linux-kernel - Re: Regression in 2.6.25-rc3: s2ram segfaults before suspending

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Message-ID: <47C873AA.6040305@zytor.com>
Date:	Fri, 29 Feb 2008 13:05:46 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	"Klaus S. Madsen" <ksm@...rnemadsen.org>
CC:	Ingo Molnar <mingo@...e.hu>, LKML <linux-kernel@...r.kernel.org>,
	Pavel Machek <pavel@....cz>, "Rafael J. Wysocki" <rjw@...k.pl>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: Regression in 2.6.25-rc3: s2ram segfaults before suspending

Klaus S. Madsen wrote:
> open("/dev/mem", O_RDWR)                = 5
> mmap2(NULL, 1282, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_SHARED|MAP_FIXED, 5, 0) = 0
> mmap2(0xa0000, 393216, PROT_READ|PROT_WRITE, MAP_SHARED|MAP_FIXED, 5, 0xa0) = 0xa0000
                          ^^^^^^^^^^^^^^^^^^^^
> close(5)                                = 0
> ioperm(0, 0x400, 0x1)                   = 0
> iopl(0x3)                               = 0
> access("/sys/bus/pci", R_OK)            = 0
> write(1, "Calling get_mode\n", 17)      = 17
> vm86(0x1, 0xb7f14ccc, 0xb7f14830, 0xc000, 0x18b6 <unfinished ...>
> --- SIGSEGV (Segmentation fault) @ 0 (0) ---
> +++ killed by SIGSEGV (core dumped) +++

This is the VGA BIOS being mapped, it's mapped PROT_READ|PROT_WRITE, but 
  no PROT_EXEC; if the kernel is NX-capable it *should* segfault trying 
to execute out of this area, which is exactly what will happen when vm86 
executes INT 10h.

If we can find that mmap() in the s2ram source code and add PROT_EXEC to 
it, it would be interesting.

	-hpa
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