From af669a0b2d165d2a88bff0f66776327b00e7ed98 Mon Sep 17 00:00:00 2001
From: "jie@chenjie6@huwei.com" <jie@chenjie6@huwei.com>
Date: Fri, 10 Aug 2018 17:23:06 -0700
Subject: [PATCH] mm/memory.c: check return value of ioremap_prot

[ Upstream commit 24eee1e4c47977bdfb71d6f15f6011e7b6188d04 ]

ioremap_prot() can return NULL which could lead to an oops.

Link: http://lkml.kernel.org/r/1533195441-58594-1-git-send-email-chenjie6@huawei.com
Signed-off-by: chen jie <chenjie6@huawei.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Li Zefan <lizefan@huawei.com>
Cc: chenjie <chenjie6@huawei.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 mm/memory.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/mm/memory.c b/mm/memory.c
index 88f8d6a2af05..0ff735601654 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3861,6 +3861,9 @@ int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
 		return -EINVAL;
 
 	maddr = ioremap_prot(phys_addr, PAGE_ALIGN(len + offset), prot);
+	if (!maddr)
+		return -ENOMEM;
+
 	if (write)
 		memcpy_toio(maddr + offset, buf, len);
 	else
-- 
2.20.1