775337 - <Hash>_HashBuf should zero its local context variable before returning

Status: RESOLVED FIXED

(NSS :: Libraries, defect, P2)

Description

[Wan-Teh Chang]

Attachment: Proposed patch

This was originally suggested by David Cooper in bug 590515 comment 8.

The <Hash>_HashBuf functions, such as SHA256_HashBuf, should zero their
local context variables before returning because we often hash secret
data.  This matches the behavior of <Hash>_DestroyContext.

I also discovered that most <Hash>_DestroyContext functions zero their
context arguments only if the 'freeit' argument is true.  I also changed
them to always zero their context arguments, matching the behavior of
SHA1_DestroyContext.

Comment 1

[Robert Relyea]

Comment on attachment 643635 [details] [diff] [review]
Proposed patch

r+ rrelyea.

I suspect this was a nelson optimization to get a few extra percent.

bob

Comment 2

[Wan-Teh Chang]

Patch checked in on the NSS trunk (NSS 3.14).

Checking in md5.c;
/cvsroot/mozilla/security/nss/lib/freebl/md5.c,v  <--  md5.c
new revision: 1.16; previous revision: 1.15
done
Checking in sha512.c;
/cvsroot/mozilla/security/nss/lib/freebl/sha512.c,v  <--  sha512.c
new revision: 1.21; previous revision: 1.20
done
Checking in sha_fast.c;
/cvsroot/mozilla/security/nss/lib/freebl/sha_fast.c,v  <--  sha_fast.c
new revision: 1.15; previous revision: 1.14
done