[Bug 20567] Uninitialised memory reference in RSAENH_CPImportKey

[wine-bugs at winehq.org]

http://bugs.winehq.org/show_bug.cgi?id=20567





--- Comment #5 from Juan Lang <juan_lang at yahoo.com>  2009-11-04 13:06:33 ---
Created an attachment (id=24551)
 --> (http://bugs.winehq.org/attachment.cgi?id=24551)
Patch

Does this patch help?

I believe I see the source of the problem:  a key of a given length doesn't
necessarily need that many bits to store.  Consider the number 2:  it's valid
as a 32-bit number, but it doesn't need more than 2 bits to store.  When
exporting a key, the function mp_to_unsigned_bin writes one byte of a number at
a time to memory, and divides the number by 8 to discard the byte it just
wrote.  It stops when the result of the division is zero:  there are no
significant bytes remaining.

This patch makes sure to set to 0 the insignificant bytes.  I don't know why
neglecting to do this didn't cause issues before, except if the memory was
implicitly zeroed (or unless my understanding is incorrect, which is perhaps
more likely.)

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