There is a patch that illustrates how I've been going about the crypto/bn/ "audit" that can be browsed/downloaded at;
http://www.openssl.org/~geoff/bn_debug.diff The comment in the bn.h header changes explains what the basic idea is and of course the macro definitions there define what's going on. However, I wanted to add a few extra notes in no particular order, in case someone else wants to take a look. BTW: this is all relative to the head of CVS (so tonight's snapshot at ftp://ftp.openssl.org/snapshot/ should also be fine). - I've had to turn off the "BN_DEBUG_RAND" stuff in the macros because this already exposes some non-trivial problems in bn_div.c and (I think) BN_rshift(). So much of this code is only used in certain configurations, so use of assembly (or "long long") may not trigger it, but the "debug-geoff" target certainly does. ;-) - I've mostly been using "make test" (and specifically, ./test/bntest) - As/when the code can handle BN_DEBUG_RAND turned on, the same "noise" trick should be used in bn_correct_top() so that there are more code paths trying to trigger bugs. - The macros are all kept together in bn.h, which includes bn_check_top() which was taken out of bn_lcl.h, but eventually these should all go back in bn_lcl.h. - There are other things to fix/change - including making the existing macros and functions stop tolerating two representations of zero, this may highlight more crappy code elsewhere. But one thing at a time ... - I think I've got most of the function exit paths covered with bn_check_top() macros, though there may be those I've missed. - I've not even begun to look at API macros that should have this checking included, no doubt that could turn up some more bugs too. - The bugs that've been found (and fixed) so far are already committed, but I suspect there's more coming out ... if any of us can bare to dig into the code, that is. - It would be easiest to put this stuff in to CVS, as it will make collaboration easier and may give some people less reason to ignore it. Any objections? Any feedback would be most welcome. Cheers, Geoff -- Geoff Thorpe [EMAIL PROTECTED] http://www.openssl.org/ ______________________________________________________________________ OpenSSL Project http://www.openssl.org Development Mailing List [EMAIL PROTECTED] Automated List Manager [EMAIL PROTECTED]
