From 8285069f89c9942f65ce760a8f0a5a12254bfeeb Mon Sep 17 00:00:00 2001 From: Dmitry Vyukov Date: Sat, 18 May 2019 17:54:03 +0200 Subject: executor: implement support for leak checking Leak checking support was half done and did not really work. This is heavy-lifting to make it work. 1. Move leak/fault setup into executor. pkg/host was a wrong place for them because we need then in C repros too. The pkg/host periodic callback functionality did not work too, we need it in executor so that we can reuse it in C repros too. Remove setup/callback functions in pkg/host entirely. 2. Do leak setup/checking in C repros. The way leak checking is invoked is slightly different from fuzzer, but much better then no support at all. At least the checking code is shared. 3. Add Leak option to pkg/csource and -leak flag to syz-prog2c. 4. Don't enalbe leak checking in fuzzer while we are triaging initial corpus. It's toooo slow. 5. Fix pkg/repro to do something more sane for leak bugs. Few other minor fixes here and there. --- executor/common_linux.h | 182 ++++++++++++++++++++++++++++++++++++++++-------- 1 file changed, 152 insertions(+), 30 deletions(-) (limited to 'executor/common_linux.h') diff --git a/executor/common_linux.h b/executor/common_linux.h index 2d1460ee6..4c33acdea 100644 --- a/executor/common_linux.h +++ b/executor/common_linux.h @@ -71,7 +71,8 @@ static int event_timedwait(event_t* ev, uint64 timeout) #endif #if SYZ_EXECUTOR || SYZ_REPEAT || SYZ_TUN_ENABLE || SYZ_FAULT_INJECTION || SYZ_SANDBOX_NONE || \ - SYZ_SANDBOX_SETUID || SYZ_SANDBOX_NAMESPACE || SYZ_SANDBOX_ANDROID_UNTRUSTED_APP + SYZ_SANDBOX_SETUID || SYZ_SANDBOX_NAMESPACE || SYZ_SANDBOX_ANDROID_UNTRUSTED_APP || \ + SYZ_FAULT_INJECTION || SYZ_ENABLE_LEAK || SYZ_ENABLE_BINFMT_MISC #include #include #include @@ -1868,26 +1869,6 @@ void initialize_cgroups() #endif #endif -#if SYZ_EXECUTOR || (SYZ_ENABLE_BINFMT_MISC && (SYZ_SANDBOX_NONE || SYZ_SANDBOX_SETUID || SYZ_SANDBOX_NAMESPACE || SYZ_SANDBOX_ANDROID_UNTRUSTED_APP)) -#include -#include -#include -#include - -static void setup_binfmt_misc() -{ -#if SYZ_EXECUTOR - if (!flag_enable_binfmt_misc) - return; -#endif - if (mount(0, "/proc/sys/fs/binfmt_misc", "binfmt_misc", 0, 0)) { - debug("mount(binfmt_misc) failed: %d\n", errno); - } - write_file("/proc/sys/fs/binfmt_misc/register", ":syz0:M:0:\x01::./file0:"); - write_file("/proc/sys/fs/binfmt_misc/register", ":syz1:M:1:\x02::./file0:POC"); -} -#endif - #if SYZ_EXECUTOR || SYZ_SANDBOX_NONE || SYZ_SANDBOX_SETUID || SYZ_SANDBOX_NAMESPACE || SYZ_SANDBOX_ANDROID_UNTRUSTED_APP #include #include @@ -1900,9 +1881,6 @@ static void setup_common() #if SYZ_EXECUTOR || SYZ_ENABLE_CGROUPS setup_cgroups(); #endif -#if SYZ_EXECUTOR || SYZ_ENABLE_BINFMT_MISC - setup_binfmt_misc(); -#endif } #include @@ -2475,10 +2453,6 @@ retry: static int inject_fault(int nth) { -#if SYZ_EXECUTOR - if (!flag_enable_fault_injection) - return 0; -#endif int fd; fd = open("/proc/thread-self/fail-nth", O_RDWR); // We treat errors here as temporal/non-critical because we see @@ -2497,8 +2471,6 @@ static int inject_fault(int nth) #if SYZ_EXECUTOR static int fault_injected(int fail_fd) { - if (!flag_enable_fault_injection) - return 0; char buf[16]; int n = read(fail_fd, buf, sizeof(buf) - 1); if (n <= 0) @@ -2646,3 +2618,153 @@ static void close_fds() close(fd); } #endif + +#if SYZ_EXECUTOR || SYZ_FAULT_INJECTION +#include + +static void setup_fault() +{ + static struct { + const char* file; + const char* val; + bool fatal; + } files[] = { + {"/sys/kernel/debug/failslab/ignore-gfp-wait", "N", true}, + // These are enabled by separate configs (e.g. CONFIG_FAIL_FUTEX) + // and we did not check all of them in host.checkFaultInjection, so we ignore errors. + {"/sys/kernel/debug/fail_futex/ignore-private", "N", false}, + {"/sys/kernel/debug/fail_page_alloc/ignore-gfp-highmem", "N", false}, + {"/sys/kernel/debug/fail_page_alloc/ignore-gfp-wait", "N", false}, + {"/sys/kernel/debug/fail_page_alloc/min-order", "0", false}, + }; + unsigned i; + for (i = 0; i < sizeof(files) / sizeof(files[0]); i++) { + if (!write_file(files[i].file, files[i].val)) { + debug("failed to write %s: %d\n", files[i].file, errno); + if (files[i].fatal) + fail("failed to write %s", files[i].file); + } + } +} +#endif + +#if SYZ_EXECUTOR || SYZ_ENABLE_LEAK +#include +#include +#include +#include +#include + +#define KMEMLEAK_FILE "/sys/kernel/debug/kmemleak" + +static void setup_leak() +{ + // Flush boot leaks. + if (!write_file(KMEMLEAK_FILE, "scan")) + fail("failed to write %s", KMEMLEAK_FILE); + sleep(5); // account for MSECS_MIN_AGE + if (!write_file(KMEMLEAK_FILE, "scan")) + fail("failed to write %s", KMEMLEAK_FILE); + if (!write_file(KMEMLEAK_FILE, "clear")) + fail("failed to write %s", KMEMLEAK_FILE); +} + +#define SYZ_HAVE_LEAK_CHECK 1 +#if SYZ_EXECUTOR +static void check_leaks(char** frames, int nframes) +#else +static void check_leaks(void) +#endif +{ + int fd = open(KMEMLEAK_FILE, O_RDWR); + if (fd == -1) + fail("failed to open(\"%s\")", KMEMLEAK_FILE); + // KMEMLEAK has false positives. To mitigate most of them, it checksums + // potentially leaked objects, and reports them only on the next scan + // iff the checksum does not change. Because of that we do the following + // intricate dance: + // Scan, sleep, scan again. At this point we can get some leaks. + // If there are leaks, we sleep and scan again, this can remove + // false leaks. Then, read kmemleak again. If we get leaks now, then + // hopefully these are true positives during the previous testing cycle. + uint64 start = current_time_ms(); + if (write(fd, "scan", 4) != 4) + fail("failed to write(%s, \"scan\")", KMEMLEAK_FILE); + sleep(1); + // Account for MSECS_MIN_AGE + // (1 second less because scanning will take at least a second). + while (current_time_ms() - start < 4 * 1000) + sleep(1); + if (write(fd, "scan", 4) != 4) + fail("failed to write(%s, \"scan\")", KMEMLEAK_FILE); + static char buf[128 << 10]; + ssize_t n = read(fd, buf, sizeof(buf) - 1); + if (n < 0) + fail("failed to read(%s)", KMEMLEAK_FILE); +#if SYZ_EXECUTOR + int nleaks = 0; +#endif + if (n != 0) { + sleep(1); + if (write(fd, "scan", 4) != 4) + fail("failed to write(%s, \"scan\")", KMEMLEAK_FILE); + if (lseek(fd, 0, SEEK_SET) < 0) + fail("failed to lseek(%s)", KMEMLEAK_FILE); + n = read(fd, buf, sizeof(buf) - 1); + if (n < 0) + fail("failed to read(%s)", KMEMLEAK_FILE); + buf[n] = 0; + char* pos = buf; + char* end = buf + n; + while (pos < end) { + char* next = strstr(pos + 1, "unreferenced object"); + if (!next) + next = end; + char prev = *next; + *next = 0; +#if SYZ_EXECUTOR + int f; + for (f = 0; f < nframes; f++) { + if (strstr(pos, frames[f])) + break; + } + if (f != nframes) { + *next = prev; + pos = next; + continue; + } +#endif + // BUG in output should be recognized by manager. + fprintf(stderr, "BUG: memory leak\n%s\n", pos); + *next = prev; + pos = next; +#if SYZ_EXECUTOR + nleaks++; +#endif + } + } + if (write(fd, "clear", 5) != 5) + fail("failed to write(%s, \"clear\")", KMEMLEAK_FILE); + close(fd); +#if SYZ_EXECUTOR + if (nleaks) + doexit(1); +#endif +} +#endif + +#if SYZ_EXECUTOR || SYZ_ENABLE_BINFMT_MISC +#include +#include +#include +#include + +static void setup_binfmt_misc() +{ + if (mount(0, "/proc/sys/fs/binfmt_misc", "binfmt_misc", 0, 0)) { + debug("mount(binfmt_misc) failed: %d\n", errno); + } + write_file("/proc/sys/fs/binfmt_misc/register", ":syz0:M:0:\x01::./file0:"); + write_file("/proc/sys/fs/binfmt_misc/register", ":syz1:M:1:\x02::./file0:POC"); +} +#endif -- cgit mrf-deployment