From: Kees Cook <keescook@chromium.org>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: "Guilherme G. Piccoli" <gpiccoli@igalia.com>,
Tony Luck <tony.luck@intel.com>,
linux-hardening@vger.kernel.org,
Christian Brauner <brauner@kernel.org>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 5/5] pstore: inode: Use cleanup.h for struct pstore_private
Date: Mon, 4 Dec 2023 16:54:25 -0800 [thread overview]
Message-ID: <202312041649.C14F139F9@keescook> (raw)
In-Reply-To: <20231202222706.GT38156@ZenIV>
On Sat, Dec 02, 2023 at 10:27:06PM +0000, Al Viro wrote:
> On Sat, Dec 02, 2023 at 01:22:15PM -0800, Kees Cook wrote:
>
> > static void *pstore_ftrace_seq_start(struct seq_file *s, loff_t *pos)
> > {
> > @@ -338,9 +339,8 @@ int pstore_mkfile(struct dentry *root, struct pstore_record *record)
> > {
> > struct dentry *dentry;
> > struct inode *inode __free(iput) = NULL;
> > - int rc = 0;
> > char name[PSTORE_NAMELEN];
> > - struct pstore_private *private, *pos;
> > + struct pstore_private *private __free(pstore_private) = NULL, *pos;
> > size_t size = record->size + record->ecc_notice_size;
> >
> > if (WARN_ON(!inode_is_locked(d_inode(root))))
> > @@ -356,7 +356,6 @@ int pstore_mkfile(struct dentry *root, struct pstore_record *record)
> > return -EEXIST;
> > }
> >
> > - rc = -ENOMEM;
> > inode = pstore_get_inode(root->d_sb);
> > if (!inode)
> > return -ENOMEM;
> > @@ -373,7 +372,7 @@ int pstore_mkfile(struct dentry *root, struct pstore_record *record)
> >
> > dentry = d_alloc_name(root, name);
> > if (!dentry)
> > - goto fail_private;
> > + return -ENOMEM;
> >
> > private->dentry = dentry;
> > private->record = record;
> > @@ -386,13 +385,9 @@ int pstore_mkfile(struct dentry *root, struct pstore_record *record)
> >
> > d_add(dentry, no_free_ptr(inode));
> >
> > - list_add(&private->list, &records_list);
> > + list_add(&(no_free_ptr(private))->list, &records_list);
>
> That's really brittle. It critically depends upon having no failure
> exits past the assignment to ->i_private; once you've done that,
> you have transferred the ownership of that thing to the inode
> (look at your ->evict_inode()).
I guess so, but it was already that way, and it isn't assignment to
i_private until everything else is "done", apart from adding to the
dentry and the pstore internal list.
> But you can't say
> inode->i_private = no_free_ptr(private);
> since you are using private past that point.
True. How about this reordering:
if (record->time.tv_sec)
inode_set_mtime_to_ts(inode,
inode_set_ctime_to_ts(inode, record->time));
list_add(&private->list, &records_list);
inode->i_private = no_free_ptr(private);
d_add(dentry, no_free_ptr(inode));
But none of this gets into how you'd like to see the iput handled. If
you'd prefer, I can just define a pstore_iput handler and you don't have
to look at it at all. :)
-Kees
--
Kees Cook
prev parent reply other threads:[~2023-12-05 0:54 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-02 21:22 [PATCH 0/5] pstore: Initial use of cleanup.h Kees Cook
2023-12-02 21:22 ` [PATCH 1/5] pstore: inode: Convert kfree() usage to __free(kfree) Kees Cook
2023-12-02 21:22 ` [PATCH 2/5] pstore: inode: Convert mutex usage to guard(mutex) Kees Cook
2023-12-05 7:01 ` Dave Chinner
2023-12-02 21:22 ` [PATCH 3/5] fs: Add DEFINE_FREE for struct inode Kees Cook
2023-12-02 21:28 ` Al Viro
2023-12-02 21:34 ` Kees Cook
2023-12-02 21:42 ` Al Viro
2023-12-02 21:45 ` Al Viro
2023-12-05 11:38 ` Christian Brauner
2023-12-02 21:22 ` [PATCH 4/5] pstore: inode: Use __free(iput) for inode allocations Kees Cook
2023-12-02 21:22 ` [PATCH 5/5] pstore: inode: Use cleanup.h for struct pstore_private Kees Cook
2023-12-02 22:27 ` Al Viro
2023-12-05 0:54 ` Kees Cook [this message]
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