[Webkit-unassigned] [Bug 210540] Fix an integer overflow in WebCrypto AES-CTR Mac implementation, which may detect a false loop

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=210540

--- Comment #5 from Jiewen Tan <jiewen_tan at apple.com> ---
Comment on attachment 396514
  --> https://bugs.webkit.org/attachment.cgi?id=396514
patch

View in context: https://bugs.webkit.org/attachment.cgi?id=396514&action=review

>>> Source/WebCore/crypto/mac/CryptoAlgorithmAES_CTRMac.cpp:48
>>> +    if (counterLength < sizeof(size_t) * 8 && numberOfBlocks > ((size_t)1 << counterLength))
>> 
>> ((size_t)1 => 1ull
> 
> I used ((size_t) 1) rather than 1ull, because I thought using size_t type makes more sense than "unsigned long long".
> - "counterLength < sizeof(size_t) * 8" checks whether size_t has enough size to store (1 << counterLength)
> - In 32-bit environment, 1ull, which is 64-bit or larger, is a bit overkill, because counterLength < 31 in 32-bit environment.
> 
> How do you think about it?
> Of course, 1ull should work fine both on 32-bit and 64-bit environment, so I'm fine to change it to 1ull.

I was not aware we are still supporting 32 bit machines. Doing a C style cast is not appropriate in WebKit, please change it to static_cast<size_t>(1).

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