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* [PATCH] DEV: zero: use correct pgprot for zeromapping
@ 2007-02-10  9:15 Imre Deak
  2007-02-10  9:39 ` Russell King
  0 siblings, 1 reply; 4+ messages in thread
From: Imre Deak @ 2007-02-10  9:15 UTC (permalink / raw)
  To: linux-kernel; +Cc: rmk

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;

^ permalink raw reply	[flat|nested] 4+ messages in thread

end of thread, other threads:[~2007-02-10 17:30 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2007-02-10  9:15 [PATCH] DEV: zero: use correct pgprot for zeromapping Imre Deak
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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