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x509v3/v3_purp.c: re-implement lock-free check for extensions cache validity.

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Reviewed-by: Paul Dale <paul.dale@oracle.com>
Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/6786)
This commit is contained in:
Andy Polyakov 2018-07-29 14:37:17 +02:00
parent 0da7358b07
commit f21b5b64cb
2 changed files with 12 additions and 0 deletions
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1
crypto/include/internal/x509_int.h
View file

@ -182,6 +182,7 @@ struct x509_st {
unsigned char sha1_hash[SHA_DIGEST_LENGTH];
X509_CERT_AUX *aux;
CRYPTO_RWLOCK *lock;
volatile int ex_cached;
} /* X509 */ ;
/*

11
crypto/x509v3/v3_purp.c
View file

@ -13,6 +13,7 @@
#include <openssl/x509v3.h>
#include <openssl/x509_vfy.h>
#include "internal/x509_int.h"
#include "internal/tsan_assist.h"
static void x509v3_cache_extensions(X509 *x);
@ -353,6 +354,10 @@ static void x509v3_cache_extensions(X509 *x)
X509_EXTENSION *ex;
int i;
/* fast lock-free check, see end of the function for details. */
if (tsan_load((TSAN_QUALIFIER int *)&x->ex_cached))
return;
CRYPTO_THREAD_write_lock(x->lock);
if (x->ex_flags & EXFLAG_SET) {
CRYPTO_THREAD_unlock(x->lock);
@ -494,6 +499,12 @@ static void x509v3_cache_extensions(X509 *x)
x509_init_sig_info(x);
x->ex_flags |= EXFLAG_SET;
CRYPTO_THREAD_unlock(x->lock);
/*
* It has to be placed after memory barrier, which is implied by unlock.
* Worst thing that can happen is that another thread proceeds to lock
* and checks x->ex_flags & EXFLAGS_SET. See beginning of the function.
*/
tsan_store((TSAN_QUALIFIER int *)&x->ex_cached, 1);
}
/*-