From: Dominique Martinet <asmadeus@codewreck.org>
To: Hui Peng <benquike@gmail.com>
Cc: ericvh@kernel.org, lucho@ionkov.net, linux_oss@crudebyte.com,
v9fs@lists.linux.dev, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] 9p: reject RERROR/RLERROR with zero errcode and guard 0-link drop_nlink()
Date: Tue, 22 Sep 2026 17:47:37 +0900 [thread overview]
Message-ID: <arJAqVPrm1XfL1w-@codewreck.org> (raw)
In-Reply-To: <20260919221734.3708000-1-benquike@gmail.com>
Hui Peng wrote on Sat, Sep 19, 2026 at 10:17:34PM +0000:
> Fix two issues in 9p client and VFS inode handling:
Please split this in two commits.
> 1. In p9_check_errors() (net/9p/client.c), a malicious or buggy 9p
> server returning P9_RERROR or P9_RLERROR with ecode == 0 causes
> p9_check_errors() to return 0 (success) while leaving the unparsed
> response payload as if the expected reply message type succeeded. Map
> ecode == 0 on RERROR / RLERROR to -EPROTO.
Sure
> 2. In v9fs_dec_count() (fs/9p/vfs_inode.c), only call drop_nlink() when
> inode->i_nlink > 0 so unlinking an inode whose server-reported nlink
> was already 0 does not underflow i_nlink and trigger
> WARN_ON(inode->i_nlink == 0).
I'm pretty sure this is racy but the dir case already is anyway, so meh,
why not, ok.
--
Dominique Martinet | Asmadeus
prev parent reply other threads:[~2026-09-22 8:47 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-19 22:17 [PATCH] 9p: reject RERROR/RLERROR with zero errcode and guard 0-link drop_nlink() Hui Peng
2026-09-22 8:47 ` Dominique Martinet [this message]
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