linux-kernel - Re: [PATCH] nfs: Fix security label length not being reset

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Message-ID: <20200915183310.GB32632@fieldses.org>
Date:   Tue, 15 Sep 2020 14:33:10 -0400
From:   bfields@...ldses.org (J. Bruce Fields)
To:     Jeffrey Mitchell <jeffrey.mitchell@...rlab.io>
Cc:     Trond Myklebust <trond.myklebust@...merspace.com>,
        Anna Schumaker <anna.schumaker@...app.com>,
        linux-nfs@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] nfs: Fix security label length not being reset

On Mon, Sep 14, 2020 at 10:49:57AM -0500, Jeffrey Mitchell wrote:
> nfs_readdir_page_filler() iterates over entries in a directory, reusing
> the same security label buffer, but does not reset the buffer's length.
> This causes decode_attr_security_label() to return -ERANGE if an entry's
> security label is longer than the previous one's. This error, in
> nfs4_decode_dirent(), only gets passed up as -EAGAIN, which causes another
> failed attempt to copy into the buffer. The second error is ignored and
> the remaining entries do not show up in ls, specifically the getdents64()
> syscall.
> 
> Reproduce by creating multiple files in NFS and giving one of the later
> files a longer security label. ls will not see that file nor any that are
> added afterwards, though they will exist on the backend.

Please include these paragraphs in the changelog.

--b.

> 
> - Jeffrey
> 
> Jeffrey Mitchell (1):
>   nfs: Fix security label length not being reset
> 
>  fs/nfs/dir.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> -- 
> 2.25.1