From: Al Viro <viro@ZenIV.linux.org.uk>
To: Andy Lutomirski <luto@kernel.org>
Cc: Linux FS Devel <linux-fsdevel@vger.kernel.org>,
Stephen Rothwell <sfr@canb.auug.org.au>,
Andrew Morton <akpm@linux-foundation.org>,
stable@vger.kernel.org,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH v2 1/2] fs: Improve and simplify copy_mount_options
Date: Thu, 16 Jun 2016 00:50:47 +0100 [thread overview]
Message-ID: <20160615235047.GA14480@ZenIV.linux.org.uk> (raw)
In-Reply-To: <f2ad616567c7666cbba22f51c97fac1d09cfd200.1465871650.git.luto@kernel.org>
On Mon, Jun 13, 2016 at 07:36:04PM -0700, Andy Lutomirski wrote:
> copy_mount_options always tries to copy a full page even if the
> string is shorter than a page. If the string starts part-way into a
> page and ends on the same page it started on, this means that
> copy_mount_options can overrun the supplied buffer and read into the
> next page.
Have you considered the possibility that there might be a reason for
having separate copy_mount_option() and copy_mount_string()? Such as
options not being a string, perhaps?
In some filesystems (including older NFS variants) it is not a string
at all - a binary data structure, with quite a few zero bytes in it.
And no, we fucking *can't* break mount.nfs(8), no matter how we'd like
to get rid of that wart of an ABI.
IOW, NAK with prejudice - don't bring that thing back, it's hard no-go.
next prev parent reply other threads:[~2016-06-15 23:50 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-14 2:36 [PATCH v2 0/2] copy_mount_options improvements Andy Lutomirski
2016-06-14 2:36 ` [PATCH v2 1/2] fs: Improve and simplify copy_mount_options Andy Lutomirski
2016-06-15 23:50 ` Al Viro [this message]
2016-06-16 0:01 ` Andy Lutomirski
2016-06-16 0:42 ` Linus Torvalds
2016-06-16 5:45 ` Willy Tarreau
2016-06-16 5:59 ` Linus Torvalds
2016-06-16 6:57 ` Willy Tarreau
2016-06-16 7:02 ` Willy Tarreau
2016-06-16 7:08 ` Al Viro
2016-06-16 7:25 ` Willy Tarreau
2016-06-16 8:02 ` Al Viro
2016-06-16 8:20 ` Willy Tarreau
2016-06-16 8:38 ` Willy Tarreau
2016-06-17 3:12 ` Andy Lutomirski
2016-06-14 2:36 ` [PATCH v2 2/2] fs: Disallow mount options strings longer than PAGE_SIZE - 1 Andy Lutomirski
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