linux-kernel - Re: [PATCH] fs: Add additional checks for block devices during mount

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

Message-ID: <20250723-heizperiode-fotoreporter-2ada7fe78028@brauner>
Date: Wed, 23 Jul 2025 14:51:27 +0200
From: Christian Brauner <brauner@...nel.org>
To: Christoph Hellwig <hch@....de>
Cc: Zizhi Wo <wozizhi@...weicloud.com>, kernel test robot <lkp@...el.com>, 
	viro@...iv.linux.org.uk, jack@...e.com, axboe@...nel.dk, llvm@...ts.linux.dev, 
	oe-kbuild-all@...ts.linux.dev, linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org, 
	yukuai3@...wei.com, yangerkun@...wei.com
Subject: Re: [PATCH] fs: Add additional checks for block devices during mount

On Mon, Jul 21, 2025 at 08:47:12AM +0200, Christoph Hellwig wrote:
> On Mon, Jul 21, 2025 at 09:20:27AM +0800, Zizhi Wo wrote:
> > Sorry, disk_live() is only declared but not defined when CONFIG_BLOCK is
> > not set...
> 
> You can just add a if (IS_ENABLED(CONFIG_BLOCK)) check around it.
> 
> 
> But the layering here feels wrong.  sget_dev and it's helper operate
> purely on the dev_t.  Anything actually dealing with a block device /
> gendisk should be in the helpers that otherwise use it.

Either we add a lookup_bdev_alive() variant that checks whether the
inode is still hashed when looking up the dev_t and we accept that this
deals with the obvious cases and accept that this is racy...

Or we add lookup_bdev_no_open() that returns the block device with the
reference bumped, paired with lookup_bdev_put_no_open(). Afaiu, that
would prevent deletion. We could even put this behind a
guard(bdev_no_open)(fc->source). The reference count bump shouldn't
matter there. Christoph?