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Patch [1/1] minor bugfix in 2.6.26/arch/x86/mm/pat.c - caused problems in mmap() of /dev/mem character file

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From: V.Radhakrishnan <rk@...>
To: <Linux-kernel@...>
Cc: <torvalds@...>
Subject: Patch [1/1] minor bugfix in 2.6.26/arch/x86/mm/pat.c - caused problems in mmap() of /dev/mem character file
Date: Thursday, July 17, 2008 - 1:25 pm

FROM: V.Radhakrishnan <rk@atr-labs.com>

Description:

This is a 1-line bugfix !

The program linux-2.6.26/arch/x86/mm/pat.c has the following code

#ifdef CONFIG_NONPROMISC_DEVMEM
/* This check is done in drivers/char/mem.c in case of
NONPROMISC_DEVMEM*/
static inline int range_is_allowed(unsigned long pfn, unsigned long
size)
{
	return 1;
}
#else { ... }

The above #ifdef must be actually #ifndef and not #ifdef
The bug does not allow a valid user (root) from accessing /dev/mem even
though the CONFIG_PROMISC_DEVMEM is NOT selected.

Actual patch for fix follows ...

------

--- arch/x86/mm/pat.c.orig	2008-07-17 22:04:18.000000000 +0530
+++ arch/x86/mm/pat.c	2008-07-17 22:43:39.000000000 +0530
@@ -5,7 +5,11 @@
  *          Suresh B Siddha <suresh.b.siddha@intel.com>
  *
  * Loosely based on earlier PAT patchset from Eric Biederman and Andi
Kleen.
- */
+ *
+ * Bug fixed - V. Radhakrishnan <rk@atr-labs.com> on 17-07-2008
+		#ifdef CONFIG_NONPROMISC_DEVMEM changed to
+		#ifndef CONFIG_NONPROMISC_DEVMEM
+*/
 
 #include <linux/mm.h>
 #include <linux/kernel.h>
@@ -471,7 +475,7 @@ pgprot_t phys_mem_access_prot(struct fil
 	return vma_prot;
 }
 
-#ifdef CONFIG_NONPROMISC_DEVMEM
+#ifndef CONFIG_NONPROMISC_DEVMEM
 /* This check is done in drivers/char/mem.c in case of
NONPROMISC_DEVMEM*/
 static inline int range_is_allowed(unsigned long pfn, unsigned long
size)
 {
@@ -586,4 +590,3 @@ void unmap_devmem(unsigned long pfn, uns
 
 	free_memtype(addr, addr + size);
 }
-
Signed-off-by: Radhakrishnan <rk@atr-labs.com>



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Messages in current thread:
Patch [1/1] minor bugfix in 2.6.26/arch/x86/mm/pat.c - cause..., V.Radhakrishnan, (Thu Jul 17, 1:25 pm)
Re: Patch [1/1] minor bugfix in 2.6.26/arch/x86/mm/pat.c - c..., Linus Torvalds, (Thu Jul 17, 1:27 pm)
Re: Patch [1/1] minor bugfix in 2.6.26/arch/x86/mm/pat.c - c..., Arjan van de Ven, (Sat Jul 19, 6:47 pm)
Re: Patch [1/1] minor bugfix in 2.6.26/arch/x86/mm/pat.c - c..., Ingo Molnar, (Sun Jul 20, 2:37 am)
Re: Patch [1/1] minor bugfix in 2.6.26/arch/x86/mm/pat.c - c..., Ingo Molnar, (Thu Jul 17, 6:39 pm)
Re: Patch [1/1] minor bugfix in 2.6.26/arch/x86/mm/pat.c - c..., V.Radhakrishnan, (Thu Jul 17, 10:04 pm)
Re: Patch [1/1] minor bugfix in 2.6.26/arch/x86/mm/pat.c - c..., Arjan van de Ven, (Sat Jul 19, 6:05 pm)
Re: Patch [1/1] minor bugfix in 2.6.26/arch/x86/mm/pat.c - c..., V.Radhakrishnan, (Sun Jul 20, 11:50 am)
Re: Patch [1/1] minor bugfix in 2.6.26/arch/x86/mm/pat.c - c..., Arjan van de Ven, (Sun Jul 20, 11:56 am)