linux-kernel - Re: [PATCH] module: fix [e_shstrndx].sh

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Date:   Wed, 4 May 2022 12:50:43 +0300
From:   Alexey Dobriyan <adobriyan@...il.com>
To:     Luis Chamberlain <mcgrof@...nel.org>
Cc:     akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
        linux-modules@...r.kernel.org
Subject: Re: [PATCH] module: fix [e_shstrndx].sh_size=0 OOB access

On Tue, May 03, 2022 at 01:15:04PM -0700, Luis Chamberlain wrote:
> On Tue, May 03, 2022 at 05:57:59PM +0300, Alexey Dobriyan wrote:
> > It is trivial to craft a module to trigger OOB access in this line:
> > 
> > 	if (info->secstrings[strhdr->sh_size - 1] != '\0') {
> > 
> > BUG: unable to handle page fault for address: ffffc90000aa0fff
> > #PF: supervisor read access in kernel mode
> > #PF: error_code(0x0000) - not-present page
> > PGD 100000067 P4D 100000067 PUD 100066067 PMD 10436f067 PTE 0
> > Oops: 0000 [#1] PREEMPT SMP PTI
> > CPU: 7 PID: 1215 Comm: insmod Not tainted 5.18.0-rc5-00007-g9bf578647087-dirty #10
> > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-4.fc34 04/01/2014
> > RIP: 0010:load_module+0x19b/0x2391
> > 
> > Signed-off-by: Alexey Dobriyan <adobriyan@...il.com>
> 
> Thanks! Can you resend and Cc stable?

Stable will pick it up simply because patch does apply I assume?

> This seems like an issue present for
> a long time, can you identify the commit which introduced the issue?

I thought it was ancient code but no.