linux-kernel - [PATCH v3 2/2] mm: Add a bounds check in devm_memremap

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Message-Id: <20190917010752.28395-3-alastair@au1.ibm.com>
Date:   Tue, 17 Sep 2019 11:07:48 +1000
From:   "Alastair D'Silva" <alastair@....ibm.com>
To:     alastair@...ilva.org
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        David Hildenbrand <david@...hat.com>,
        Oscar Salvador <osalvador@...e.com>,
        Michal Hocko <mhocko@...e.com>,
        Pavel Tatashin <pasha.tatashin@...een.com>,
        Wei Yang <richard.weiyang@...il.com>,
        Dan Williams <dan.j.williams@...el.com>, Qian Cai <cai@....pw>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Logan Gunthorpe <logang@...tatee.com>,
        Ira Weiny <ira.weiny@...el.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v3 2/2] mm: Add a bounds check in devm_memremap_pages()

From: Alastair D'Silva <alastair@...ilva.org>

The call to check_hotplug_memory_addressable() validates that the memory
is fully addressable.

Without this call, it is possible that we may remap pages that is
not physically addressable, resulting in bogus section numbers
being returned from __section_nr().

Signed-off-by: Alastair D'Silva <alastair@...ilva.org>
---
 mm/memremap.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/mm/memremap.c b/mm/memremap.c
index 86432650f829..de2b67586401 100644
--- a/mm/memremap.c
+++ b/mm/memremap.c
@@ -175,6 +175,11 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
 	int error, nid, is_ram;
 	bool need_devmap_managed = true;
 
+	error = check_hotplug_memory_addressable(res->start,
+						 resource_size(res));
+	if (error)
+		return ERR_PTR(error);
+
 	switch (pgmap->type) {
 	case MEMORY_DEVICE_PRIVATE:
 		if (!IS_ENABLED(CONFIG_DEVICE_PRIVATE)) {
-- 
2.21.0