Hello I found a bug titled "BUG: unable to handle kernel paging request in fuse_copy_do” with modified syzkaller, and maybe it is related to fs/fuse. I also confirmed in the latest upstream. If you fix this issue, please add the following tag to the commit: Reported-by: xingwei lee <xrivendell7@xxxxxxxxx> Reported-by: yue sun <samsun1006219@xxxxxxxxx> kernel: upstream 23956900041d968f9ad0f30db6dede4daccd7aa9 kernel config: https://syzkaller.appspot.com/text?tag=KernelConfig&x=9f47e8dfa53b0b11 with KASAN enabled compiler: gcc (Debian 12.2.0-14) 12.2.0 BUG: unable to handle kernel paging request in fuse_copy_do UDPLite: UDP-Lite is deprecated and scheduled to be removed in 2025, please contact the netdev mailing list BUG: unable to handle page fault for address: ffff88802c29c000 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 13001067 P4D 13001067 PUD 13002067 PMD 24c8d063 PTE 800fffffd3d63060 Oops: 0000 [#1] PREEMPT SMP KASAN NOPTI CPU: 1 PID: 8221 Comm: 1e9 Not tainted 6.8.0-05202-g9187210eee7d-dirty #21 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-1.fc38 04/01/2014 RIP: 0010:memcpy+0xc/0x20 arch/x86/lib/memcpy_64.S:38 Code: 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 48 89 f80 RSP: 0018:ffffc9001065f9c8 EFLAGS: 00010246 RAX: ffffc9001065fb10 RBX: ffffc9001065fc78 RCX: 0000000000000010 RDX: 0000000000000010 RSI: ffff88802c29c000 RDI: ffffc9001065fb10 RBP: 0000000000000010 R08: ffff88802c29c000 R09: 0000000000000001 R10: ffffffff8ea82ed7 R11: ffffc9001065fd98 R12: ffffc9001065fac0 R13: 0000000000000010 R14: ffffc9001065faf0 R15: ffffc9001065fcbc FS: 000000000f82d480(0000) GS:ffff88823bc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffff88802c29c000 CR3: 000000002dd7c000 CR4: 0000000000750ef0 PKRU: 55555554 Call Trace: <TASK> fuse_copy_do+0x152/0x340 fs/fuse/dev.c:758 fuse_copy_one fs/fuse/dev.c:1007 [inline] fuse_dev_do_write+0x1df/0x26a0 fs/fuse/dev.c:1863 fuse_dev_write+0x129/0x1b0 fs/fuse/dev.c:1960 call_write_iter include/linux/fs.h:2108 [inline] new_sync_write fs/read_write.c:497 [inline] vfs_write+0x62e/0x10a0 fs/read_write.c:590 ksys_write+0xf6/0x1d0 fs/read_write.c:643 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0x7c/0x1d0 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x6c/0x74 =* repro.c =* #define _GNU_SOURCE #include <dirent.h> #include <endian.h> #include <errno.h> #include <fcntl.h> #include <setjmp.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_memfd_secret #define __NR_memfd_secret 447 #endif static __thread int clone_ongoing; static __thread int skip_segv; static __thread jmp_buf segv_env; static void segv_handler(int sig, siginfo_t* info, void* ctx) { if (__atomic_load_n(&clone_ongoing, __ATOMIC_RELAXED) != 0) { exit(sig); } uintptr_t addr = (uintptr_t)info->si_addr; const uintptr_t prog_start = 1 << 20; const uintptr_t prog_end = 100 << 20; int skip = __atomic_load_n(&skip_segv, __ATOMIC_RELAXED) != 0; int valid = addr < prog_start || addr > prog_end; if (skip && valid) { _longjmp(segv_env, 1); } exit(sig); } static void install_segv_handler(void) { struct sigaction sa; memset(&sa, 0, sizeof(sa)); sa.sa_handler = SIG_IGN; syscall(SYS_rt_sigaction, 0x20, &sa, NULL, 8); syscall(SYS_rt_sigaction, 0x21, &sa, NULL, 8); memset(&sa, 0, sizeof(sa)); sa.sa_sigaction = segv_handler; sa.sa_flags = SA_NODEFER | SA_SIGINFO; sigaction(SIGSEGV, &sa, NULL); sigaction(SIGBUS, &sa, NULL); } #define NONFAILING(...) \ ({ \ int ok = 1; \ __atomic_fetch_add(&skip_segv, 1, __ATOMIC_SEQ_CST); \ if (_setjmp(segv_env) == 0) { \ __VA_ARGS__; \ } else \ ok = 0; \ __atomic_fetch_sub(&skip_segv, 1, __ATOMIC_SEQ_CST); \ ok; \ }) 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[3] = {0xffffffffffffffff, 0xffffffffffffffff, 0xffffffffffffffff}; void execute_one(void) { intptr_t res = 0; NONFAILING(memcpy((void*)0x20002040, "./file0\000", 8)); syscall(__NR_mkdirat, /*fd=*/0xffffff9c, /*path=*/0x20002040ul, /*mode=*/0ul); NONFAILING(memcpy((void*)0x20002080, "/dev/fuse\000", 10)); res = syscall(__NR_openat, /*fd=*/0xffffffffffffff9cul, /*file=*/0x20002080ul, /*flags=*/2ul, /*mode=*/0ul); if (res != -1) r[0] = res; NONFAILING(memcpy((void*)0x200020c0, "./file0\000", 8)); NONFAILING(memcpy((void*)0x20002100, "fuse\000", 5)); NONFAILING(memcpy((void*)0x20002140, "fd", 2)); NONFAILING(*(uint8_t*)0x20002142 = 0x3d); NONFAILING(sprintf((char*)0x20002143, "0x%016llx", (long long)r[0])); NONFAILING(*(uint8_t*)0x20002155 = 0x2c); NONFAILING(memcpy((void*)0x20002156, "rootmode", 8)); NONFAILING(*(uint8_t*)0x2000215e = 0x3d); NONFAILING(sprintf((char*)0x2000215f, "%023llo", (long long)0x4000)); NONFAILING(*(uint8_t*)0x20002176 = 0x2c); NONFAILING(memcpy((void*)0x20002177, "user_id", 7)); NONFAILING(*(uint8_t*)0x2000217e = 0x3d); NONFAILING(sprintf((char*)0x2000217f, "%020llu", (long long)0)); NONFAILING(*(uint8_t*)0x20002193 = 0x2c); NONFAILING(memcpy((void*)0x20002194, "group_id", 8)); NONFAILING(*(uint8_t*)0x2000219c = 0x3d); NONFAILING(sprintf((char*)0x2000219d, "%020llu", (long long)0)); NONFAILING(*(uint8_t*)0x200021b1 = 0x2c); NONFAILING(*(uint8_t*)0x200021b2 = 0); syscall(__NR_mount, /*src=*/0ul, /*dst=*/0x200020c0ul, /*type=*/0x20002100ul, /*flags=*/0ul, /*opts=*/0x20002140ul); res = syscall(__NR_memfd_secret, /*flags=*/0ul); if (res != -1) r[1] = res; syscall(__NR_mmap, /*addr=*/0x20000000ul, /*len=*/0xb36000ul, /*prot=PROT_GROWSUP|PROT_READ*/ 0x2000001ul, /*flags=MAP_STACK|MAP_POPULATE|MAP_FIXED|MAP_SHARED*/ 0x28011ul, /*fd=*/r[1], /*offset=*/0ul); syscall(__NR_ftruncate, /*fd=*/r[1], /*len=*/7ul); res = syscall(__NR_socket, /*domain=*/2ul, /*type=*/2ul, /*proto=*/0x88); if (res != -1) r[2] = res; NONFAILING(*(uint32_t*)0x20000280 = 0); syscall(__NR_getsockopt, /*fd=*/r[2], /*level=*/1, /*optname=*/0x11, /*optval=*/0ul, /*optlen=*/0x20000280ul); NONFAILING(*(uint32_t*)0x20000000 = 0x50); NONFAILING(*(uint32_t*)0x20000004 = 0); NONFAILING(*(uint64_t*)0x20000008 = 0); NONFAILING(*(uint32_t*)0x20000010 = 7); NONFAILING(*(uint32_t*)0x20000014 = 0x27); NONFAILING(*(uint32_t*)0x20000018 = 0); NONFAILING(*(uint32_t*)0x2000001c = 0); NONFAILING(*(uint16_t*)0x20000020 = 0); NONFAILING(*(uint16_t*)0x20000022 = 0); NONFAILING(*(uint32_t*)0x20000024 = 0); NONFAILING(*(uint32_t*)0x20000028 = 0); NONFAILING(*(uint16_t*)0x2000002c = 0); NONFAILING(*(uint16_t*)0x2000002e = 0); NONFAILING(memset((void*)0x20000030, 0, 32)); syscall(__NR_write, /*fd=*/r[0], /*arg=*/0x20000000ul, /*len=*/0x50ul); } 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); install_segv_handler(); loop(); return 0; } =* repro.txt =* mkdirat(0xffffffffffffff9c, &(0x7f0000002040)='./file0\x00', 0x0) r0 = openat$fuse(0xffffffffffffff9c, &(0x7f0000002080), 0x2, 0x0) mount$fuse(0x0, &(0x7f00000020c0)='./file0\x00', &(0x7f0000002100), 0x0, &(0x7f0000002140)={{'fd', 0x3d, r0}, 0x2c, {'rootmode', 0x3d, 0x4000}}) r1 = memfd_secret(0x0) mmap(&(0x7f0000000000/0xb36000)=nil, 0xb36000, 0x2000001, 0x28011, r1, 0x0) ftruncate(r1, 0x7) r2 = socket$inet_udplite(0x2, 0x2, 0x88) getsockopt$sock_cred(r2, 0x1, 0x11, 0x0, &(0x7f0000000280)) write$FUSE_INIT(r0, &(0x7f0000000000)={0x50}, 0x50) see aslo https://gist.github.com/xrivendell7/961be96ae091c9671bb56efea902cec4. I hope it helps. best regards. xingwei Lee
