From: Junio C Hamano <gitster@pobox.com>
Date: Fri, 23 Oct 2026 18:49:37 GMT
Subject: Re: [PATCH v2] diff-delta: use safe integer arithmetic
Message-ID: <xmqq8q3o5k1q.fsf@gitster.g>
In-Reply-To: <fe3d651a-d1af-47a7-9b7b-a4ff242ca303@gmail.com>

Phillip Wood <phillip.wood123@gmail.com> writes:

>> +	memsize = st_add3(sizeof(*index),
>> +			st_mult(sizeof(*packed_hash), hsize + 1),
>
> What are the bounds of hsize? Can adding one to it overflow? The 
> alignment is off here as well, all the arguments to st_add3() should be 
> aligned.

Very good question, and I think hsize is capped at 1^26 in a code
early in this function, which makes this safe.  It needs to be
explained why it is safe in the log message, though.