linux-kernel - Re: [PATCH] Bug fix to ELF Loader which rejects valid ELFs

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Message-ID: <20200811150517.GR17456@casper.infradead.org>
Date:   Tue, 11 Aug 2020 16:05:17 +0100
From:   Matthew Wilcox <willy@...radead.org>
To:     "Burrow, Ryan - 0553 - MITLL" <Ryan.Burrow@...mit.edu>
Cc:     "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] Bug fix to ELF Loader which rejects valid ELFs

On Tue, Aug 11, 2020 at 02:44:08PM +0000, Burrow, Ryan - 0553 - MITLL wrote:
>  	/* Sanity check the number of program headers... */
> -	/* ...and their total size. */
> -	size = sizeof(struct elf_phdr) * elf_ex->e_phnum;
> -	if (size == 0 || size > 65536 || size > ELF_MIN_ALIGN)
> +	if (elf_ex->e_phnum == 0 || elf_ex->phnum > 65535)

umm, did you compile-test this?

assuming you meant e_phnum, it's a 16-bit quantity, so it can't be bigger
than 65535.

>  		goto out;
>  
> +	size = sizeof(struct elf_phdr) * elf_ex->e_phnum;

use array_size() here?