linux-kernel - [PATCH 3.2 040/221] mm/memory.c: actually remap enough memory

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Date:	Tue, 05 May 2015 02:16:39 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:	akpm@...ux-foundation.org,
	"Linus Torvalds" <torvalds@...ux-foundation.org>,
	"Grazvydas Ignotas" <notasas@...il.com>,
	"Rik van Riel" <riel@...hat.com>
Subject: [PATCH 3.2 040/221] mm/memory.c: actually remap enough memory

3.2.69-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Grazvydas Ignotas <notasas@...il.com>

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@...il.com>
Cc: Rik van Riel <riel@...hat.com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 mm/memory.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3831,7 +3831,7 @@ int generic_access_phys(struct vm_area_s
 	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);
 	else

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