Re: Two valgrind warnings in OpenSSL - possible bug???

[Jeffrey Altman]

Paul Sheer wrote:

I valgrind'ed OpenSSL as follows:


without doing this you get infinite warnings - of course).

The results are as follows

==26139== Conditional jump or move depends on uninitialised value(s)
==26139==    at 0x81095FF: BN_mod_inverse (bn_gcd.c:215)
==26139==    by 0x810D29F: BN_MONT_CTX_set (bn_mont.c:406)
==26139==    by 0x8103E8F: BN_mod_exp_mont (bn_exp.c:417)
==26139==    by 0x81036E9: BN_mod_exp (bn_exp.c:223)
==26139==    by 0x81090FD: BN_BLINDING_create_param (bn_blind.c:352)
==26139==    by 0x80C9844: RSA_setup_blinding (rsa_lib.c:413)
==26139==
==26139== Conditional jump or move depends on uninitialised value(s)
==26139==    at 0x8128F5A: BN_div (bn_div.c:190)
==26139==    by 0x810D318: BN_MONT_CTX_set (bn_mont.c:417)
==26139==    by 0x8103E8F: BN_mod_exp_mont (bn_exp.c:417)
==26139==    by 0x81036E9: BN_mod_exp (bn_exp.c:223)
==26139==    by 0x81090FD: BN_BLINDING_create_param (bn_blind.c:352)
==26139==    by 0x80C9844: RSA_setup_blinding (rsa_lib.c:413)

...above repeated several times.

The code that gives the error is the BN_get_flags() macro
(see bn_div.c extract about line 190 below):

Could this be highlighting a bug in OpenSSL?????

Kind regards

-paul

I compiled OpenSSL (0.9.8g) with my own random number engine - in order to generate pseudo random numbers that are not based on unitialized values (if you run openssl

Reading the 0.9.8g code I see no uninitialized variables in these code paths. The BIGNUM pointers which are passed to the BN_get_flags() macro are parameters passed into the BN_mod_inverse() and BN_div() functions. In BN_MONT_CTX_set() those BIGNUM objects are initialized. I do not see why this warning is being triggered.

Jeffrey Altman

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