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	Thu, 25 Sep 2025 19:36:47 +0000
Date: Thu, 25 Sep 2025 20:36:47 +0100
From: Al Viro <viro@zeniv.linux.org.uk>
To: Jan Kara <jack@suse.cz>
Cc: linux-fsdevel@vger.kernel.org,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Christian Brauner <brauner@kernel.org>,
	Amir Goldstein <amir73il@gmail.com>,
	Chuck Lever <chuck.lever@oracle.com>,
	Namjae Jeon <linkinjeon@kernel.org>,
	John Johansen <john@apparmor.net>, Mark Brown <broonie@kernel.org>
Subject: Re: [PATCH 1/2] kernel/acct.c: saner struct file treatment
Message-ID: <20250925193647.GB39973@ZenIV>
References: <20250906090738.GA31600@ZenIV>
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Sender: Al Viro <viro@ftp.linux.org.uk>

On Thu, Sep 25, 2025 at 08:09:44PM +0100, Al Viro wrote:

> Something like this for incremental (completely untested at that point):

BTW, that got me wondering - how about adding
	if (IS_ERR(pathname))
		return PTR_ERR(pathname);
in the very beginning of do_filp_open()?

As the result, e.g. do_open_execat() will automatically DTRT when passed
ERR_PTR(...) for name, reducing open_exec() to
struct file *open_exec(const char *name)
{
        struct filename *filename __free(putname) = getname_kernel(name);
	return do_open_execat(AT_FDCWD, filename, 0);
}

with similar effects for alloc_bprm(), etc.  The same goes for
file_open_name(), with simplified filp_open() and quite a few other
places...

Note that filename_parentat()/filename_lookupat()/etc. have the same logics
in them - do_filp_open() is the only caller of set_nameidata() that leaves
that check to its callers.

Oh, well - next cycle fodder, at that point...