[3.16.y-ckt stable] Patch "mm/memory.c: actually remap enough memory" has been added to staging queue

Luis Henriques luis.henriques at canonical.com
Mon Mar 2 13:37:31 UTC 2015

This is a note to let you know that I have just added a patch titled

    mm/memory.c: actually remap enough memory

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:


This patch is scheduled to be released in version 3.16.7-ckt8.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see



>From d8e90669301b7bc8920300d89bbb7312f71458e1 Mon Sep 17 00:00:00 2001
From: Grazvydas Ignotas <notasas at gmail.com>
Date: Thu, 12 Feb 2015 15:00:19 -0800
Subject: mm/memory.c: actually remap enough memory

commit 9cb12d7b4ccaa976f97ce0c5fd0f1b6a83bc2a75 upstream.

For whatever reason, generic_access_phys() only remaps one page, but
actually allows to access arbitrary size.  It's quite easy to trigger
large reads, like printing out large structure with gdb, which leads to a
crash.  Fix it by remapping correct size.

Fixes: 28b2ee20c7cb ("access_process_vm device memory infrastructure")
Signed-off-by: Grazvydas Ignotas <notasas at gmail.com>
Cc: Rik van Riel <riel at redhat.com>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
 mm/memory.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/memory.c b/mm/memory.c
index 769bc8906b2d..e7ae35a5ffeb 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3566,7 +3566,7 @@ int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
 	if (follow_phys(vma, addr, write, &prot, &phys_addr))
 		return -EINVAL;

-	maddr = ioremap_prot(phys_addr, PAGE_SIZE, prot);
+	maddr = ioremap_prot(phys_addr, PAGE_ALIGN(len + offset), prot);
 	if (write)
 		memcpy_toio(maddr + offset, buf, len);

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