linux-ext4 - Re: [PATCH] ext4: extents: Remove unnecessary ‘NULL’ values from path

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <20240402035502.GC1189142@mit.edu>
Date: Mon, 1 Apr 2024 23:55:02 -0400
From: "Theodore Ts'o" <tytso@....edu>
To: Li zeming <zeming@...china.com>
Cc: adilger.kernel@...ger.ca, linux-ext4@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ext4: extents: Remove unnecessary ‘NULL’ values from path

On Tue, Apr 02, 2024 at 10:41:40AM +0800, Li zeming wrote:
> path is assigned first, so it does not need to initialize the
> assignment.

That's technically true, but the compiler is perfectly capable of
optimizing it out.  So it's harmless, and removing it does make the
code a bit more fragile, since it needs to be set so that the cleanup
code doesn't accidentally dereference an uninitialized pointer:

out:
	up_read(&ei->i_data_sem);
	ext4_free_ext_path(path);
	return ret;

So if later on, we add code which does a "goto out" on an error,
before path gets initialized, that would be bad.  So removing the
"unnecessary" set has no upside, and it has a potential disadvantage.

	      	      	 	     - Ted