Messages in this thread | | | From | Andrey Konovalov <> | Date | Fri, 28 Apr 2017 15:08:44 +0200 | Subject | net/ipv6: warning in inet6_ifa_finish_destroy |
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Hi,
I've got the following error report while fuzzing the kernel with syzkaller.
On commit 5a7ad1146caa895ad718a534399e38bd2ba721b7 (4.11-rc8).
C reproducer and .config are attached. It takes 1-2 minutes of running the reproducer to trigger the issue.
------------[ cut here ]------------ WARNING: CPU: 0 PID: 21 at net/ipv6/addrconf.c:894 inet6_ifa_finish_destroy+0x12e/0x190 Modules linked in: CPU: 0 PID: 21 Comm: kworker/0:1 Not tainted 4.11.0-rc8+ #296 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 Workqueue: ipv6_addrconf addrconf_dad_work Call Trace: __dump_stack lib/dump_stack.c:16 dump_stack+0x292/0x398 lib/dump_stack.c:52 __warn+0x19f/0x1e0 kernel/panic.c:549 warn_slowpath_null+0x2c/0x40 kernel/panic.c:584 inet6_ifa_finish_destroy+0x12e/0x190 c:894 in6_ifa_put ./include/net/addrconf.h:330 addrconf_dad_work+0x4e9/0x1040 net/ipv6/addrconf.c:3963 process_one_work+0xc04/0x1c10 kernel/workqueue.c:2097 worker_thread+0x223/0x19c0 kernel/workqueue.c:2231 kthread+0x35e/0x430 kernel/kthread.c:231 ret_from_fork+0x31/0x40 arch/x86/entry/entry_64.S:430 ---[ end trace 64f7dae275ec6e42 ]--- IPv6: Freeing alive inet6 address ffff88006383a000 [unhandled content-type:application/octet-stream]// autogenerated by syzkaller (http://github.com/google/syzkaller)
#ifndef __NR_mmap #define __NR_mmap 9 #endif #ifndef __NR_socket #define __NR_socket 41 #endif #ifndef __NR_ioctl #define __NR_ioctl 16 #endif
#define _GNU_SOURCE
#include <sys/ioctl.h> #include <sys/mman.h> #include <sys/mount.h> #include <sys/prctl.h> #include <sys/resource.h> #include <sys/socket.h> #include <sys/stat.h> #include <sys/syscall.h> #include <sys/time.h> #include <sys/types.h> #include <sys/wait.h>
#include <linux/capability.h> #include <linux/if.h> #include <linux/if_tun.h> #include <linux/kvm.h> #include <linux/sched.h> #include <net/if_arp.h>
#include <assert.h> #include <dirent.h> #include <errno.h> #include <fcntl.h> #include <grp.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 <unistd.h>
const int kFailStatus = 67; const int kErrorStatus = 68; const int kRetryStatus = 69;
__attribute__((noreturn)) void doexit(int status) { volatile unsigned i; syscall(__NR_exit_group, status); for (i = 0;; i++) { } }
__attribute__((noreturn)) void fail(const char* msg, ...) { int e = errno; fflush(stdout); va_list args; va_start(args, msg); vfprintf(stderr, msg, args); va_end(args); fprintf(stderr, " (errno %d)\n", e); doexit((e == ENOMEM || e == EAGAIN) ? kRetryStatus : kFailStatus); }
__attribute__((noreturn)) void exitf(const char* msg, ...) { int e = errno; fflush(stdout); va_list args; va_start(args, msg); vfprintf(stderr, msg, args); va_end(args); fprintf(stderr, " (errno %d)\n", e); doexit(kRetryStatus); }
static int flag_debug;
void debug(const char* msg, ...) { if (!flag_debug) return; va_list args; va_start(args, msg); vfprintf(stdout, msg, args); va_end(args); fflush(stdout); }
__thread int skip_segv; __thread jmp_buf segv_env;
static void segv_handler(int sig, siginfo_t* info, void* uctx) { uintptr_t addr = (uintptr_t)info->si_addr; const uintptr_t prog_start = 1 << 20; const uintptr_t prog_end = 100 << 20; if (__atomic_load_n(&skip_segv, __ATOMIC_RELAXED) && (addr < prog_start || addr > prog_end)) { debug("SIGSEGV on %p, skipping\n", addr); _longjmp(segv_env, 1); } debug("SIGSEGV on %p, exiting\n", addr); doexit(sig); for (;;) { } }
static void install_segv_handler() { struct sigaction sa; 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(...) \ { \ __atomic_fetch_add(&skip_segv, 1, __ATOMIC_SEQ_CST); \ if (_setjmp(segv_env) == 0) { \ __VA_ARGS__; \ } \ __atomic_fetch_sub(&skip_segv, 1, __ATOMIC_SEQ_CST); \ }
#define BITMASK_LEN(type, bf_len) (type)((1ull << (bf_len)) - 1)
#define BITMASK_LEN_OFF(type, bf_off, bf_len) \ (type)(BITMASK_LEN(type, (bf_len)) << (bf_off))
#define STORE_BY_BITMASK(type, addr, val, bf_off, bf_len) \ if ((bf_off) == 0 && (bf_len) == 0) { \ *(type*)(addr) = (type)(val); \ } else { \ type new_val = *(type*)(addr); \ new_val &= ~BITMASK_LEN_OFF(type, (bf_off), (bf_len)); \ new_val |= ((type)(val)&BITMASK_LEN(type, (bf_len))) << (bf_off); \ *(type*)(addr) = new_val; \ }
struct csum_inet { uint32_t acc; };
void csum_inet_init(struct csum_inet* csum) { csum->acc = 0; }
void csum_inet_update(struct csum_inet* csum, const uint8_t* data, size_t length) { if (length == 0) return;
size_t i; for (i = 0; i < length - 1; i += 2) csum->acc += *(uint16_t*)&data[i];
if (length & 1) csum->acc += (uint16_t)data[length - 1];
while (csum->acc > 0xffff) csum->acc = (csum->acc & 0xffff) + (csum->acc >> 16); }
uint16_t csum_inet_digest(struct csum_inet* csum) { return ~csum->acc; }
static uintptr_t execute_syscall(int nr, uintptr_t a0, uintptr_t a1, uintptr_t a2, uintptr_t a3, uintptr_t a4, uintptr_t a5, uintptr_t a6, uintptr_t a7, uintptr_t a8) { switch (nr) { default: return syscall(nr, a0, a1, a2, a3, a4, a5); } }
static void setup_main_process() { 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); install_segv_handler();
char tmpdir_template[] = "./syzkaller.XXXXXX"; char* tmpdir = mkdtemp(tmpdir_template); if (!tmpdir) fail("failed to mkdtemp"); if (chmod(tmpdir, 0777)) fail("failed to chmod"); if (chdir(tmpdir)) fail("failed to chdir"); }
static void loop();
static void sandbox_common() { prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0); setpgrp(); setsid();
struct rlimit rlim; rlim.rlim_cur = rlim.rlim_max = 128 << 20; setrlimit(RLIMIT_AS, &rlim); rlim.rlim_cur = rlim.rlim_max = 1 << 20; setrlimit(RLIMIT_FSIZE, &rlim); rlim.rlim_cur = rlim.rlim_max = 1 << 20; setrlimit(RLIMIT_STACK, &rlim); rlim.rlim_cur = rlim.rlim_max = 0; setrlimit(RLIMIT_CORE, &rlim);
unshare(CLONE_NEWNS); unshare(CLONE_NEWIPC); unshare(CLONE_IO); }
static int real_uid; static int real_gid; static int epid; static bool etun; __attribute__((aligned(64 << 10))) static char sandbox_stack[1 << 20];
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) { close(fd); return false; } close(fd); return true; }
static int namespace_sandbox_proc(void* arg) { sandbox_common();
write_file("/proc/self/setgroups", "deny"); if (!write_file("/proc/self/uid_map", "0 %d 1\n", real_uid)) fail("write of /proc/self/uid_map failed"); if (!write_file("/proc/self/gid_map", "0 %d 1\n", real_gid)) fail("write of /proc/self/gid_map failed");
if (mkdir("./syz-tmp", 0777)) fail("mkdir(syz-tmp) failed"); if (mount("", "./syz-tmp", "tmpfs", 0, NULL)) fail("mount(tmpfs) failed"); if (mkdir("./syz-tmp/newroot", 0777)) fail("mkdir failed"); if (mkdir("./syz-tmp/newroot/dev", 0700)) fail("mkdir failed"); if (mount("/dev", "./syz-tmp/newroot/dev", NULL, MS_BIND | MS_REC | MS_PRIVATE, NULL)) fail("mount(dev) failed"); if (mkdir("./syz-tmp/pivot", 0777)) fail("mkdir failed"); if (syscall(SYS_pivot_root, "./syz-tmp", "./syz-tmp/pivot")) { debug("pivot_root failed"); if (chdir("./syz-tmp")) fail("chdir failed"); } else { if (chdir("/")) fail("chdir failed"); if (umount2("./pivot", MNT_DETACH)) fail("umount failed"); } if (chroot("./newroot")) fail("chroot failed"); if (chdir("/")) fail("chdir failed");
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)) fail("capget failed"); cap_data[0].effective &= ~(1 << CAP_SYS_PTRACE); cap_data[0].permitted &= ~(1 << CAP_SYS_PTRACE); cap_data[0].inheritable &= ~(1 << CAP_SYS_PTRACE); if (syscall(SYS_capset, &cap_hdr, &cap_data)) fail("capset failed");
loop(); doexit(1); }
static int do_sandbox_namespace(int executor_pid, bool enable_tun) { real_uid = getuid(); real_gid = getgid(); epid = executor_pid; etun = enable_tun; mprotect(sandbox_stack, 4096, PROT_NONE); return clone( namespace_sandbox_proc, &sandbox_stack[sizeof(sandbox_stack) - 64], CLONE_NEWUSER | CLONE_NEWPID | CLONE_NEWUTS | CLONE_NEWNET, NULL); }
static void remove_dir(const char* dir) { DIR* dp; struct dirent* ep; int iter = 0; retry: dp = opendir(dir); if (dp == NULL) { if (errno == EMFILE) { exitf("opendir(%s) failed due to NOFILE, exiting"); } exitf("opendir(%s) failed", dir); } 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); struct stat st; if (lstat(filename, &st)) exitf("lstat(%s) failed", filename); if (S_ISDIR(st.st_mode)) { remove_dir(filename); continue; } int i; for (i = 0;; i++) { debug("unlink(%s)\n", filename); if (unlink(filename) == 0) break; if (errno == EROFS) { debug("ignoring EROFS\n"); break; } if (errno != EBUSY || i > 100) exitf("unlink(%s) failed", filename); debug("umount(%s)\n", filename); if (umount2(filename, MNT_DETACH)) exitf("umount(%s) failed", filename); } } closedir(dp); int i; for (i = 0;; i++) { debug("rmdir(%s)\n", dir); if (rmdir(dir) == 0) break; if (i < 100) { if (errno == EROFS) { debug("ignoring EROFS\n"); break; } if (errno == EBUSY) { debug("umount(%s)\n", dir); if (umount2(dir, MNT_DETACH)) exitf("umount(%s) failed", dir); continue; } if (errno == ENOTEMPTY) { if (iter < 100) { iter++; goto retry; } } } exitf("rmdir(%s) failed", dir); } }
static uint64_t current_time_ms() { struct timespec ts;
if (clock_gettime(CLOCK_MONOTONIC, &ts)) fail("clock_gettime failed"); return (uint64_t)ts.tv_sec * 1000 + (uint64_t)ts.tv_nsec / 1000000; }
static void test();
void loop() { int iter; for (iter = 0;; iter++) { char cwdbuf[256]; sprintf(cwdbuf, "./%d", iter); if (mkdir(cwdbuf, 0777)) fail("failed to mkdir"); int pid = fork(); if (pid < 0) fail("clone failed"); if (pid == 0) { prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0); setpgrp(); if (chdir(cwdbuf)) fail("failed to chdir"); test(); doexit(0); } int status = 0; uint64_t start = current_time_ms(); for (;;) { int res = waitpid(-1, &status, __WALL | WNOHANG); if (res == pid) break; usleep(1000); if (current_time_ms() - start > 5 * 1000) { kill(-pid, SIGKILL); kill(pid, SIGKILL); while (waitpid(-1, &status, __WALL) != pid) { } break; } } remove_dir(cwdbuf); } }
long r[61]; void* thr(void* arg) { switch ((long)arg) { case 0: r[0] = execute_syscall(__NR_mmap, 0x20000000ul, 0x8000ul, 0x3ul, 0x32ul, 0xfffffffffffffffful, 0x0ul, 0, 0, 0); break; case 1: r[1] = execute_syscall(__NR_socket, 0xaul, 0x5ul, 0x0ul, 0, 0, 0, 0, 0, 0); break; case 2: NONFAILING(memcpy((void*)0x20005fd8, "\x69\x70\x36\x74\x6e\x6c\x30\x00\x00\x00\x00\x00" "\x00\x00\x00\x00", 16)); NONFAILING(*(uint32_t*)0x20005fe8 = (uint32_t)0x0); NONFAILING(*(uint8_t*)0x20005fec = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x20005fed = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x20005fee = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x20005fef = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x20005ff0 = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x20005ff1 = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x20005ff2 = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x20005ff3 = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x20005ff4 = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x20005ff5 = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x20005ff6 = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x20005ff7 = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x20005ff8 = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x20005ff9 = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x20005ffa = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x20005ffb = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x20005ffc = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x20005ffd = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x20005ffe = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x20005fff = (uint8_t)0x0); r[24] = execute_syscall(__NR_ioctl, r[1], 0x8933ul, 0x20005fd8ul, 0, 0, 0, 0, 0, 0); if (r[24] != -1) NONFAILING(r[25] = *(uint32_t*)0x20005fe8); break; case 3: NONFAILING(*(uint8_t*)0x20001000 = (uint8_t)0xfd); NONFAILING(*(uint8_t*)0x20001001 = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x20001002 = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x20001003 = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x20001004 = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x20001005 = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x20001006 = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x20001007 = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x20001008 = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x20001009 = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x2000100a = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x2000100b = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x2000100c = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x2000100d = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x2000100e = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x2000100f = (uint8_t)0xbb); NONFAILING(*(uint32_t*)0x20001010 = (uint32_t)0x1); NONFAILING(*(uint32_t*)0x20001014 = r[25]); r[44] = execute_syscall(__NR_ioctl, r[1], 0x8916ul, 0x20001000ul, 0, 0, 0, 0, 0, 0); break; case 4: NONFAILING(memcpy((void*)0x20000000, "\x69\x70\x36\x74\x6e\x6c\x30\x00\x00\x00\x00\x00" "\x00\x00\x00\x00", 16)); NONFAILING(*(uint16_t*)0x20000010 = (uint16_t)0x4001); r[47] = execute_syscall(__NR_ioctl, r[1], 0x8914ul, 0x20000000ul, 0, 0, 0, 0, 0, 0); break; case 5: NONFAILING(memcpy((void*)0x20000000, "\x69\x70\x36\x74\x6e\x6c\x30\x00\x00\x00\x00\x00" "\x00\x00\x00\x00", 16)); NONFAILING(*(uint16_t*)0x20000010 = (uint16_t)0x2); NONFAILING(*(uint16_t*)0x20000012 = (uint16_t)0x204e); NONFAILING(*(uint32_t*)0x20000014 = (uint32_t)0x0); NONFAILING(*(uint8_t*)0x20000018 = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x20000019 = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x2000001a = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x2000001b = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x2000001c = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x2000001d = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x2000001e = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x2000001f = (uint8_t)0x0); r[60] = execute_syscall(__NR_ioctl, r[1], 0x8914ul, 0x20000000ul, 0, 0, 0, 0, 0, 0); break; } return 0; }
void test() { long i; pthread_t th[12];
memset(r, -1, sizeof(r)); srand(getpid()); for (i = 0; i < 6; i++) { pthread_create(&th[i], 0, thr, (void*)i); usleep(10000); } for (i = 0; i < 6; i++) { pthread_create(&th[6 + i], 0, thr, (void*)i); if (rand() % 2) usleep(rand() % 10000); } usleep(100000); }
int main() { int i; for (i = 0; i < 8; i++) { if (fork() == 0) { setup_main_process(); int pid = do_sandbox_namespace(i, false); int status = 0; while (waitpid(pid, &status, __WALL) != pid) { } return 0; } } sleep(1000000); return 0; }
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