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From: Imre Deak <>
Subject: [PATCH] DEV: zero: use correct pgprot for zeromapping
Date: Sat, 10 Feb 2007 11:15:21 +0200	[thread overview]
Message-ID: <> (raw)

Instead of PAGE_COPY use the pgprot bits established already at
original mapping time of the VMA. This will also include any
architecture specific bits setup through protection_map.
zeromap_page_range will take care of COW'ing the passed pgprot.

This fixes at least one problem on ARM where reading /dev/zero
in one process created global PTE mappings thus - practically -
zeroing out memory ranges of all other processes.

Signed-off-by: Imre Deak <>
 drivers/char/mem.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index f5c160c..9a7264f 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -646,7 +646,7 @@ static inline size_t read_zero_pagealigned(char __user * buf, size_t size)
 			count = size;
 		zap_page_range(vma, addr, count, NULL);
-        	if (zeromap_page_range(vma, addr, count, PAGE_COPY))
+        	if (zeromap_page_range(vma, addr, count, vma->vm_page_prot))
 		size -= count;

             reply	other threads:[~2007-02-10  9:39 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-02-10  9:15 Imre Deak [this message]
2007-02-10  9:39 ` Russell King
2007-02-10 10:03   ` Imre Deak
2007-02-10 17:29     ` [PATCH] ARM: VM: fix user page protection values (was Re: [PATCH] DEV: zero: use correct pgprot for zeromapping) Imre Deak

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