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    <p>If you really want to use LD_PRELOAD with malloc and found that the code in the accepted answer still segfaults, I have a solution that seems to work.</p> <p>The segfault was caused by dlsym calling calloc for 32 bytes, causing a recursion to the end of the stack. </p> <p>My solution was to create a super-simple static allocator that takes care of allocations before dlsym returns the malloc function pointer.</p> <pre><code>#define _GNU_SOURCE #include &lt;dlfcn.h&gt; #include &lt;stddef.h&gt; #include &lt;stdio.h&gt; #include &lt;stdlib.h&gt; char tmpbuff[1024]; unsigned long tmppos = 0; unsigned long tmpallocs = 0; void *memset(void*,int,size_t); void *memmove(void *to, const void *from, size_t size); /*========================================================= * interception points */ static void * (*myfn_calloc)(size_t nmemb, size_t size); static void * (*myfn_malloc)(size_t size); static void (*myfn_free)(void *ptr); static void * (*myfn_realloc)(void *ptr, size_t size); static void * (*myfn_memalign)(size_t blocksize, size_t bytes); static void init() { myfn_malloc = dlsym(RTLD_NEXT, "malloc"); myfn_free = dlsym(RTLD_NEXT, "free"); myfn_calloc = dlsym(RTLD_NEXT, "calloc"); myfn_realloc = dlsym(RTLD_NEXT, "realloc"); myfn_memalign = dlsym(RTLD_NEXT, "memalign"); if (!myfn_malloc || !myfn_free || !myfn_calloc || !myfn_realloc || !myfn_memalign) { fprintf(stderr, "Error in `dlsym`: %s\n", dlerror()); exit(1); } } void *malloc(size_t size) { static int initializing = 0; if (myfn_malloc == NULL) { if (!initializing) { initializing = 1; init(); initializing = 0; fprintf(stdout, "jcheck: allocated %lu bytes of temp memory in %lu chunks during initialization\n", tmppos, tmpallocs); } else { if (tmppos + size &lt; sizeof(tmpbuff)) { void *retptr = tmpbuff + tmppos; tmppos += size; ++tmpallocs; return retptr; } else { fprintf(stdout, "jcheck: too much memory requested during initialisation - increase tmpbuff size\n"); exit(1); } } } void *ptr = myfn_malloc(size); return ptr; } void free(void *ptr) { // something wrong if we call free before one of the allocators! // if (myfn_malloc == NULL) // init(); if (ptr &gt;= (void*) tmpbuff &amp;&amp; ptr &lt;= (void*)(tmpbuff + tmppos)) fprintf(stdout, "freeing temp memory\n"); else myfn_free(ptr); } void *realloc(void *ptr, size_t size) { if (myfn_malloc == NULL) { void *nptr = malloc(size); if (nptr &amp;&amp; ptr) { memmove(nptr, ptr, size); free(ptr); } return nptr; } void *nptr = myfn_realloc(ptr, size); return nptr; } void *calloc(size_t nmemb, size_t size) { if (myfn_malloc == NULL) { void *ptr = malloc(nmemb*size); if (ptr) memset(ptr, 0, nmemb*size); return ptr; } void *ptr = myfn_calloc(nmemb, size); return ptr; } void *memalign(size_t blocksize, size_t bytes) { void *ptr = myfn_memalign(blocksize, bytes); return ptr; } </code></pre> <p>Hope this helps someone.</p>
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    1. COit definitely did. see the first comment on https://github.com/jtolds/malloc_instrumentation/blob/9f8387bb270dd194e57aca38dc45039f4e54cc0a/malloc_instrument.c though i should point out that we since found a better way https://github.com/jtolds/malloc_instrumentation/commit/731c590ae88fcaa4d134ed0fc6b7b8f2836c520b
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