linux-kernel - [PATCH v3 2/8] mm, devm_memremap_pages: Kill mapping "System RAM" support

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Mon, 18 Jun 2018 23:04:49 -0700
From:   Dan Williams <dan.j.williams@...el.com>
To:     akpm@...ux-foundation.org
Cc:     Christoph Hellwig <hch@....de>,
        Jérôme Glisse <jglisse@...hat.com>,
        Logan Gunthorpe <logang@...tatee.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v3 2/8] mm,
 devm_memremap_pages: Kill mapping "System RAM" support

Given the fact that devm_memremap_pages() requires a percpu_ref that is
torn down by devm_memremap_pages_release() the current support for
mapping RAM is broken.

This has been broken since forever and there is no use case to map RAM
in this way, so just kill the support and make it an explicit error.

Cc: Christoph Hellwig <hch@....de>
Cc: "Jérôme Glisse" <jglisse@...hat.com>
Cc: Logan Gunthorpe <logang@...tatee.com>
Signed-off-by: Dan Williams <dan.j.williams@...el.com>
---
 kernel/memremap.c |    9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/kernel/memremap.c b/kernel/memremap.c
index 4478e4688bb7..2d2c901cbe23 100644
--- a/kernel/memremap.c
+++ b/kernel/memremap.c
@@ -183,15 +183,12 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
 	is_ram = region_intersects(align_start, align_size,
 		IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE);
 
-	if (is_ram == REGION_MIXED) {
-		WARN_ONCE(1, "%s attempted on mixed region %pr\n",
-				__func__, res);
+	if (is_ram != REGION_DISJOINT) {
+		WARN_ONCE(1, "%s attempted on %s region %pr\n", __func__,
+				is_ram == REGION_MIXED ? "mixed" : "ram", res);
 		return ERR_PTR(-ENXIO);
 	}
 
-	if (is_ram == REGION_INTERSECTS)
-		return __va(res->start);
-
 	if (!pgmap->ref)
 		return ERR_PTR(-EINVAL);