kernel BUG in fou_build_udp

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 <sched.h>
#include <signal.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mount.h>
#include <sys/prctl.h>
#include <sys/resource.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <time.h>
#include <unistd.h>

#include <linux/capability.h>

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;
}

#define BITMASK(bf_off,bf_len) (((1ull << (bf_len)) - 1) << (bf_off))
#define STORE_BY_BITMASK(type,htobe,addr,val,bf_off,bf_len) *(type*)(addr) = htobe((htobe(*(type*)(addr)) & ~BITMASK((bf_off), (bf_len))) | (((type)(val) << (bf_off)) & BITMASK((bf_off), (bf_len))))

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;
}

#define MAX_FDS 30

static void setup_common()
{
	if (mount(0, "/sys/fs/fuse/connections", "fusectl", 0, 0)) {
	}
}

static void setup_binderfs()
{
	if (mkdir("/dev/binderfs", 0777)) {
	}
	if (mount("binder", "/dev/binderfs", "binder", 0, NULL)) {
	}
	if (symlink("/dev/binderfs", "./binderfs")) {
	}
}

static void loop();

static void sandbox_common()
{
	prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0);
	setsid();
	struct rlimit rlim;
	rlim.rlim_cur = rlim.rlim_max = (200 << 20);
	setrlimit(RLIMIT_AS, &rlim);
	rlim.rlim_cur = rlim.rlim_max = 32 << 20;
	setrlimit(RLIMIT_MEMLOCK, &rlim);
	rlim.rlim_cur = rlim.rlim_max = 136 << 20;
	setrlimit(RLIMIT_FSIZE, &rlim);
	rlim.rlim_cur = rlim.rlim_max = 1 << 20;
	setrlimit(RLIMIT_STACK, &rlim);
	rlim.rlim_cur = rlim.rlim_max = 128 << 20;
	setrlimit(RLIMIT_CORE, &rlim);
	rlim.rlim_cur = rlim.rlim_max = 256;
	setrlimit(RLIMIT_NOFILE, &rlim);
	if (unshare(CLONE_NEWNS)) {
	}
	if (mount(NULL, "/", NULL, MS_REC | MS_PRIVATE, NULL)) {
	}
	if (unshare(CLONE_NEWIPC)) {
	}
	if (unshare(0x02000000)) {
	}
	if (unshare(CLONE_NEWUTS)) {
	}
	if (unshare(CLONE_SYSVSEM)) {
	}
	typedef struct {
		const char* name;
		const char* value;
	} sysctl_t;
	static const sysctl_t sysctls[] = {
	    {"/proc/sys/kernel/shmmax", "16777216"},
	    {"/proc/sys/kernel/shmall", "536870912"},
	    {"/proc/sys/kernel/shmmni", "1024"},
	    {"/proc/sys/kernel/msgmax", "8192"},
	    {"/proc/sys/kernel/msgmni", "1024"},
	    {"/proc/sys/kernel/msgmnb", "1024"},
	    {"/proc/sys/kernel/sem", "1024 1048576 500 1024"},
	};
	unsigned i;
	for (i = 0; i < sizeof(sysctls) / sizeof(sysctls[0]); i++)
		write_file(sysctls[i].name, sysctls[i].value);
}

static int wait_for_loop(int pid)
{
	if (pid < 0)
	exit(1);
	int status = 0;
	while (waitpid(-1, &status, __WALL) != pid) {
	}
	return WEXITSTATUS(status);
}

static void drop_caps(void)
{
	struct __user_cap_header_struct cap_hdr = {};
	struct __user_cap_data_struct cap_data[2] = {};
	cap_hdr.version = _LINUX_CAPABILITY_VERSION_3;
	cap_hdr.pid = getpid();
	if (syscall(SYS_capget, &cap_hdr, &cap_data))
	exit(1);
	const int drop = (1 << CAP_SYS_PTRACE) | (1 << CAP_SYS_NICE);
	cap_data[0].effective &= ~drop;
	cap_data[0].permitted &= ~drop;
	cap_data[0].inheritable &= ~drop;
	if (syscall(SYS_capset, &cap_hdr, &cap_data))
	exit(1);
}

static int do_sandbox_none(void)
{
	if (unshare(CLONE_NEWPID)) {
	}
	int pid = fork();
	if (pid != 0)
		return wait_for_loop(pid);
	setup_common();
	sandbox_common();
	drop_caps();
	if (unshare(CLONE_NEWNET)) {
	}
	write_file("/proc/sys/net/ipv4/ping_group_range", "0 65535");
	setup_binderfs();
	loop();
	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 setup_test()
{
	prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0);
	setpgrp();
	write_file("/proc/self/oom_score_adj", "1000");
}

static void close_fds()
{
	for (int fd = 3; fd < MAX_FDS; fd++)
		close(fd);
}

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();
			close_fds();
			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[4] = {0xffffffffffffffff, 0xffffffffffffffff, 0xffffffffffffffff, 0x0};

void execute_one(void)
{
		intptr_t res = 0;
	res = syscall(__NR_socket, 0xaul, 2ul, 0);
	if (res != -1)
		r[0] = res;
	res = syscall(__NR_socket, 0x10ul, 3ul, 0);
	if (res != -1)
		r[1] = res;
	res = syscall(__NR_socket, 0x10ul, 0x803ul, 0);
	if (res != -1)
		r[2] = res;
*(uint64_t*)0x20000380 = 0;
*(uint32_t*)0x20000388 = 0;
*(uint64_t*)0x20000390 = 0x20000340;
*(uint64_t*)0x20000340 = 0;
*(uint64_t*)0x20000348 = 0x14;
*(uint64_t*)0x20000398 = 1;
*(uint64_t*)0x200003a0 = 0;
*(uint64_t*)0x200003a8 = 0;
*(uint32_t*)0x200003b0 = 0;
	syscall(__NR_sendmsg, r[2], 0x20000380ul, 0ul);
*(uint32_t*)0x200000c0 = 0x14;
	res = syscall(__NR_getsockname, r[2], 0x20000100ul, 0x200000c0ul);
	if (res != -1)
r[3] = *(uint32_t*)0x20000104;
*(uint64_t*)0x20000080 = 0;
*(uint32_t*)0x20000088 = 0;
*(uint64_t*)0x20000090 = 0x20000500;
*(uint64_t*)0x20000500 = 0x20000180;
*(uint32_t*)0x20000180 = 0x60;
*(uint16_t*)0x20000184 = 0x10;
*(uint16_t*)0x20000186 = 0x439;
*(uint32_t*)0x20000188 = 0;
*(uint32_t*)0x2000018c = 0;
*(uint8_t*)0x20000190 = 0;
*(uint8_t*)0x20000191 = 0;
*(uint16_t*)0x20000192 = 0;
*(uint32_t*)0x20000194 = 0;
*(uint32_t*)0x20000198 = 0x9801;
*(uint32_t*)0x2000019c = 0;
*(uint16_t*)0x200001a0 = 0x40;
STORE_BY_BITMASK(uint16_t, , 0x200001a2, 0x12, 0, 14);
STORE_BY_BITMASK(uint16_t, , 0x200001a3, 0, 6, 1);
STORE_BY_BITMASK(uint16_t, , 0x200001a3, 1, 7, 1);
*(uint16_t*)0x200001a4 = 8;
*(uint16_t*)0x200001a6 = 1;
memcpy((void*)0x200001a8, "sit\000", 4);
*(uint16_t*)0x200001ac = 0x34;
STORE_BY_BITMASK(uint16_t, , 0x200001ae, 2, 0, 14);
STORE_BY_BITMASK(uint16_t, , 0x200001af, 0, 6, 1);
STORE_BY_BITMASK(uint16_t, , 0x200001af, 1, 7, 1);
*(uint16_t*)0x200001b0 = 8;
*(uint16_t*)0x200001b2 = 1;
*(uint32_t*)0x200001b4 = r[3];
*(uint16_t*)0x200001b8 = 6;
*(uint16_t*)0x200001ba = 0xf;
*(uint16_t*)0x200001bc = 2;
*(uint16_t*)0x200001c0 = 6;
*(uint16_t*)0x200001c2 = 0x11;
*(uint16_t*)0x200001c4 = htobe16(0x4e21);
*(uint16_t*)0x200001c8 = 6;
*(uint16_t*)0x200001ca = 0x11;
*(uint16_t*)0x200001cc = htobe16(0x4e24);
*(uint16_t*)0x200001d0 = 8;
*(uint16_t*)0x200001d2 = 2;
*(uint8_t*)0x200001d4 = 0xac;
*(uint8_t*)0x200001d5 = 0x14;
*(uint8_t*)0x200001d6 = 0x14;
*(uint8_t*)0x200001d7 = 0x16;
*(uint16_t*)0x200001d8 = 6;
*(uint16_t*)0x200001da = 0x10;
*(uint16_t*)0x200001dc = 0xfff;
*(uint64_t*)0x20000508 = 0x60;
*(uint64_t*)0x20000098 = 1;
*(uint64_t*)0x200000a0 = 0;
*(uint64_t*)0x200000a8 = 0;
*(uint32_t*)0x200000b0 = 0;
	syscall(__NR_sendmsg, r[1], 0x20000080ul, 0x20048894ul);
*(uint64_t*)0x200017c0 = 0x20000040;
*(uint16_t*)0x20000040 = 2;
*(uint16_t*)0x20000042 = htobe16(0x4e20);
*(uint32_t*)0x20000044 = htobe32(0xe0000001);
*(uint32_t*)0x200017c8 = 0x10;
*(uint64_t*)0x200017d0 = 0;
*(uint64_t*)0x200017d8 = 0;
*(uint64_t*)0x200017e0 = 0x20000000;
*(uint64_t*)0x20000000 = 0x1c;
*(uint32_t*)0x20000008 = 0;
*(uint32_t*)0x2000000c = 8;
*(uint32_t*)0x20000010 = r[3];
*(uint32_t*)0x20000014 = htobe32(0);
*(uint8_t*)0x20000018 = 0xac;
*(uint8_t*)0x20000019 = 0x14;
*(uint8_t*)0x2000001a = 0x14;
*(uint8_t*)0x2000001b = 0xbb;
*(uint64_t*)0x200017e8 = 0x20;
*(uint32_t*)0x200017f0 = 0;
*(uint32_t*)0x200017f8 = 0;
	syscall(__NR_sendmmsg, r[0], 0x200017c0ul, 1ul, 0ul);

}
int main(void)
{
		syscall(__NR_mmap, 0x1ffff000ul, 0x1000ul, 0ul, 0x32ul, -1, 0ul);
	syscall(__NR_mmap, 0x20000000ul, 0x1000000ul, 7ul, 0x32ul, -1, 0ul);
	syscall(__NR_mmap, 0x21000000ul, 0x1000ul, 0ul, 0x32ul, -1, 0ul);
			do_sandbox_none();
	return 0;
}