linux-kernel - Re: [PATCH] mm/zsmalloc: prevent integer overflow in obj

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Message-ID: <w7ralg6gzp6kuqwulpczs7uv4htllt2rasuto5unoy7xasr5cv@2z6pd7syyj6q>
Date: Thu, 13 Mar 2025 23:42:12 +0900
From: Sergey Senozhatsky <senozhatsky@...omium.org>
To: Anastasia Belova <abelova@...ralinux.ru>
Cc: Minchan Kim <minchan@...nel.org>, 
	Sergey Senozhatsky <senozhatsky@...omium.org>, Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org, 
	linux-kernel@...r.kernel.org, lvc-project@...uxtesting.org
Subject: Re: [PATCH] mm/zsmalloc: prevent integer overflow in obj_free

On (25/03/13 14:51), Anastasia Belova wrote:
> The result of multiplication of class_size and f_objidx
> may not fit unsigned integer. Add explicit casting to
> unsigned long to prevent integer overflow.

I can't see how this can be possible.  Neither size_class nor
object idx can take values to cause mul overflow.