Re: Unchecked flags in statx(2) [Should be fixed before 4.11-final?]

From	David Howells <dhowells@redhat.com>
Newsgroups	linux.kernel
Subject	Re: Unchecked flags in statx(2) [Should be fixed before 4.11-final?]
Date	2017-04-21 14:50 +0200
Message-ID	<tyGaB-5Ri-5@gated-at.bofh.it> (permalink)
References	<tyFHz-5HC-1@gated-at.bofh.it>
Organization	Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903

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Michael Kerrisk (man-pages) <mtk.manpages@gmail.com> wrote:

>  I was reading your statx(2) man page, and noticed this text:
> 
>        Do not simply set mask to UINT_MAX as one or more bits may, in the
>        future, be used to specify an extension to the buffer.
> 
> (Here' 'mask' is the fourth argument to statx())
> 
> What is going on here? Why is there  not a check in the code to
> give EINVAL if any flag other than those in STATX_ALL (0x00000fffU)
> is specified? (There is a check that gives EINVAL flags in 
> STATX__RESERVED (0x80000000U), but STATX_ALL != ~STATX__RESERVED.

Yeah, I need to update that.  I sent you the manpage to have a look at before
the patch that added the reservation got merged - possibly before I even wrote
that patch.

> Similarly, there appears to be no check for invalid flags in the
> 'flags' argument of statx(). Why is there also not such a check
> there?

Like this?

	if (mask & STATX__RESERVED)
		return -EINVAL;

David

Thread

Unchecked flags in statx(2) [Should be fixed before 4.11-final?] "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com> - 2017-04-21 14:20 +0200
  Re: Unchecked flags in statx(2) [Should be fixed before 4.11-final?] "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com> - 2017-04-21 14:30 +0200
  Re: Unchecked flags in statx(2) [Should be fixed before 4.11-final?] David Howells <dhowells@redhat.com> - 2017-04-21 14:50 +0200
  Re: Unchecked flags in statx(2) [Should be fixed before 4.11-final?] David Howells <dhowells@redhat.com> - 2017-04-21 14:50 +0200
  Re: Unchecked flags in statx(2) [Should be fixed before 4.11-final?] David Howells <dhowells@redhat.com> - 2017-04-21 15:10 +0200
    Re: Unchecked flags in statx(2) [Should be fixed before 4.11-final?] "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com> - 2017-04-21 15:20 +0200
      Re: Unchecked flags in statx(2) [Should be fixed before 4.11-final?] Andreas Dilger <adilger@dilger.ca> - 2017-04-21 20:50 +0200
        Re: Unchecked flags in statx(2) [Should be fixed before 4.11-final?] "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com> - 2017-04-21 21:20 +0200

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