commit 8cd091a8d3133e9e5363bc4a673011178e54ab5d Author: Nick Mathewson <nickm@torproject.org> Date: Wed Sep 5 16:34:01 2018 -0400 Add a last-ditch memwipe() implementation for nss+old glibc On new glibc versions, there's an explicit_bzero(). With openssl, there's openssl_memwipe(). When no other approach works, use memwipe() and a memory barrier. --- src/lib/crypt_ops/crypto_util.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/src/lib/crypt_ops/crypto_util.c b/src/lib/crypt_ops/crypto_util.c index 7af80291e..42024907e 100644 --- a/src/lib/crypt_ops/crypto_util.c +++ b/src/lib/crypt_ops/crypto_util.c @@ -80,7 +80,7 @@ memwipe(void *mem, uint8_t byte, size_t sz) #elif defined(HAVE_MEMSET_S) /* This is in the C99 standard. */ memset_s(mem, sz, 0, sz); -#else +#elif defined(ENABLE_OPENSSL) /* This is a slow and ugly function from OpenSSL that fills 'mem' with junk * based on the pointer value, then uses that junk to update a global * variable. It's an elaborate ruse to trick the compiler into not @@ -93,6 +93,9 @@ memwipe(void *mem, uint8_t byte, size_t sz) **/ OPENSSL_cleanse(mem, sz); +#else + memset(mem, 0, sz); + asm volatile ("" ::: "memory"); #endif /* defined(SecureZeroMemory) || defined(HAVE_SECUREZEROMEMORY) || ... */ /* Just in case some caller of memwipe() is relying on getting a buffer @@ -105,4 +108,5 @@ memwipe(void *mem, uint8_t byte, size_t sz) * if somebody accidentally calls memwipe() instead of memset(). **/ memset(mem, byte, sz); + }