BUG: unable to handle kernel paging request in fuse_copy_do

From: xingwei lee
Date: Thu Mar 21 2024 - 03:52:51 EST

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Hello I found a bug titled "BUG: unable to handle kernel paging
request in fuse_copy_do” with modified syzkaller, and maybe it is
related to fs/fuse.
I also confirmed in the latest upstream.

If you fix this issue, please add the following tag to the commit:
Reported-by: xingwei lee <xrivendell7@xxxxxxxxx>
Reported-by: yue sun <samsun1006219@xxxxxxxxx>

kernel: upstream 23956900041d968f9ad0f30db6dede4daccd7aa9
kernel config: https://syzkaller.appspot.com/text?tag=KernelConfig&x=9f47e8dfa53b0b11
with KASAN enabled
compiler: gcc (Debian 12.2.0-14) 12.2.0

BUG: unable to handle kernel paging request in fuse_copy_do
UDPLite: UDP-Lite is deprecated and scheduled to be removed in 2025,
please contact the netdev mailing list
BUG: unable to handle page fault for address: ffff88802c29c000
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 13001067 P4D 13001067 PUD 13002067 PMD 24c8d063 PTE 800fffffd3d63060
Oops: 0000 [#1] PREEMPT SMP KASAN NOPTI
CPU: 1 PID: 8221 Comm: 1e9 Not tainted 6.8.0-05202-g9187210eee7d-dirty #21
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
1.16.2-1.fc38 04/01/2014
RIP: 0010:memcpy+0xc/0x20 arch/x86/lib/memcpy_64.S:38
Code: 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 90 90 90 90 90 90 90
90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 48 89 f80
RSP: 0018:ffffc9001065f9c8 EFLAGS: 00010246
RAX: ffffc9001065fb10 RBX: ffffc9001065fc78 RCX: 0000000000000010
RDX: 0000000000000010 RSI: ffff88802c29c000 RDI: ffffc9001065fb10
RBP: 0000000000000010 R08: ffff88802c29c000 R09: 0000000000000001
R10: ffffffff8ea82ed7 R11: ffffc9001065fd98 R12: ffffc9001065fac0
R13: 0000000000000010 R14: ffffc9001065faf0 R15: ffffc9001065fcbc
FS: 000000000f82d480(0000) GS:ffff88823bc00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffff88802c29c000 CR3: 000000002dd7c000 CR4: 0000000000750ef0
PKRU: 55555554
Call Trace:
<TASK>
fuse_copy_do+0x152/0x340 fs/fuse/dev.c:758
fuse_copy_one fs/fuse/dev.c:1007 [inline]
fuse_dev_do_write+0x1df/0x26a0 fs/fuse/dev.c:1863
fuse_dev_write+0x129/0x1b0 fs/fuse/dev.c:1960
call_write_iter include/linux/fs.h:2108 [inline]
new_sync_write fs/read_write.c:497 [inline]
vfs_write+0x62e/0x10a0 fs/read_write.c:590
ksys_write+0xf6/0x1d0 fs/read_write.c:643
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0x7c/0x1d0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x6c/0x74

=* repro.c =*
#define _GNU_SOURCE

#include <dirent.h>
#include <endian.h>
#include <errno.h>
#include <fcntl.h>
#include <setjmp.h>
#include <signal.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/prctl.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <time.h>
#include <unistd.h>

#ifndef __NR_memfd_secret
#define __NR_memfd_secret 447
#endif

static __thread int clone_ongoing;
static __thread int skip_segv;
static __thread jmp_buf segv_env;

static void segv_handler(int sig, siginfo_t* info, void* ctx) {
if (__atomic_load_n(&clone_ongoing, __ATOMIC_RELAXED) != 0) {
exit(sig);
}
uintptr_t addr = (uintptr_t)info->si_addr;
const uintptr_t prog_start = 1 << 20;
const uintptr_t prog_end = 100 << 20;
int skip = __atomic_load_n(&skip_segv, __ATOMIC_RELAXED) != 0;
int valid = addr < prog_start || addr > prog_end;
if (skip && valid) {
_longjmp(segv_env, 1);
}
exit(sig);
}

static void install_segv_handler(void) {
struct sigaction sa;
memset(&sa, 0, sizeof(sa));
sa.sa_handler = SIG_IGN;
syscall(SYS_rt_sigaction, 0x20, &sa, NULL, 8);
syscall(SYS_rt_sigaction, 0x21, &sa, NULL, 8);
memset(&sa, 0, sizeof(sa));
sa.sa_sigaction = segv_handler;
sa.sa_flags = SA_NODEFER | SA_SIGINFO;
sigaction(SIGSEGV, &sa, NULL);
sigaction(SIGBUS, &sa, NULL);
}

#define NONFAILING(...) \
({ \
int ok = 1; \
__atomic_fetch_add(&skip_segv, 1, __ATOMIC_SEQ_CST); \
if (_setjmp(segv_env) == 0) { \
__VA_ARGS__; \
} else \
ok = 0; \
__atomic_fetch_sub(&skip_segv, 1, __ATOMIC_SEQ_CST); \
ok; \
})

static void sleep_ms(uint64_t ms) {
usleep(ms * 1000);
}

static uint64_t current_time_ms(void) {
struct timespec ts;
if (clock_gettime(CLOCK_MONOTONIC, &ts))
exit(1);
return (uint64_t)ts.tv_sec * 1000 + (uint64_t)ts.tv_nsec / 1000000;
}

static bool write_file(const char* file, const char* what, ...) {
char buf[1024];
va_list args;
va_start(args, what);
vsnprintf(buf, sizeof(buf), what, args);
va_end(args);
buf[sizeof(buf) - 1] = 0;
int len = strlen(buf);
int fd = open(file, O_WRONLY | O_CLOEXEC);
if (fd == -1)
return false;
if (write(fd, buf, len) != len) {
int err = errno;
close(fd);
errno = err;
return false;
}
close(fd);
return true;
}

static void kill_and_wait(int pid, int* status) {
kill(-pid, SIGKILL);
kill(pid, SIGKILL);
for (int i = 0; i < 100; i++) {
if (waitpid(-1, status, WNOHANG | __WALL) == pid)
return;
usleep(1000);
}
DIR* dir = opendir("/sys/fs/fuse/connections");
if (dir) {
for (;;) {
struct dirent* ent = readdir(dir);
if (!ent)
break;
if (strcmp(ent->d_name, ".") == 0 || strcmp(ent->d_name, "..") == 0)
continue;
char abort[300];
snprintf(abort, sizeof(abort), "/sys/fs/fuse/connections/%s/abort",
ent->d_name);
int fd = open(abort, O_WRONLY);
if (fd == -1) {
continue;
}
if (write(fd, abort, 1) < 0) {
}
close(fd);
}
closedir(dir);
} else {
}
while (waitpid(-1, status, __WALL) != pid) {
}
}

static void setup_test() {
prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0);
setpgrp();
write_file("/proc/self/oom_score_adj", "1000");
}

static void execute_one(void);

#define WAIT_FLAGS __WALL

static void loop(void) {
int iter = 0;
for (;; iter++) {
int pid = fork();
if (pid < 0)
exit(1);
if (pid == 0) {
setup_test();
execute_one();
exit(0);
}
int status = 0;
uint64_t start = current_time_ms();
for (;;) {
if (waitpid(-1, &status, WNOHANG | WAIT_FLAGS) == pid)
break;
sleep_ms(1);
if (current_time_ms() - start < 5000)
continue;
kill_and_wait(pid, &status);
break;
}
}
}

uint64_t r[3] = {0xffffffffffffffff, 0xffffffffffffffff, 0xffffffffffffffff};

void execute_one(void) {
intptr_t res = 0;
NONFAILING(memcpy((void*)0x20002040, "./file0\000", 8));
syscall(__NR_mkdirat, /*fd=*/0xffffff9c, /*path=*/0x20002040ul, /*mode=*/0ul);
NONFAILING(memcpy((void*)0x20002080, "/dev/fuse\000", 10));
res = syscall(__NR_openat, /*fd=*/0xffffffffffffff9cul, /*file=*/0x20002080ul,
/*flags=*/2ul, /*mode=*/0ul);
if (res != -1)
r[0] = res;
NONFAILING(memcpy((void*)0x200020c0, "./file0\000", 8));
NONFAILING(memcpy((void*)0x20002100, "fuse\000", 5));
NONFAILING(memcpy((void*)0x20002140, "fd", 2));
NONFAILING(*(uint8_t*)0x20002142 = 0x3d);
NONFAILING(sprintf((char*)0x20002143, "0x%016llx", (long long)r[0]));
NONFAILING(*(uint8_t*)0x20002155 = 0x2c);
NONFAILING(memcpy((void*)0x20002156, "rootmode", 8));
NONFAILING(*(uint8_t*)0x2000215e = 0x3d);
NONFAILING(sprintf((char*)0x2000215f, "%023llo", (long long)0x4000));
NONFAILING(*(uint8_t*)0x20002176 = 0x2c);
NONFAILING(memcpy((void*)0x20002177, "user_id", 7));
NONFAILING(*(uint8_t*)0x2000217e = 0x3d);
NONFAILING(sprintf((char*)0x2000217f, "%020llu", (long long)0));
NONFAILING(*(uint8_t*)0x20002193 = 0x2c);
NONFAILING(memcpy((void*)0x20002194, "group_id", 8));
NONFAILING(*(uint8_t*)0x2000219c = 0x3d);
NONFAILING(sprintf((char*)0x2000219d, "%020llu", (long long)0));
NONFAILING(*(uint8_t*)0x200021b1 = 0x2c);
NONFAILING(*(uint8_t*)0x200021b2 = 0);
syscall(__NR_mount, /*src=*/0ul, /*dst=*/0x200020c0ul, /*type=*/0x20002100ul,
/*flags=*/0ul, /*opts=*/0x20002140ul);
res = syscall(__NR_memfd_secret, /*flags=*/0ul);
if (res != -1)
r[1] = res;
syscall(__NR_mmap, /*addr=*/0x20000000ul, /*len=*/0xb36000ul,
/*prot=PROT_GROWSUP|PROT_READ*/ 0x2000001ul,
/*flags=MAP_STACK|MAP_POPULATE|MAP_FIXED|MAP_SHARED*/ 0x28011ul,
/*fd=*/r[1], /*offset=*/0ul);
syscall(__NR_ftruncate, /*fd=*/r[1], /*len=*/7ul);
res = syscall(__NR_socket, /*domain=*/2ul, /*type=*/2ul, /*proto=*/0x88);
if (res != -1)
r[2] = res;
NONFAILING(*(uint32_t*)0x20000280 = 0);
syscall(__NR_getsockopt, /*fd=*/r[2], /*level=*/1, /*optname=*/0x11,
/*optval=*/0ul, /*optlen=*/0x20000280ul);
NONFAILING(*(uint32_t*)0x20000000 = 0x50);
NONFAILING(*(uint32_t*)0x20000004 = 0);
NONFAILING(*(uint64_t*)0x20000008 = 0);
NONFAILING(*(uint32_t*)0x20000010 = 7);
NONFAILING(*(uint32_t*)0x20000014 = 0x27);
NONFAILING(*(uint32_t*)0x20000018 = 0);
NONFAILING(*(uint32_t*)0x2000001c = 0);
NONFAILING(*(uint16_t*)0x20000020 = 0);
NONFAILING(*(uint16_t*)0x20000022 = 0);
NONFAILING(*(uint32_t*)0x20000024 = 0);
NONFAILING(*(uint32_t*)0x20000028 = 0);
NONFAILING(*(uint16_t*)0x2000002c = 0);
NONFAILING(*(uint16_t*)0x2000002e = 0);
NONFAILING(memset((void*)0x20000030, 0, 32));
syscall(__NR_write, /*fd=*/r[0], /*arg=*/0x20000000ul, /*len=*/0x50ul);
}
int main(void) {
syscall(__NR_mmap, /*addr=*/0x1ffff000ul, /*len=*/0x1000ul, /*prot=*/0ul,
/*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/ 0x32ul, /*fd=*/-1,
/*offset=*/0ul);
syscall(__NR_mmap, /*addr=*/0x20000000ul, /*len=*/0x1000000ul,
/*prot=PROT_WRITE|PROT_READ|PROT_EXEC*/ 7ul,
/*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/ 0x32ul, /*fd=*/-1,
/*offset=*/0ul);
syscall(__NR_mmap, /*addr=*/0x21000000ul, /*len=*/0x1000ul, /*prot=*/0ul,
/*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/ 0x32ul, /*fd=*/-1,
/*offset=*/0ul);
install_segv_handler();
loop();
return 0;
}

=* repro.txt =*
mkdirat(0xffffffffffffff9c, &(0x7f0000002040)='./file0\x00', 0x0)
r0 = openat$fuse(0xffffffffffffff9c, &(0x7f0000002080), 0x2, 0x0)
mount$fuse(0x0, &(0x7f00000020c0)='./file0\x00', &(0x7f0000002100),
0x0, &(0x7f0000002140)={{'fd', 0x3d, r0}, 0x2c, {'rootmode', 0x3d,
0x4000}})
r1 = memfd_secret(0x0)
mmap(&(0x7f0000000000/0xb36000)=nil, 0xb36000, 0x2000001, 0x28011, r1, 0x0)
ftruncate(r1, 0x7)
r2 = socket$inet_udplite(0x2, 0x2, 0x88)
getsockopt$sock_cred(r2, 0x1, 0x11, 0x0, &(0x7f0000000280))
write$FUSE_INIT(r0, &(0x7f0000000000)={0x50}, 0x50)

see aslo https://gist.github.com/xrivendell7/961be96ae091c9671bb56efea902cec4.

I hope it helps.
best regards.
xingwei Lee

Next message: Liuye: "答复: [PATCH V3] kdb: Fix the deadlock issue in KDB debugging."
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