linux-kernel - Re: [PATCH v6 3/6] fs/procfs: add build ID fetching to PROCMAP

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Message-ID: <Zn86IUVaFh7rqS2I@tassilo>
Date: Fri, 28 Jun 2024 15:33:05 -0700
From: Andi Kleen <ak@...ux.intel.com>
To: Andrii Nakryiko <andrii.nakryiko@...il.com>
Cc: Andrii Nakryiko <andrii@...nel.org>, linux-fsdevel@...r.kernel.org,
	brauner@...nel.org, viro@...iv.linux.org.uk,
	akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
	bpf@...r.kernel.org, gregkh@...uxfoundation.org, linux-mm@...ck.org,
	liam.howlett@...cle.com, surenb@...gle.com, rppt@...nel.org,
	adobriyan@...il.com
Subject: Re: [PATCH v6 3/6] fs/procfs: add build ID fetching to PROCMAP_QUERY
 API

> Yep, makes sense. I'm currently reworking this whole lib/buildid.c
> implementation to remove all the restrictions on data being in the
> first page only, and making it work in a faultable context more
> reliably. I can audit the code for TOCTOU issues and incorporate your
> feedback. I'll probably post the patch set next week, will cc you as
> well.

Please also add checks that the mapping is executable, to
close the obscure "can check the first 4 bytes of every mapped 
file is ELF\0" hole.

But it will still need the hardening because mappings from
ld.so are not EBUSY for writes.

-Andi