path: root/crypto/mem_dbg.c

/*
 * Copyright 1995-2019 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the Apache License 2.0 (the "License").  You may not use
 * this file except in compliance with the License.  You can obtain a copy
 * in the file LICENSE in the source distribution or at
 * https://www.openssl.org/source/license.html
 */

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include "internal/cryptlib.h"
#include "internal/thread_once.h"
#include <openssl/crypto.h>
#include <openssl/buffer.h>
#include "internal/bio.h"
#include <openssl/lhash.h>

#ifndef OPENSSL_NO_CRYPTO_MDEBUG_BACKTRACE
# include <execinfo.h>
#endif

/*
 * The state changes to CRYPTO_MEM_CHECK_ON | CRYPTO_MEM_CHECK_ENABLE when
 * the application asks for it (usually after library initialisation for
 * which no book-keeping is desired). State CRYPTO_MEM_CHECK_ON exists only
 * temporarily when the library thinks that certain allocations should not be
 * checked (e.g. the data structures used for memory checking).  It is not
 * suitable as an initial state: the library will unexpectedly enable memory
 * checking when it executes one of those sections that want to disable
 * checking temporarily. State CRYPTO_MEM_CHECK_ENABLE without ..._ON makes
 * no sense whatsoever.
 */
#ifndef OPENSSL_NO_CRYPTO_MDEBUG
static int mh_mode = CRYPTO_MEM_CHECK_OFF;
#endif

#ifndef OPENSSL_NO_CRYPTO_MDEBUG
static unsigned long order = 0; /* number of memory requests */

static CRYPTO_ONCE memdbg_init = CRYPTO_ONCE_STATIC_INIT;
CRYPTO_RWLOCK *memdbg_lock;
static CRYPTO_RWLOCK *long_memdbg_lock;

/* memory-block description */
struct mem_st {
    void *addr;
    int num;
    const char *file;
    int line;
    CRYPTO_THREAD_ID threadid;
    unsigned long order;
    time_t time;
#ifndef OPENSSL_NO_CRYPTO_MDEBUG_BACKTRACE
    void *array[30];
    size_t array_siz;
#endif
};

/*
 * hash-table of memory requests (address as * key); access requires
 * long_memdbg_lock lock
 */
static LHASH_OF(MEM) *mh = NULL;

/* num_disable > 0 iff mh_mode == CRYPTO_MEM_CHECK_ON (w/o ..._ENABLE) */
static unsigned int num_disable = 0;

/*
 * Valid iff num_disable > 0.  long_memdbg_lock is locked exactly in this
 * case (by the thread named in disabling_thread).
 */
static CRYPTO_THREAD_ID disabling_threadid;

DEFINE_RUN_ONCE_STATIC(do_memdbg_init)
{
    memdbg_lock = CRYPTO_THREAD_lock_new();
    long_memdbg_lock = CRYPTO_THREAD_lock_new();
    if (memdbg_lock == NULL || long_memdbg_lock == NULL) {
        CRYPTO_THREAD_lock_free(memdbg_lock);
        memdbg_lock = NULL;
        CRYPTO_THREAD_lock_free(long_memdbg_lock);
        long_memdbg_lock = NULL;
        return 0;
    }
    return 1;
}

#endif

int CRYPTO_mem_ctrl(int mode)
{
#ifdef OPENSSL_NO_CRYPTO_MDEBUG
    return mode - mode;
#else
    int ret = mh_mode;

    if (!RUN_ONCE(&memdbg_init, do_memdbg_init))
        return -1;

    CRYPTO_THREAD_write_lock(memdbg_lock);
    switch (mode) {
    default:
        break;

    case CRYPTO_MEM_CHECK_ON:
        mh_mode = CRYPTO_MEM_CHECK_ON | CRYPTO_MEM_CHECK_ENABLE;
        num_disable = 0;
        break;

    case CRYPTO_MEM_CHECK_OFF:
        mh_mode = 0;
        num_disable = 0;
        break;

    /* switch off temporarily (for library-internal use): */
    case CRYPTO_MEM_CHECK_DISABLE:
        if (mh_mode & CRYPTO_MEM_CHECK_ON) {
            CRYPTO_THREAD_ID cur = CRYPTO_THREAD_get_current_id();
            /* see if we don't have long_memdbg_lock already */
            if (!num_disable
                || !CRYPTO_THREAD_compare_id(disabling_threadid, cur)) {
                /*
                 * Long-time lock long_memdbg_lock must not be claimed
                 * while we're holding memdbg_lock, or we'll deadlock
                 * if somebody else holds long_memdbg_lock (and cannot
                 * release it because we block entry to this function). Give
                 * them a chance, first, and then claim the locks in
                 * appropriate order (long-time lock first).
                 */
                CRYPTO_THREAD_unlock(memdbg_lock);
                /*
                 * Note that after we have waited for long_memdbg_lock and
                 * memdbg_lock, we'll still be in the right "case" and
                 * "if" branch because MemCheck_start and MemCheck_stop may
                 * never be used while there are multiple OpenSSL threads.
                 */
                CRYPTO_THREAD_write_lock(long_memdbg_lock);
                CRYPTO_THREAD_write_lock(memdbg_lock);
                mh_mode &= ~CRYPTO_MEM_CHECK_ENABLE;
                disabling_threadid = cur;
            }
            num_disable++;
        }
        break;

    case CRYPTO_MEM_CHECK_ENABLE:
        if (mh_mode & CRYPTO_MEM_CHECK_ON) {
            if (num_disable) {  /* always true, or something is going wrong */
                num_disable--;
                if (num_disable == 0) {
                    mh_mode |= CRYPTO_MEM_CHECK_ENABLE;
                    CRYPTO_THREAD_unlock(long_memdbg_lock);
                }
            }
        }
        break;
    }
    CRYPTO_THREAD_unlock(memdbg_lock);
    return ret;
#endif
}

#ifndef OPENSSL_NO_CRYPTO_MDEBUG

static int mem_check_on(void)
{
    int ret = 0;
    CRYPTO_THREAD_ID cur;

    if (mh_mode & CRYPTO_MEM_CHECK_ON) {
        if (!RUN_ONCE(&memdbg_init, do_memdbg_init))
            return 0;

        cur = CRYPTO_THREAD_get_current_id();
        CRYPTO_THREAD_read_lock(memdbg_lock);

        ret = (mh_mode & CRYPTO_MEM_CHECK_ENABLE)
            || !CRYPTO_THREAD_compare_id(disabling_threadid, cur);

        CRYPTO_THREAD_unlock(memdbg_lock);
    }
    return ret;
}

static int mem_cmp(const MEM *a, const MEM *b)
{
#ifdef _WIN64
    const char *ap = (const char *)a->addr, *bp = (const char *)b->addr;
    if (ap == bp)
        return 0;
    else if (ap > bp)
        return 1;
    else
        return -1;
#else
    return (const char *)a->addr - (const char *)b->addr;
#endif
}

static unsigned long mem_hash(const MEM *a)
{
    size_t ret;

    ret = (size_t)a->addr;

    ret = ret * 17851 + (ret >> 14) * 7 + (ret >> 4) * 251;
    return ret;
}

#if !OPENSSL_API_3
int CRYPTO_mem_debug_push(const char *info, const char *file, int line)
{
    return 0;
}

int CRYPTO_mem_debug_pop(void)
{
    return 0;
}
#endif

static unsigned long break_order_num = 0;

void CRYPTO_mem_debug_malloc(void *addr, size_t num, int before_p,
                             const char *file, int line)
{
    MEM *m, *mm;

    switch (before_p & 127) {
    case 0:
        break;
    case 1:
        if (addr == NULL)
            break;

        if (mem_check_on()) {
            CRYPTO_mem_ctrl(CRYPTO_MEM_CHECK_DISABLE);

            if (!RUN_ONCE(&memdbg_init, do_memdbg_init)
                || (m = OPENSSL_malloc(sizeof(*m))) == NULL) {
                OPENSSL_free(addr);
                CRYPTO_mem_ctrl(CRYPTO_MEM_CHECK_ENABLE);
                return;
            }
            if (mh == NULL) {
                if ((mh = lh_MEM_new(mem_hash, mem_cmp)) == NULL) {
                    OPENSSL_free(addr);
                    OPENSSL_free(m);
                    addr = NULL;
                    goto err;
                }
            }

            m->addr = addr;
            m->file = file;
            m->line = line;
            m->num = num;
            m->threadid = CRYPTO_THREAD_get_current_id();

            if (order == break_order_num) {
                /* BREAK HERE */
                m->order = order;
            }
            m->order = order++;
# ifndef OPENSSL_NO_CRYPTO_MDEBUG_BACKTRACE
            m->array_siz = backtrace(m->array, OSSL_NELEM(m->array));
# endif
            m->time = time(NULL);

            if ((mm = lh_MEM_insert(mh, m)) != NULL)
                OPENSSL_free(mm);
 err:
            CRYPTO_mem_ctrl(CRYPTO_MEM_CHECK_ENABLE);
        }
        break;
    }
    return;
}