0x0, 0x275a, 0x0) r4 = openat$cgroup_ro(0xffffffffffffff9c, &(0x7f0000000180)='cgroup.controllers\x00', 0x275a, 0x0) ioctl$FITRIM(r4, 0xc0185879, &(0x7f00000000c0)={0x4, 0x16000000000000, 0x20}) and also https://gist.github.com/xrivendell7/bad992c2b716ed14310efa2c6f878b7c
