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 <[email protected]>
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 [email protected]
//% 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
On Fri, Feb 2, 2024 at 1:09 PM xingwei lee <[email protected]> wrote:
>
> 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 <[email protected]>
>
> 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.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.
There are no details about how this repro was run like there are in
syzkaller reports , e.g.:
{"threaded":true,"repeat":true,"procs":5,"slowdown":1,...
I assume this was run in concurrent threads that write to a file that
is an underlying
file for some ovl mounts (because they all mount over the same path).
The only way I see this WARN_ON() get hit:
if (WARN_ON_ONCE(pos < 0 || len < 0 || totlen < 0))
return -EIO;
is if len < 0, after a seek over a hole did:
len -= hole_len;
If racing to grow the underlying lower file under overlayfs this might happen -
not sure if this was the case here.
If that happens it falls well under the category of:
https://docs.kernel.org/filesystems/overlayfs.html#changes-to-underlying-filesystems
Perhaps a WARN_ON is a bit too harsh for this case, but since it is
a WARN_ON_ONCE it is not a big issue IMO.
Then again, my analysis may be wrong.
Please check if the assertion is indeed about len < 0
and whether it really did get to be negative after seeking a hole
to an offset beyond the original file size (when copy up started).
Thanks,
Amir.