From: Al Viro <viro@zeniv.linux.org.uk>
To: Daniel Rosenberg <drosen@google.com>
Cc: Theodore Ts'o <tytso@mit.edu>,
linux-ext4@vger.kernel.org, Jaegeuk Kim <jaegeuk@kernel.org>,
Chao Yu <chao@kernel.org>,
linux-f2fs-devel@lists.sourceforge.net,
Eric Biggers <ebiggers@kernel.org>,
linux-fscrypt@vger.kernel.org,
Richard Weinberger <richard@nod.at>,
linux-mtd@lists.infradead.org,
Andreas Dilger <adilger.kernel@dilger.ca>,
Jonathan Corbet <corbet@lwn.net>,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-fsdevel@vger.kernel.org,
Gabriel Krisman Bertazi <krisman@collabora.com>,
kernel-team@android.com
Subject: Re: [PATCH v7 2/8] fs: Add standard casefolding support
Date: Mon, 10 Feb 2020 23:42:07 +0000 [thread overview]
Message-ID: <20200210234207.GJ23230@ZenIV.linux.org.uk> (raw)
In-Reply-To: <CA+PiJmTYbEA-hgrKwtp0jZXqsfYrzgogOZ0Pt=gTCtqhBfnqFA@mail.gmail.com>
On Mon, Feb 10, 2020 at 03:11:13PM -0800, Daniel Rosenberg wrote:
> On Fri, Feb 7, 2020 at 6:12 PM Al Viro <viro@zeniv.linux.org.uk> wrote:
> >
> > On Fri, Feb 07, 2020 at 05:35:46PM -0800, Daniel Rosenberg wrote:
> >
> >
> > Again, is that safe in case when the contents of the string str points to
> > keeps changing under you?
>
> I'm not sure what you mean. I thought it was safe to use the str and
> len passed into d_compare. Even if it gets changed under RCU
> conditions I thought there was some code to ensure that the name/len
> pair passed in is consistent, and any other inconsistencies would get
> caught by d_seq later. Are there unsafe code paths that can follow?
If you ever fetch the same byte twice, you might see different values.
You need a fairly careful use of READ_ONCE() or equivalents to make
sure that you don't get screwed over by that.
Sure, ->d_seq mismatch will throw the result out, but you need to make
sure you won't oops/step on uninitialized memory/etc. in process.
It's not impossible to get right, but it's not trivial and you need all
code working with that much more careful than normal for string handling.
next prev parent reply other threads:[~2020-02-10 23:42 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-08 1:35 [PATCH v7 0/8] Support fof Casefolding and Encryption Daniel Rosenberg
2020-02-08 1:35 ` [PATCH v7 1/8] unicode: Add utf8_casefold_iter Daniel Rosenberg
2020-02-12 3:38 ` Eric Biggers
2020-02-14 21:47 ` Daniel Rosenberg
2020-02-17 19:02 ` Gabriel Krisman Bertazi
2020-02-08 1:35 ` [PATCH v7 2/8] fs: Add standard casefolding support Daniel Rosenberg
2020-02-08 2:12 ` Al Viro
2020-02-10 23:11 ` Daniel Rosenberg
2020-02-10 23:42 ` Al Viro [this message]
2020-02-12 6:34 ` Eric Biggers
2020-02-12 6:57 ` Eric Biggers
2020-02-20 2:27 ` Daniel Rosenberg
2020-02-12 3:55 ` Eric Biggers
2020-02-08 1:35 ` [PATCH v7 3/8] f2fs: Use generic " Daniel Rosenberg
2020-02-12 4:05 ` Eric Biggers
2020-02-08 1:35 ` [PATCH v7 4/8] ext4: " Daniel Rosenberg
2020-02-08 1:35 ` [PATCH v7 5/8] fscrypt: Have filesystems handle their d_ops Daniel Rosenberg
2020-02-12 4:33 ` Eric Biggers
2020-02-08 1:35 ` [PATCH v7 6/8] f2fs: Handle casefolding with Encryption Daniel Rosenberg
2020-02-12 5:10 ` Eric Biggers
2020-02-12 5:55 ` Al Viro
2020-02-12 6:06 ` Eric Biggers
2020-02-12 5:47 ` Eric Biggers
2020-02-08 1:35 ` [PATCH v7 7/8] ext4: Hande casefolding with encryption Daniel Rosenberg
2020-02-12 5:59 ` Eric Biggers
2020-02-08 1:35 ` [PATCH v7 8/8] ext4: Optimize match for casefolded encrypted dirs Daniel Rosenberg
2020-02-12 6:12 ` [PATCH v7 0/8] Support fof Casefolding and Encryption Eric Biggers
2020-02-13 0:01 ` Daniel Rosenberg
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