linux-kernel - Re: [GIT PULL] LSM fixes for v6.1 (#1)

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Message-ID: <CAHk-=wj_6Df1NAMs14S0OOqX1Z=460j-mfwn_qm-7EK1eK76qw@mail.gmail.com>
Date:   Mon, 31 Oct 2022 12:22:29 -0700
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Paul Moore <paul@...l-moore.com>
Cc:     linux-security-module@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [GIT PULL] LSM fixes for v6.1 (#1)

On Mon, Oct 31, 2022 at 4:07 AM Paul Moore <paul@...l-moore.com> wrote:
>
> A single patch to the capabilities code to fix a potential memory leak
> in the xattr allocation error handling.  Please apply for v6.1-rcX.

Pulled.

However, I react to the strange test condition. Sure, it's
pre-existing, but does it really make sense?

It does

+       if (ret < 0 || !tmpbuf) {
+               size = ret;
+               goto out_free;
+       }

and how the heck can 'tmpbuf' be NULL if vfs_getxattr_alloc() succeeded?

I think that's not only impossible in the first place, but if it *was*
possible, then that

                size = ret;
               goto out_free;

would be wrong, because this function would return success even if it
wasn't successful.

That whole "cast to int, and then cast back to size_t" also smells of
some serious confusion in the return value handling. It looks to me
like vfs_getxattr_alloc() fundamentally returns an 'int', not a
'ssize_t', just by looking at the ->get function. But it just all
looks weird.

So this code has all kinds of oddities.

               Linus