[Bug libc/9813] pselect implementation (when not implemneted by the kernel) agriviates the race

[Bug libc/9813] pselect implementation (when not implemneted by the kernel) agriviates the race

[mtk.manpages at gmail dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=9813

Michael Kerrisk <mtk.manpages at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mtk.manpages at gmail dot
                   |                            |com

--- Comment #4 from Michael Kerrisk <mtk.manpages at gmail dot com> 2012-02-19 22:06:49 UTC ---
Shachar, I suspect that it's not worth trying to make the fix you suggest. The
fix will only appear in modern glibc, and any modern system will have a
kernel-supported. The fundamental problem can't be remedied: the idea to add a
userspace implementation of pselect() was extremely muddleheaded, and worsens
portability problems for applications. The portability question goes from being
"do I have pselect() or not?" to "do I have a pselect() or not, and if I do, is
it one that works?"; the last part of the second question can only be verified
with a check of the kernel (and glibc) versions.

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[Bug libc/9813] pselect implementation (when not implemneted by the kernel) agriviates the race

[schwab@linux-m68k.org]

http://sourceware.org/bugzilla/show_bug.cgi?id=9813

Andreas Schwab <schwab@linux-m68k.org> changed:

           What    |Removed                     |Added
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         AssignedTo|drepper.fsp at gmail dot    |unassigned at sourceware
                   |com                         |dot org

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[Bug libc/9813] pselect implementation (when not implemneted by the kernel) agriviates the race

[neleai at seznam dot cz]

https://sourceware.org/bugzilla/show_bug.cgi?id=9813

Ondrej Bilka <neleai at seznam dot cz> changed:

           What    |Removed                     |Added
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             Status|NEW                         |RESOLVED
                 CC|                            |neleai at seznam dot cz
         Resolution|---                         |FIXED

--- Comment #5 from Ondrej Bilka <neleai at seznam dot cz> ---
As according to http://lwn.net/Articles/176911/ pselect apperared at 2.6.16 and
required kernel version is 2.6.16 this patch is moot now.

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[Bug libc/9813] pselect implementation (when not implemneted by the kernel) agriviates the race

[jsm28 at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=9813

Joseph Myers <jsm28 at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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             Status|RESOLVED                    |REOPENED
         Resolution|FIXED                       |---

--- Comment #6 from Joseph Myers <jsm28 at gcc dot gnu.org> ---
On various architectures, pselect was only added in later kernel versions. 
Please carefully check *all* kernel-features.h files in glibc, or kernel
sources of appropriate versions for *all* architectures, before making
assertions about syscall availability.  News sources likely to focus mainly on
x86 are not sufficient.

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Re: [Bug libc/9813] pselect implementation (when not implemneted by the kernel) agriviates the race

[Ondřej Bílka]

On Mon, Oct 14, 2013 at 02:24:37PM +0000, jsm28 at gcc dot gnu.org wrote:
> https://sourceware.org/bugzilla/show_bug.cgi?id=9813
> 
> Joseph Myers <jsm28 at gcc dot gnu.org> changed:
> 
>            What    |Removed                     |Added
> ----------------------------------------------------------------------------
>              Status|RESOLVED                    |REOPENED
>          Resolution|FIXED                       |---
> 
> --- Comment #6 from Joseph Myers <jsm28 at gcc dot gnu.org> ---
> On various architectures, pselect was only added in later kernel versions. 
> Please carefully check *all* kernel-features.h files in glibc, or kernel
> sources of appropriate versions for *all* architectures, before making
> assertions about syscall availability.  News sources likely to focus mainly on
> x86 are not sufficient.
 
Then patch in bugzilla is still valid. Could you review it and send to
libc-alpha?

[Bug libc/9813] pselect implementation (when not implemneted by the kernel) agriviates the race

[neleai at seznam dot cz]

http://sourceware.org/bugzilla/show_bug.cgi?id=9813

--- Comment #7 from Ondrej Bilka <neleai at seznam dot cz> ---
On Mon, Oct 14, 2013 at 02:24:37PM +0000, jsm28 at gcc dot gnu.org wrote:
> https://sourceware.org/bugzilla/show_bug.cgi?id=9813
> 
> Joseph Myers <jsm28 at gcc dot gnu.org> changed:
> 
>            What    |Removed                     |Added
> ----------------------------------------------------------------------------
>              Status|RESOLVED                    |REOPENED
>          Resolution|FIXED                       |---
> 
> --- Comment #6 from Joseph Myers <jsm28 at gcc dot gnu.org> ---
> On various architectures, pselect was only added in later kernel versions. 
> Please carefully check *all* kernel-features.h files in glibc, or kernel
> sources of appropriate versions for *all* architectures, before making
> assertions about syscall availability.  News sources likely to focus mainly on
> x86 are not sufficient.

Then patch in bugzilla is still valid. Could you review it and send to
libc-alpha?

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[Bug libc/9813] pselect implementation (when not implemneted by the kernel) agriviates the race

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=9813

Florian Weimer <fweimer at redhat dot com> changed:

           What    |Removed                     |Added
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              Flags|                            |security-

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[Bug libc/9813] pselect implementation (when not implemneted by the kernel) agriviates the race

[shachar at shemesh dot biz]

------- Additional Comments From shachar at shemesh dot biz  2009-02-04 10:52 -------
Created an attachment (id=3712)
 --> (http://sourceware.org/bugzilla/attachment.cgi?id=3712&action=view)
Program demonstrating the problem

This program demonstrate the problem. Under a kernel with pselect support, it
prints:
sig_happened=1
sig_happened=1
sig_happened=1
sig_happened=1
sig_happened=1

And exits almost immediately.

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[Bug libc/9813] pselect implementation (when not implemneted by the kernel) agriviates the race

[shachar at shemesh dot biz]

------- Additional Comments From shachar at shemesh dot biz  2009-02-04 10:42 -------
Forgot to add - in the above patch, NSIG_LONGS is undefined. Here is its definition:

// Number of __vals in sigset_t that actually contain useful data
#define NSIG_LONGS (_NSIG/(8*sizeof(((sigset_t *)NULL)->__val[0])))

Shachar

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[Bug libc/9813] pselect implementation (when not implemneted by the kernel) agriviates the race

[shachar at shemesh dot biz]

------- Additional Comments From shachar at shemesh dot biz  2009-02-04 10:36 -------
Created an attachment (id=3710)
 --> (http://sourceware.org/bugzilla/attachment.cgi?id=3710&action=view)
Proposed patch to narrow the race window

Proposed patch to the problem

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