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To prevent the information from being written to a core dump, the size of core dumps that the program will generate should be set to 0 using setrlimit().:
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#include <sys/resource.h>
/* ... */
struct rlimit limit;
limit.rlim_cur = 0;
limit.rlim_max = 0;
if (setrlimit(RLIMIT_CORE, &limit) != 0) {
/* Handle error */
}
char *secret;
secret = (char *)malloc(size+1);
if (!secret) {
/* Handle error */
}
/* Perform operations using secret... */
free(secret);
secret = NULL;
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This compliant solution not only disables the creation of core files but also ensures that the buffer is not swapped to hard disk.:
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#include <sys/resource.h>
/* ... */
struct rlimit limit;
limit.rlim_cur = 0;
limit.rlim_max = 0;
if (setrlimit(RLIMIT_CORE, &limit) != 0) {
/* Handle error */
}
long pagesize = sysconf(_SC_PAGESIZE);
if (pagesize == -1) {
/* Handle error */
}
char *secret_buf;
char *secret;
secret_buf = (char *)malloc(size+1+pagesize);
if (!secret_buf) {
/* Handle error */
}
/* mlock() may require that the address be a multiple of PAGESIZE */
secret = (char *)((((intptr_t)secret_buf + pagesize - 1) / pagesize) * pagesize);
if (mlock(secret, size+1) != 0) {
/* Handle error */
}
/* Perform operations using secret... */
if (munlock(secret, size+1) != 0) {
/* Handle error */
}
secret = NULL;
free(secret_buf);
secret_buf = NULL;
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