RFR: JDK-8321599 Data loss in AVX3 Base64 decoding [v5]

[Sandhya Viswanathan]

On Wed, 20 Dec 2023 00:06:39 GMT, Scott Gibbons <sgibbons at openjdk.org> wrote:

>> Fix for looking for padding characters within the encoded string.  Was not adding start offset to length, so was looking at potentially freed or uninitialized memory.
>> 
>> Tested teir1 and with testcase supplied with JBS issue.
>> 
>> The problem will only occur when all of the following are true:
>> 1. The source offset of the string to be decoded is != 0.
>> 2. The characters at the beginning of the string (minus the offset) plus the string length mod 64 are either "=" or "==".
>> 3. The string is >= 32 characters.
>> 4. The string is not MIME encoded.
>> 
>> If any of these conditions are not met, the decode works as expected. This was due to omitting the source offset of the string when checking for padding characters.
>
> Scott Gibbons has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - Updated copyright year
>  - Updated copyright year

Marked as reviewed by sviswanathan (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/17039#pullrequestreview-1789883368