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Re: Optimized memcmp for x86 [message #14363 is a reply to message #14360]

Sat, 23 February 2008 22:18

cbpporter
Messages: 1428
Registered: September 2007

Ultimate Contributor

Quote:

Than again if such OS allocators allow to allocate only for example 4kB chunks and not 13 bytes, I think it will never raise exception or crash and you may safely read beyond end of buffer.

That is true, but it will not allocate those 4KB for every 13 bytes you want, only if the previoslly allocated 4KB chunk is full. Your requested pointer may be on the end of that allocated zone, and here you could have big problems.

Anyway, this is a memcmp operation, so even if you don't crash, just getting gibberish data could compromise the functionality.

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[Message index]

		Optimized memcmp for x86 By: mirek on Fri, 22 February 2008 11:07
		Re: Optimized memcmp for x86 By: mr_ped on Fri, 22 February 2008 19:08
		Re: Optimized memcmp for x86 By: mirek on Sat, 23 February 2008 16:15
		Re: Optimized memcmp for x86 By: mr_ped on Fri, 22 February 2008 19:52
		Re: Optimized memcmp for x86 By: mr_ped on Sat, 23 February 2008 18:56
		Re: Optimized memcmp for x86 By: cbpporter on Sat, 23 February 2008 22:18
		Re: Optimized memcmp for x86 By: mr_ped on Sat, 23 February 2008 23:23
		Re: Optimized memcmp for x86 By: mirek on Tue, 26 February 2008 22:07
		Re: Optimized memcmp for x86 By: mr_ped on Wed, 27 February 2008 11:43
		Re: Optimized memcmp for x86 By: mirek on Wed, 12 March 2008 21:27

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