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Re: [PATCH 10/13] xfs: use get_unused_fd_flags(0) instead of get_unused_

To: Yann Droneaud <ydroneaud@xxxxxxxxxx>
Subject: Re: [PATCH 10/13] xfs: use get_unused_fd_flags(0) instead of get_unused_fd()
From: Ben Myers <bpm@xxxxxxx>
Date: Mon, 8 Jul 2013 17:41:33 -0500
Cc: linux-kernel@xxxxxxxxxxxxxxx, xfs@xxxxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <8d21b76c621dbfc59b2dbbfc933f96170835304d.1372777600.git.ydroneaud@xxxxxxxxxx>
References: <cover.1372777600.git.ydroneaud@xxxxxxxxxx> <8d21b76c621dbfc59b2dbbfc933f96170835304d.1372777600.git.ydroneaud@xxxxxxxxxx>
User-agent: Mutt/1.5.20 (2009-06-14)
On Tue, Jul 02, 2013 at 06:39:34PM +0200, Yann Droneaud wrote:
> Macro get_unused_fd() is used to allocate a file descriptor with
> default flags. Those default flags (0) can be "unsafe":
> O_CLOEXEC must be used by default to not leak file descriptor
> across exec().
> 
> Instead of macro get_unused_fd(), functions anon_inode_getfd()
> or get_unused_fd_flags() should be used with flags given by userspace.
> If not possible, flags should be set to O_CLOEXEC to provide userspace
> with a default safe behavor.
> 
> In a further patch, get_unused_fd() will be removed so that
> new code start using anon_inode_getfd() or get_unused_fd_flags()
> with correct flags.
> 
> This patch replaces calls to get_unused_fd() with equivalent call to
> get_unused_fd_flags(0) to preserve current behavor for existing code.
> 
> The hard coded flag value (0) should be reviewed on a per-subsystem basis,
> and, if possible, set to O_CLOEXEC.
> 
> Signed-off-by: Yann Droneaud <ydroneaud@xxxxxxxxxx>
>
> ---
>  fs/xfs/xfs_ioctl.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
> index 5e99968..dc5b659 100644
> --- a/fs/xfs/xfs_ioctl.c
> +++ b/fs/xfs/xfs_ioctl.c
> @@ -248,7 +248,7 @@ xfs_open_by_handle(
>               goto out_dput;
>       }
>  
> -     fd = get_unused_fd();
> +     fd = get_unused_fd_flags(0);

O_CLOEXEC should be fine in this case.

Reviewed-by: Ben Myers <bpm@xxxxxxx>

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