Hello I found a bug in latest upstream titled "WARNING in ovl_copy_up_file" with modified syzkaller and maybe is related with overlays, and I also reproduce it with repro.c and repro.txt If you fix this issue, please add the following tag to the commit: Reported-by: xingwei lee <xrivendell7@xxxxxxxxx> kernel: upstream 021533194476035883300d60fbb3136426ac8ea5 kernel config: https://syzkaller.appspot.com/text?tag=KernelConfig&x=457249c250b93697 with KASAN enabled compiler: gcc (Debian 12.2.0-14) 12.2.0 ------------[ cut here ]------------ WARNING: CPU: 3 PID: 77145 at fs/overlayfs/copy_up.c:239 ovl_copy_up_file+0x6ca/0x6f0 fs/overlayfs/copy_up.c:332 Modules linked in: CPU: 3 PID: 77145 Comm: syz-executor.0 Not tainted 6.8.0-rc1-00208-g6af191034c8f-dirty #3 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 RIP: 0010:ovl_verify_area fs/overlayfs/copy_up.c:239 [inline] RIP: 0010:ovl_copy_up_file+0x6ca/0x6f0 fs/overlayfs/copy_up.c:332 Code: ff e8 6a 62 47 ff 0f 0b 41 bc fb ff ff ff 48 8b 5c 24 18 e9 7c ff ff ff 31 ff e8 51 62 47 ff 0f 0b eb 14 31 ff e8 46 62 47 ff <0f> 0b eb 09 31 ff e8 3b 62 47 ff 0f 0b 41 bc fb ff ff ff e9 1d fb RSP: 0018:ffff88804417f440 EFLAGS: 00010246 RAX: ffffffff81fb8c4a RBX: 0000000000800000 RCX: ffffc9000c04c000 RDX: ffffffff81fb8c4a RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffff88804417f570 R08: 000000000000a4dd R09: 000000000000a4de R10: ffffed102063f949 R11: ffffed102063f949 R12: ffff8881031fca40 R13: 0000000000800000 R14: ffff88804417f4c0 R15: ffffffffffeac000 FS: 00007fd4f579c6c0(0000) GS:ffff888135d00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fc0bff9d988 CR3: 0000000013cc4000 CR4: 0000000000752ef0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 PKRU: 55555554 Call Trace: <TASK> ovl_copy_up_tmpfile fs/overlayfs/copy_up.c:865 [inline] ovl_do_copy_up fs/overlayfs/copy_up.c:978 [inline] ovl_copy_up_one fs/overlayfs/copy_up.c:1170 [inline] ovl_copy_up_flags+0x1717/0x2cc0 fs/overlayfs/copy_up.c:1225 ovl_copy_up+0x20/0x30 fs/overlayfs/copy_up.c:1265 ovl_setattr+0xc1/0x370 fs/overlayfs/inode.c:41 notify_change+0x8d2/0x960 fs/attr.c:499 chmod_common+0x1d5/0x330 fs/open.c:648 do_fchmodat fs/open.c:696 [inline] __do_sys_fchmodat fs/open.c:715 [inline] __se_sys_fchmodat fs/open.c:712 [inline] __x64_sys_fchmodat+0xea/0x180 fs/open.c:712 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0x59/0x120 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x63/0x6b RIP: 0033:0x7fd4f647cc29 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fd4f579c0c8 EFLAGS: 00000246 ORIG_RAX: 000000000000010c RAX: ffffffffffffffda RBX: 00007fd4f659c1f0 RCX: 00007fd4f647cc29 RDX: 0000000000000000 RSI: 00000000200000c0 RDI: 0000000000000005 RBP: 00007fd4f64c847a R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 000000000000006e R14: 00007fd4f659c1f0 R15: 00007ffc819fff88 </TASK> ---[ end trace 0000000000000000 ]--- =* 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 <setjmp.h> #include <signal.h> #include <stdarg.h> #include <stdbool.h> #include <stddef.h> #include <stdint.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/ioctl.h> #include <sys/mman.h> #include <sys/mount.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> #include <linux/loop.h> #ifndef __NR_memfd_create #define __NR_memfd_create 319 #endif static unsigned long long procid; 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 void use_temporary_dir(void) { char tmpdir_template[] = "./syzkaller.XXXXXX"; char* tmpdir = mkdtemp(tmpdir_template); if (!tmpdir) exit(1); if (chmod(tmpdir, 0777)) exit(1); if (chdir(tmpdir)) exit(1); } 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; } //% This code is derived from puff.{c,h}, found in the zlib development. The //% original files come with the following copyright notice: //% Copyright (C) 2002-2013 Mark Adler, all rights reserved //% version 2.3, 21 Jan 2013 //% This software is provided 'as-is', without any express or implied //% warranty. In no event will the author be held liable for any damages //% arising from the use of this software. //% Permission is granted to anyone to use this software for any purpose, //% including commercial applications, and to alter it and redistribute it //% freely, subject to the following restrictions: //% 1. The origin of this software must not be misrepresented; you must not //% claim that you wrote the original software. If you use this software //% in a product, an acknowledgment in the product documentation would be //% appreciated but is not required. //% 2. Altered source versions must be plainly marked as such, and must not be //% misrepresented as being the original software. //% 3. This notice may not be removed or altered from any source distribution. //% Mark Adler madler@xxxxxxxxxxxxxxxxxx //% BEGIN CODE DERIVED FROM puff.{c,h} #define MAXBITS 15 #define MAXLCODES 286 #define MAXDCODES 30 #define MAXCODES (MAXLCODES + MAXDCODES) #define FIXLCODES 288 struct puff_state { unsigned char* out; unsigned long outlen; unsigned long outcnt; const unsigned char* in; unsigned long inlen; unsigned long incnt; int bitbuf; int bitcnt; jmp_buf env; }; static int puff_bits(struct puff_state* s, int need) { long val = s->bitbuf; while (s->bitcnt < need) { if (s->incnt == s->inlen) longjmp(s->env, 1); val |= (long)(s->in[s->incnt++]) << s->bitcnt; s->bitcnt += 8; } s->bitbuf = (int)(val >> need); s->bitcnt -= need; return (int)(val & ((1L << need) - 1)); } static int puff_stored(struct puff_state* s) { s->bitbuf = 0; s->bitcnt = 0; if (s->incnt + 4 > s->inlen) return 2; unsigned len = s->in[s->incnt++]; len |= s->in[s->incnt++] << 8; if (s->in[s->incnt++] != (~len & 0xff) || s->in[s->incnt++] != ((~len >> 8) & 0xff)) return -2; if (s->incnt + len > s->inlen) return 2; if (s->outcnt + len > s->outlen) return 1; for (; len--; s->outcnt++, s->incnt++) { if (s->in[s->incnt]) s->out[s->outcnt] = s->in[s->incnt]; } return 0; } struct puff_huffman { short* count; short* symbol; }; static int puff_decode(struct puff_state* s, const struct puff_huffman* h) { int first = 0; int index = 0; int bitbuf = s->bitbuf; int left = s->bitcnt; int code = first = index = 0; int len = 1; short* next = h->count + 1; while (1) { while (left--) { code |= bitbuf & 1; bitbuf >>= 1; int count = *next++; if (code - count < first) { s->bitbuf = bitbuf; s->bitcnt = (s->bitcnt - len) & 7; return h->symbol[index + (code - first)]; } index += count; first += count; first <<= 1; code <<= 1; len++; } left = (MAXBITS + 1) - len; if (left == 0) break; if (s->incnt == s->inlen) longjmp(s->env, 1); bitbuf = s->in[s->incnt++]; if (left > 8) left = 8; } return -10; } static int puff_construct(struct puff_huffman* h, const short* length, int n) { int len; for (len = 0; len <= MAXBITS; len++) h->count[len] = 0; int symbol; for (symbol = 0; symbol < n; symbol++) (h->count[length[symbol]])++; if (h->count[0] == n) return 0; int left = 1; for (len = 1; len <= MAXBITS; len++) { left <<= 1; left -= h->count[len]; if (left < 0) return left; } short offs[MAXBITS + 1]; offs[1] = 0; for (len = 1; len < MAXBITS; len++) offs[len + 1] = offs[len] + h->count[len]; for (symbol = 0; symbol < n; symbol++) if (length[symbol] != 0) h->symbol[offs[length[symbol]]++] = symbol; return left; } static int puff_codes(struct puff_state* s, const struct puff_huffman* lencode, const struct puff_huffman* distcode) { static const short lens[29] = {3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31, 35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258}; static const short lext[29] = {0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 0}; static const short dists[30] = { 1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193, 257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145, 8193, 12289, 16385, 24577}; static const short dext[30] = {0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9, 10, 10, 11, 11, 12, 12, 13, 13}; int symbol; do { symbol = puff_decode(s, lencode); if (symbol < 0) return symbol; if (symbol < 256) { if (s->outcnt == s->outlen) return 1; if (symbol) s->out[s->outcnt] = symbol; s->outcnt++; } else if (symbol > 256) { symbol -= 257; if (symbol >= 29) return -10; int len = lens[symbol] + puff_bits(s, lext[symbol]); symbol = puff_decode(s, distcode); if (symbol < 0) return symbol; unsigned dist = dists[symbol] + puff_bits(s, dext[symbol]); if (dist > s->outcnt) return -11; if (s->outcnt + len > s->outlen) return 1; while (len--) { if (dist <= s->outcnt && s->out[s->outcnt - dist]) s->out[s->outcnt] = s->out[s->outcnt - dist]; s->outcnt++; } } } while (symbol != 256); return 0; } static int puff_fixed(struct puff_state* s) { static int virgin = 1; static short lencnt[MAXBITS + 1], lensym[FIXLCODES]; static short distcnt[MAXBITS + 1], distsym[MAXDCODES]; static struct puff_huffman lencode, distcode; if (virgin) { lencode.count = lencnt; lencode.symbol = lensym; distcode.count = distcnt; distcode.symbol = distsym; short lengths[FIXLCODES]; int symbol; for (symbol = 0; symbol < 144; symbol++) lengths[symbol] = 8; for (; symbol < 256; symbol++) lengths[symbol] = 9; for (; symbol < 280; symbol++) lengths[symbol] = 7; for (; symbol < FIXLCODES; symbol++) lengths[symbol] = 8; puff_construct(&lencode, lengths, FIXLCODES); for (symbol = 0; symbol < MAXDCODES; symbol++) lengths[symbol] = 5; puff_construct(&distcode, lengths, MAXDCODES); virgin = 0; } return puff_codes(s, &lencode, &distcode); } static int puff_dynamic(struct puff_state* s) { static const short order[19] = {16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15}; int nlen = puff_bits(s, 5) + 257; int ndist = puff_bits(s, 5) + 1; int ncode = puff_bits(s, 4) + 4; if (nlen > MAXLCODES || ndist > MAXDCODES) return -3; short lengths[MAXCODES]; int index; for (index = 0; index < ncode; index++) lengths[order[index]] = puff_bits(s, 3); for (; index < 19; index++) lengths[order[index]] = 0; short lencnt[MAXBITS + 1], lensym[MAXLCODES]; struct puff_huffman lencode = {lencnt, lensym}; int err = puff_construct(&lencode, lengths, 19); if (err != 0) return -4; index = 0; while (index < nlen + ndist) { int symbol; int len; symbol = puff_decode(s, &lencode); if (symbol < 0) return symbol; if (symbol < 16) lengths[index++] = symbol; else { len = 0; if (symbol == 16) { if (index == 0) return -5; len = lengths[index - 1]; symbol = 3 + puff_bits(s, 2); } else if (symbol == 17) symbol = 3 + puff_bits(s, 3); else symbol = 11 + puff_bits(s, 7); if (index + symbol > nlen + ndist) return -6; while (symbol--) lengths[index++] = len; } } if (lengths[256] == 0) return -9; err = puff_construct(&lencode, lengths, nlen); if (err && (err < 0 || nlen != lencode.count[0] + lencode.count[1])) return -7; short distcnt[MAXBITS + 1], distsym[MAXDCODES]; struct puff_huffman distcode = {distcnt, distsym}; err = puff_construct(&distcode, lengths + nlen, ndist); if (err && (err < 0 || ndist != distcode.count[0] + distcode.count[1])) return -8; return puff_codes(s, &lencode, &distcode); } static int puff(unsigned char* dest, unsigned long* destlen, const unsigned char* source, unsigned long sourcelen) { struct puff_state s = { .out = dest, .outlen = *destlen, .outcnt = 0, .in = source, .inlen = sourcelen, .incnt = 0, .bitbuf = 0, .bitcnt = 0, }; int err; if (setjmp(s.env) != 0) err = 2; else { int last; do { last = puff_bits(&s, 1); int type = puff_bits(&s, 2); err = type == 0 ? puff_stored(&s) : (type == 1 ? puff_fixed(&s) : (type == 2 ? puff_dynamic(&s) : -1)); if (err != 0) break; } while (!last); } *destlen = s.outcnt; return err; } //% END CODE DERIVED FROM puff.{c,h} #define ZLIB_HEADER_WIDTH 2 static int puff_zlib_to_file(const unsigned char* source, unsigned long sourcelen, int dest_fd) { if (sourcelen < ZLIB_HEADER_WIDTH) return 0; source += ZLIB_HEADER_WIDTH; sourcelen -= ZLIB_HEADER_WIDTH; const unsigned long max_destlen = 132 << 20; void* ret = mmap(0, max_destlen, PROT_WRITE | PROT_READ, MAP_PRIVATE | MAP_ANON, -1, 0); if (ret == MAP_FAILED) return -1; unsigned char* dest = (unsigned char*)ret; unsigned long destlen = max_destlen; int err = puff(dest, &destlen, source, sourcelen); if (err) { munmap(dest, max_destlen); errno = -err; return -1; } if (write(dest_fd, dest, destlen) != (ssize_t)destlen) { munmap(dest, max_destlen); return -1; } return munmap(dest, max_destlen); } static int setup_loop_device(unsigned char* data, unsigned long size, const char* loopname, int* loopfd_p) { int err = 0, loopfd = -1; int memfd = syscall(__NR_memfd_create, "syzkaller", 0); if (memfd == -1) { err = errno; goto error; } if (puff_zlib_to_file(data, size, memfd)) { err = errno; goto error_close_memfd; } loopfd = open(loopname, O_RDWR); if (loopfd == -1) { err = errno; goto error_close_memfd; } if (ioctl(loopfd, LOOP_SET_FD, memfd)) { if (errno != EBUSY) { err = errno; goto error_close_loop; } ioctl(loopfd, LOOP_CLR_FD, 0); usleep(1000); if (ioctl(loopfd, LOOP_SET_FD, memfd)) { err = errno; goto error_close_loop; } } close(memfd); *loopfd_p = loopfd; return 0; error_close_loop: close(loopfd); error_close_memfd: close(memfd); error: errno = err; return -1; } static long syz_mount_image(volatile long fsarg, volatile long dir, volatile long flags, volatile long optsarg, volatile long change_dir, volatile unsigned long size, volatile long image) { unsigned char* data = (unsigned char*)image; int res = -1, err = 0, loopfd = -1, need_loop_device = !!size; char* mount_opts = (char*)optsarg; char* target = (char*)dir; char* fs = (char*)fsarg; char* source = NULL; char loopname[64]; if (need_loop_device) { memset(loopname, 0, sizeof(loopname)); snprintf(loopname, sizeof(loopname), "/dev/loop%llu", procid); if (setup_loop_device(data, size, loopname, &loopfd) == -1) return -1; source = loopname; } mkdir(target, 0777); char opts[256]; memset(opts, 0, sizeof(opts)); if (strlen(mount_opts) > (sizeof(opts) - 32)) { } strncpy(opts, mount_opts, sizeof(opts) - 32); if (strcmp(fs, "iso9660") == 0) { flags |= MS_RDONLY; } else if (strncmp(fs, "ext", 3) == 0) { bool has_remount_ro = false; char* remount_ro_start = strstr(opts, "errors=remount-ro"); if (remount_ro_start != NULL) { char after = *(remount_ro_start + strlen("errors=remount-ro")); char before = remount_ro_start == opts ? '\0' : *(remount_ro_start - 1); has_remount_ro = ((before == '\0' || before == ',') && (after == '\0' || after == ',')); } if (strstr(opts, "errors=panic") || !has_remount_ro) strcat(opts, ",errors=continue"); } else if (strcmp(fs, "xfs") == 0) { strcat(opts, ",nouuid"); } res = mount(source, target, fs, flags, opts); if (res == -1) { err = errno; goto error_clear_loop; } res = open(target, O_RDONLY | O_DIRECTORY); if (res == -1) { err = errno; goto error_clear_loop; } if (change_dir) { res = chdir(target); if (res == -1) { err = errno; } } error_clear_loop: if (need_loop_device) { ioctl(loopfd, LOOP_CLR_FD, 0); close(loopfd); } errno = err; return res; } #define FS_IOC_SETFLAGS _IOW('f', 2, long) static void remove_dir(const char* dir) { int iter = 0; DIR* dp = 0; retry: while (umount2(dir, MNT_DETACH | UMOUNT_NOFOLLOW) == 0) { } dp = opendir(dir); if (dp == NULL) { if (errno == EMFILE) { exit(1); } exit(1); } struct dirent* ep = 0; while ((ep = readdir(dp))) { if (strcmp(ep->d_name, ".") == 0 || strcmp(ep->d_name, "..") == 0) continue; char filename[FILENAME_MAX]; snprintf(filename, sizeof(filename), "%s/%s", dir, ep->d_name); while (umount2(filename, MNT_DETACH | UMOUNT_NOFOLLOW) == 0) { } struct stat st; if (lstat(filename, &st)) exit(1); if (S_ISDIR(st.st_mode)) { remove_dir(filename); continue; } int i; for (i = 0;; i++) { if (unlink(filename) == 0) break; if (errno == EPERM) { int fd = open(filename, O_RDONLY); if (fd != -1) { long flags = 0; if (ioctl(fd, FS_IOC_SETFLAGS, &flags) == 0) { } close(fd); continue; } } if (errno == EROFS) { break; } if (errno != EBUSY || i > 100) exit(1); if (umount2(filename, MNT_DETACH | UMOUNT_NOFOLLOW)) exit(1); } } closedir(dp); for (int i = 0;; i++) { if (rmdir(dir) == 0) break; if (i < 100) { if (errno == EPERM) { int fd = open(dir, O_RDONLY); if (fd != -1) { long flags = 0; if (ioctl(fd, FS_IOC_SETFLAGS, &flags) == 0) { } close(fd); continue; } } if (errno == EROFS) { break; } if (errno == EBUSY) { if (umount2(dir, MNT_DETACH | UMOUNT_NOFOLLOW)) exit(1); continue; } if (errno == ENOTEMPTY) { if (iter < 100) { iter++; goto retry; } } } exit(1); } } 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 reset_loop() { char buf[64]; snprintf(buf, sizeof(buf), "/dev/loop%llu", procid); int loopfd = open(buf, O_RDWR); if (loopfd != -1) { ioctl(loopfd, LOOP_CLR_FD, 0); close(loopfd); } } static void setup_test() { prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0); setpgrp(); write_file("/proc/self/oom_score_adj", "1000"); if (symlink("/dev/binderfs", "./binderfs")) { } } 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 < 9; 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++) { char cwdbuf[32]; sprintf(cwdbuf, "./%d", iter); if (mkdir(cwdbuf, 0777)) exit(1); reset_loop(); int pid = fork(); if (pid < 0) exit(1); if (pid == 0) { if (chdir(cwdbuf)) exit(1); 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; } remove_dir(cwdbuf); } } uint64_t r[2] = {0xffffffffffffffff, 0xffffffffffffffff}; void execute_call(int call) { intptr_t res = 0; switch (call) { case 0: NONFAILING(memcpy((void*)0x20001040, "./file2\000", 8)); NONFAILING(syz_mount_image(/*fs=*/0, /*dir=*/0x20001040, /*flags=*/0, /*opts=*/0, /*chdir=*/0, /*size=*/0, /*img=*/0)); break; case 1: NONFAILING(memcpy((void*)0x20002080, "./file0\000", 8)); NONFAILING(syz_mount_image(/*fs=*/0, /*dir=*/0x20002080, /*flags=*/0, /*opts=*/0, /*chdir=*/0, /*size=*/0, /*img=*/0)); break; case 2: NONFAILING(memcpy((void*)0x20000040, "./file0\000", 8)); NONFAILING(memcpy((void*)0x20000000, "overlay\000", 8)); NONFAILING(memcpy((void*)0x20000100, "workdir", 7)); NONFAILING(*(uint8_t*)0x20000107 = 0x3d); NONFAILING(memcpy((void*)0x20000108, "./file0", 7)); NONFAILING(*(uint8_t*)0x2000010f = 0x2c); NONFAILING(memcpy((void*)0x20000110, "lowerdir", 8)); NONFAILING(*(uint8_t*)0x20000118 = 0x3d); NONFAILING(memset((void*)0x20000119, 46, 1)); NONFAILING(*(uint8_t*)0x2000011a = 0x2c); NONFAILING(memcpy((void*)0x2000011b, "upperdir", 8)); NONFAILING(*(uint8_t*)0x20000123 = 0x3d); NONFAILING(memcpy((void*)0x20000124, "./file2", 7)); NONFAILING(*(uint8_t*)0x2000012b = 0x2c); NONFAILING(*(uint8_t*)0x2000012c = 0x2c); syscall(__NR_mount, /*src=*/0ul, /*dst=*/0x20000040ul, /*type=*/0x20000000ul, /*flags=*/0ul, /*opts=*/0x20000100ul); break; case 3: NONFAILING(memcpy((void*)0x20000040, "./file1\000", 8)); res = syscall(__NR_openat, /*fd=*/0xffffff9c, /*file=*/0x20000040ul, /*flags=*/0xa42ul, /*mode=*/0ul); if (res != -1) r[0] = res; break; case 4: NONFAILING(*(uint32_t*)0x20000000 = 0xfffffe98); NONFAILING(*(uint8_t*)0x20000004 = 0x21); NONFAILING(*(uint16_t*)0x20000005 = 0); syscall(__NR_write, /*fd=*/r[0], /*data=*/0x20000000ul, /*size=*/0x800600ul); break; case 5: NONFAILING(memcpy((void*)0x20000080, "./file1\000", 8)); syscall(__NR_openat, /*fd=*/0xffffff9cul, /*file=*/0x20000080ul, /*flags=*/0x20200ul, /*mode=*/0ul); break; case 6: NONFAILING(*(uint32_t*)0x20000300 = 0x18); NONFAILING(*(uint8_t*)0x20000304 = 0xf); NONFAILING(*(uint16_t*)0x20000305 = 0); NONFAILING(*(uint8_t*)0x20000307 = 0); NONFAILING(*(uint32_t*)0x20000308 = 0); NONFAILING(*(uint64_t*)0x2000030c = 0); NONFAILING(*(uint32_t*)0x20000314 = 0); syscall(__NR_write, /*fd=*/r[0], /*data=*/0x20000300ul, /*size=*/0x18ul); break; case 7: NONFAILING(memcpy((void*)0x200000c0, "./file0\000", 8)); res = syscall(__NR_openat, /*fd=*/0xffffffffffffff9cul, /*file=*/0x200000c0ul, /*flags=*/0ul, /*mode=*/0ul); if (res != -1) r[1] = res; break; case 8: NONFAILING(memcpy((void*)0x200000c0, "./file1\000", 8)); syscall(__NR_fchmodat, /*dirfd=*/r[1], /*file=*/0x200000c0ul, /*mode=*/0xd00ul); 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); install_segv_handler(); for (procid = 0; procid < 4; procid++) { if (fork() == 0) { use_temporary_dir(); loop(); } } sleep(1000000); return 0; } =* repro.txt =* syz_mount_image$fuse(0x0, &(0x7f0000001040)='./file2\x00', 0x0, 0x0, 0x0, 0x0, 0x0) syz_mount_image$fuse(0x0, &(0x7f0000002080)='./file0\x00', 0x0, 0x0, 0x0, 0x0, 0x0) mount$overlay(0x0, &(0x7f0000000040)='./file0\x00', &(0x7f0000000000), 0x0, &(0x7f0000000100)={[{@workdir={'workdir', 0x3d, './file0'}}, {@lowerdir={'lowerdir', 0x3d, '.'}}, {@upperdir={'upperdir', 0x3d, './file2'}}], [], 0x2c}) r0 = openat(0xffffffffffffff9c, &(0x7f0000000040)='./file1\x00', 0xa42, 0x0) write$P9_RXATTRCREATE(r0, &(0x7f0000000000)={0xfffffffffffffe98}, 0x800600) openat$dir(0xffffff9c, &(0x7f0000000080)='./file1\x00', 0x20200, 0x0) write$P9_RLCREATE(r0, &(0x7f0000000300)={0x18}, 0x18) r1 = openat$dir(0xffffffffffffff9c, &(0x7f00000000c0)='./file0\x00', 0x0, 0x0) fchmodat(r1, &(0x7f00000000c0)='./file1\x00', 0xd00) See aslo https://gist.github.com/xrivendell7/86a9486e8e1e703c4f4453abec064fb5 I hope it helps. Best regards. xingwei Lee
