Fix BN_DEBUG: ossl_assert() → assert()

ossl_assert() has been modified so much that it no longer fits the
purpose of bn_check_top() when BN_DEBUG is defined in a debug build,
which is to abort and tell where the BIGNUM is inconsistent.  This
is by design.

This has remained undiscovered because no one has tried BN_DEBUG
for quite a while.

Assertions in bn_check_top() are also rearranged to better show what
the actual problem is.

Reviewed-by: Dmitry Belyavskiy <beldmit@gmail.com>
Reviewed-by: Tom Cosgrove <tom.cosgrove@arm.com>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/28801)

diff --git a/crypto/bn/bn_local.h b/crypto/bn/bn_local.h
index 10b93729a7346c95b94f24ab78466a932bc34833..bb889d6116f3f589a897348551c089453c229f50 100644 (file)
--- a/crypto/bn/bn_local.h
+++ b/crypto/bn/bn_local.h
@@ -158,6 +158,10 @@
  */
 
 # ifdef BN_DEBUG
+
+/* ossl_assert() isn't fit for BN_DEBUG purposes, use assert() instead */
+#  include <assert.h>
+
 /*
  * The new BN_FLG_FIXED_TOP flag marks vectors that were not treated with
  * bn_correct_top, in other words such vectors are permitted to have zeros
@@ -192,9 +196,11 @@
                 const BIGNUM *_bnum2 = (a); \
                 if (_bnum2 != NULL) { \
                         int _top = _bnum2->top; \
-                        (void)ossl_assert((_top == 0 && !_bnum2->neg) || \
-                                  (_top && ((_bnum2->flags & BN_FLG_FIXED_TOP) \
-                                            || _bnum2->d[_top - 1] != 0))); \
+                        if (_top == 0) { \
+                                assert(!_bnum2->neg); \
+                        } else if ((_bnum2->flags & BN_FLG_FIXED_TOP) == 0) { \
+                                assert(_bnum2->d[_top - 1] != 0); \
+                        } \
                         bn_pollute(_bnum2); \
                 } \
         } while(0)