From: Grazvydas Ignotas <notasas@gmail.com>
Date: Thu, 12 Feb 2015 23:00:19 +0000 (-0800)
Subject: mm/memory.c: actually remap enough memory
X-Git-Tag: v3.12.39~80
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=970970dcb4fca4fdcbb1b9bf4d7cd686796dc9d6;p=thirdparty%2Fkernel%2Fstable.git

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@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---

diff --git a/mm/memory.c b/mm/memory.c
index db2916f5f378f..cf05415c25a6b 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4079,7 +4079,7 @@ 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);
 	else