Date: Mon, 18 Oct 2021 07:40:25 GMT From: Peter Holm <pho@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 26c1772071f7 - main - stress2: Added a syzkaller reproducer Message-ID: <202110180740.19I7ePlP044733@gitrepo.freebsd.org>
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The branch main has been updated by pho: URL: https://cgit.FreeBSD.org/src/commit/?id=26c1772071f70b6266fe95a2f235c7a50813732b commit 26c1772071f70b6266fe95a2f235c7a50813732b Author: Peter Holm <pho@FreeBSD.org> AuthorDate: 2021-10-18 07:39:55 +0000 Commit: Peter Holm <pho@FreeBSD.org> CommitDate: 2021-10-18 07:39:55 +0000 stress2: Added a syzkaller reproducer --- syzkaller45.sh | 289 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 289 insertions(+) diff --git a/syzkaller45.sh b/syzkaller45.sh new file mode 100755 index 000000000000..6c38b96ab12b --- /dev/null +++ b/syzkaller45.sh @@ -0,0 +1,289 @@ +#!/bin/sh + +# panic: Assertion (cnp->cn_flags & (LOCKPARENT | WANTPARENT)) == 0 failed at ../../../kern/vfs_cache.c:4790 +# cpuid = 5 +# time = 1634453452 +# KDB: stack backtrace: +# db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 0xfffffe0146912830 +# vpanic() at vpanic+0x187/frame 0xfffffe0146912890 +# panic() at panic+0x43/frame 0xfffffe01469128f0 +# cache_fplookup_emptypath() at cache_fplookup_emptypath+0x1b2/frame 0xfffffe0146912930 +# cache_fplookup_noentry() at cache_fplookup_noentry+0xbc/frame 0xfffffe01469129a0 +# cache_fplookup() at cache_fplookup+0x605/frame 0xfffffe0146912a90 +# namei() at namei+0x203/frame 0xfffffe0146912b50 +# vn_open_cred() at vn_open_cred+0x12c/frame 0xfffffe0146912cb0 +# kern_openat() at kern_openat+0x285/frame 0xfffffe0146912e00 +# amd64_syscall() at amd64_syscall+0x147/frame 0xfffffe0146912f30 +# fast_syscall_common() at fast_syscall_common+0xf8/frame 0xfffffe0146912f30 +# --- syscall (0, FreeBSD ELF64, nosys), rip = 0x8003aeafa, rsp = 0x7fffdfffdf28, rbp = 0x7fffdfffdf70 --- +# KDB: enter: panic +# [ thread pid 2864 tid 100315 ] +# Stopped at kdb_enter+0x37: movq $0,0x126f74e(%rip) +# db> x/s version +# version: FreeBSD 14.0-CURRENT #0 main-n250087-a7d137fcbcac: Sun Oct 17 08:46:08 CEST 2021 +# pho@mercat1.netperf.freebsd.org:/usr/src/sys/amd64/compile/PHO\012 +# db> + +# Fixed by 1045352f1503 + +[ `uname -p` != "amd64" ] && exit 0 +[ `id -u ` -ne 0 ] && echo "Must be root!" && exit 1 + +. ../default.cfg +cat > /tmp/syzkaller45.c <<EOF +// https://syzkaller.appspot.com/bug?id=283995ae4346041c1757f62f3322a3545d0a62a4 +// autogenerated by syzkaller (https://github.com/google/syzkaller) +// Reported-by: syzbot+bd48ee0843206a09e6b8@syzkaller.appspotmail.com + +#define _GNU_SOURCE + +#include <errno.h> +#include <pthread.h> +#include <pwd.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/endian.h> +#include <sys/syscall.h> +#include <time.h> +#include <unistd.h> + +static __thread int skip_segv; +static __thread jmp_buf segv_env; + +static void segv_handler(int sig, siginfo_t* info, void* ctx __unused) +{ + 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 (sig == SIGBUS) + valid = 1; + 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_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 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 { + pthread_mutex_t mu; + pthread_cond_t cv; + int state; +} event_t; + +static void event_init(event_t* ev) +{ + if (pthread_mutex_init(&ev->mu, 0)) + exit(1); + if (pthread_cond_init(&ev->cv, 0)) + exit(1); + ev->state = 0; +} + +static void event_reset(event_t* ev) +{ + ev->state = 0; +} + +static void event_set(event_t* ev) +{ + pthread_mutex_lock(&ev->mu); + if (ev->state) + exit(1); + ev->state = 1; + pthread_mutex_unlock(&ev->mu); + pthread_cond_broadcast(&ev->cv); +} + +static void event_wait(event_t* ev) +{ + pthread_mutex_lock(&ev->mu); + while (!ev->state) + pthread_cond_wait(&ev->cv, &ev->mu); + pthread_mutex_unlock(&ev->mu); +} + +static int event_isset(event_t* ev) +{ + pthread_mutex_lock(&ev->mu); + int res = ev->state; + pthread_mutex_unlock(&ev->mu); + return res; +} + +static int event_timedwait(event_t* ev, uint64_t timeout) +{ + uint64_t start = current_time_ms(); + uint64_t now = start; + pthread_mutex_lock(&ev->mu); + for (;;) { + if (ev->state) + break; + uint64_t remain = timeout - (now - start); + struct timespec ts; + ts.tv_sec = remain / 1000; + ts.tv_nsec = (remain % 1000) * 1000 * 1000; + pthread_cond_timedwait(&ev->cv, &ev->mu, &ts); + now = current_time_ms(); + if (now - start > timeout) + break; + } + int res = ev->state; + pthread_mutex_unlock(&ev->mu); + return res; +} + +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; + int collide = 0; +again: + 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); + if (collide && (call % 2) == 0) + break; + event_timedwait(&th->done, 50); + break; + } + } + for (i = 0; i < 100 && __atomic_load_n(&running, __ATOMIC_RELAXED); i++) + sleep_ms(1); + if (!collide) { + collide = 1; + goto again; + } +} + +uint64_t r[1] = {0xffffffffffffffff}; + +void execute_call(int call) +{ + intptr_t res = 0; + switch (call) { + case 0: + NONFAILING(memcpy((void*)0x20000480, "./file0\000", 8)); + res = syscall(SYS_open, 0x20000480ul, 0x80400000000206ul, 0ul); + if (res != -1) + r[0] = res; + break; + case 1: + syscall(SYS_mmap, 0x20000000ul, 0x200000ul, 1ul, 0x12ul, r[0], 0ul); + break; + case 2: + syscall(SYS_ftruncate, r[0], 5ul); + break; + } +} +int main(void) +{ + syscall(SYS_mmap, 0x20000000ul, 0x1000000ul, 7ul, 0x1012ul, -1, 0ul); + install_segv_handler(); + loop(); + return 0; +} +EOF +mycc -o /tmp/syzkaller45 -Wall -Wextra -O0 /tmp/syzkaller45.c -lpthread || exit 1 + +(cd /tmp; ./syzkaller45) + +rm -rf /tmp/syzkaller45 /tmp/syzkaller45.c /tmp/syzkaller.* /tmp/file0 +exit 0
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