linux-kernel - Re: a question regarding sys_poll() on x86

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Date:	Thu, 15 Sep 2011 15:00:55 +0200
From:	Thomas Meyer <thomas@...3r.de>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	viro@...iv.linux.org.uk, mingo@...hat.com
Subject: Re: a question regarding sys_poll() on x86_64 via tha ia32 layer

Am Donnerstag, den 15.09.2011, 14:23 +0200 schrieb Eric Dumazet:
> Its a plain bug, please submit a formal patch.
> 
> Probably not noticed because timer is set to more than 24 days.
> 

okay. I think a similar problem exists for sys_truncate() in ia32 layer
on x86_64:

the ia32 syscall is directly wired to sys_truncate(char *, long).

signed long will use %rbx on x86_64 and %ebx on x86.

call sys_truncate on x86_64 from x86 userspace will handle length
0xffffffff not as -1.

maybe an easy fix would be to change long to unsigned long for
sys_truncate(), like sys_ftruncate(). what do you think?

with kind regards
thomas

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