Messages in this thread | | | From | Dmitry Vyukov <> | Date | Fri, 1 Feb 2019 17:48:27 +0100 | Subject | perf_event_open+clone = unkillable process |
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Hello,
The following program creates an unkillable process that eats CPU. /proc/pid/stack is empty, I am not sure what other info I can provide.
Tested is on upstream commit 4aa9fc2a435abe95a1e8d7f8c7b3d6356514b37a. Config is attached.
FTR, generated from the following syzkaller program:
perf_event_open(&(0x7f0000000580)={0x2, 0x70, 0x5c61, 0x2, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, @perf_config_ext}, 0x0, 0xffffffffffffffff, 0xffffffffffffffff, 0x0) clone(0x20002100, 0x0, 0xfffffffffffffffe, 0x0, 0xffffffffffffffff) r0 = gettid() timer_create(0x0, &(0x7f0000000000)={0x0, 0x7, 0x4, @tid=r0}, &(0x7f0000000080)) timer_settime(0x0, 0x3, &(0x7f0000000140)={{0x0, 0x1}, {0x0, 0x1c9c380}}, 0x0)
// autogenerated by syzkaller (https://github.com/google/syzkaller) #define _GNU_SOURCE #include <endian.h> #include <errno.h> #include <pthread.h> #include <setjmp.h> #include <signal.h> #include <stdint.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/syscall.h> #include <sys/types.h> #include <time.h> #include <unistd.h>
#include <linux/futex.h>
static __thread int skip_segv; static __thread jmp_buf segv_env;
static void segv_handler(int sig, siginfo_t* info, void* ctx) { 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)) { _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(...) \ { \ __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); \ }
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 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; for (i = 0; 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); }
#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))))
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); }
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_RELAXED)) return 1; now = current_time_ms(); if (now - start > timeout) return 0; } }
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 loop(void) { int i, call, thread; for (call = 0; call < 5; 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, 45); break; } } for (i = 0; i < 100 && __atomic_load_n(&running, __ATOMIC_RELAXED); i++) sleep_ms(1); }
uint64_t r[1] = {0x0};
void execute_call(int call) { long res; switch (call) { case 0: NONFAILING(*(uint32_t*)0x20000580 = 2); NONFAILING(*(uint32_t*)0x20000584 = 0x70); NONFAILING(*(uint8_t*)0x20000588 = 0x61); NONFAILING(*(uint8_t*)0x20000589 = 2); NONFAILING(*(uint8_t*)0x2000058a = 0); NONFAILING(*(uint8_t*)0x2000058b = 0); NONFAILING(*(uint32_t*)0x2000058c = 0); NONFAILING(*(uint64_t*)0x20000590 = 0); NONFAILING(*(uint64_t*)0x20000598 = 0); NONFAILING(*(uint64_t*)0x200005a0 = 0); NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 0, 1)); NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 1, 1)); NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 2, 1)); NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 3, 1)); NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 4, 1)); NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 5, 1)); NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 6, 1)); NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 7, 1)); NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 8, 1)); NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 9, 1)); NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 10, 1)); NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 11, 1)); NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 12, 1)); NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 13, 1)); NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 14, 1)); NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 15, 2)); NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 17, 1)); NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 18, 1)); NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 19, 1)); NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 20, 1)); NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 21, 1)); NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 22, 1)); NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 23, 1)); NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 24, 1)); NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 25, 1)); NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 26, 1)); NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 27, 1)); NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 28, 1)); NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 29, 35)); NONFAILING(*(uint32_t*)0x200005b0 = 0); NONFAILING(*(uint32_t*)0x200005b4 = 0); NONFAILING(*(uint64_t*)0x200005b8 = 0); NONFAILING(*(uint64_t*)0x200005c0 = 0); NONFAILING(*(uint64_t*)0x200005c8 = 0); NONFAILING(*(uint64_t*)0x200005d0 = 0); NONFAILING(*(uint32_t*)0x200005d8 = 0); NONFAILING(*(uint32_t*)0x200005dc = 0); NONFAILING(*(uint64_t*)0x200005e0 = 0); NONFAILING(*(uint32_t*)0x200005e8 = 0); NONFAILING(*(uint16_t*)0x200005ec = 0); NONFAILING(*(uint16_t*)0x200005ee = 0); syscall(__NR_perf_event_open, 0x20000580, 0, -1, -1, 0); break; case 1: syscall(__NR_clone, 0x20002100, 0, 0x9999999999999999, 0, -1); break; case 2: res = syscall(__NR_gettid); if (res != -1) r[0] = res; break; case 3: NONFAILING(*(uint64_t*)0x20000000 = 0); NONFAILING(*(uint32_t*)0x20000008 = 7); NONFAILING(*(uint32_t*)0x2000000c = 4); NONFAILING(*(uint32_t*)0x20000010 = r[0]); syscall(__NR_timer_create, 0, 0x20000000, 0x20000080); break; case 4: NONFAILING(*(uint64_t*)0x20000140 = 0); NONFAILING(*(uint64_t*)0x20000148 = 1); NONFAILING(*(uint64_t*)0x20000150 = 0); NONFAILING(*(uint64_t*)0x20000158 = 0x1c9c380); syscall(__NR_timer_settime, 0, 3, 0x20000140, 0); break; } } int main(void) { syscall(__NR_mmap, 0x20000000, 0x1000000, 3, 0x32, -1, 0); install_segv_handler(); loop(); return 0; } [unhandled content-type:application/octet-stream] | |