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From: "Alastair D'Silva" <alastair@au1.ibm.com>
To: alastair@d-silva.org
Cc: "Oscar Salvador" <osalvador@suse.com>,
	"Michal Hocko" <mhocko@suse.com>,
	"Geert Uytterhoeven" <geert+renesas@glider.be>,
	"David Hildenbrand" <david@redhat.com>,
	"Alexey Kardashevskiy" <aik@ozlabs.ru>,
	"Wei Yang" <richard.weiyang@gmail.com>,
	"Keith Busch" <keith.busch@intel.com>,
	"Masahiro Yamada" <yamada.masahiro@socionext.com>,
	"Paul Mackerras" <paulus@samba.org>,
	"Ira Weiny" <ira.weiny@intel.com>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Pavel Tatashin" <pasha.tatashin@soleen.com>,
	"Dave Jiang" <dave.jiang@intel.com>,
	linux-nvdimm@lists.01.org,
	"Vishal Verma" <vishal.l.verma@intel.com>,
	"Krzysztof Kozlowski" <krzk@kernel.org>,
	"Mahesh Salgaonkar" <mahesh@linux.vnet.ibm.com>,
	"Andrew Donnellan" <ajd@linux.ibm.com>,
	"Arnd Bergmann" <arnd@arndb.de>, "Greg Kurz" <groug@kaod.org>,
	"Nicholas Piggin" <npiggin@gmail.com>, "Qian Cai" <cai@lca.pw>,
	"Cédric Le Goater" <clg@kaod.org>,
	"Dan Williams" <dan.j.williams@intel.com>,
	"Hari Bathini" <hbathini@linux.ibm.com>,
	"David Gibson" <david@gibson.dropbear.id.au>,
	linux-mm@kvack.org,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	linux-kernel@vger.kernel.org,
	"Vasant Hegde" <hegdevasant@linux.vnet.ibm.com>,
	"Frederic Barrat" <fbarrat@linux.ibm.com>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	linuxppc-dev@lists.ozlabs.org
Subject: [PATCH 01/10] memory_hotplug: Add a bounds check to __add_pages
Date: Fri, 25 Oct 2019 15:46:56 +1100
Message-ID: <20191025044721.16617-2-alastair@au1.ibm.com> (raw)
In-Reply-To: <20191025044721.16617-1-alastair@au1.ibm.com>

From: Alastair D'Silva <alastair@d-silva.org>

On PowerPC, the address ranges allocated to OpenCAPI LPC memory
are allocated from firmware. These address ranges may be higher
than what older kernels permit, as we increased the maximum
permissable address in commit 4ffe713b7587
("powerpc/mm: Increase the max addressable memory to 2PB"). It is
possible that the addressable range may change again in the
future.

In this scenario, we end up with a bogus section returned from
__section_nr (see the discussion on the thread "mm: Trigger bug on
if a section is not found in __section_nr").

Adding a check here means that we fail early and have an
opportunity to handle the error gracefully, rather than rumbling
on and potentially accessing an incorrect section.

Further discussion is also on the thread ("powerpc: Perform a bounds
check in arch_add_memory")
http://lkml.kernel.org/r/20190827052047.31547-1-alastair@au1.ibm.com

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
---
 mm/memory_hotplug.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index df570e5c71cc..2cecf07b396f 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -278,6 +278,23 @@ static int check_pfn_span(unsigned long pfn, unsigned long nr_pages,
 	return 0;
 }
 
+static int check_hotplug_memory_addressable(unsigned long pfn,
+					    unsigned long nr_pages)
+{
+	const u64 max_addr = PFN_PHYS(pfn + nr_pages) - 1;
+
+	if (max_addr >> MAX_PHYSMEM_BITS) {
+		const u64 max_allowed = (1ull << (MAX_PHYSMEM_BITS + 1)) - 1;
+
+		WARN(1,
+		     "Hotplugged memory exceeds maximum addressable address, range=%#llx-%#llx, maximum=%#llx\n",
+		     PFN_PHYS(pfn), max_addr, max_allowed);
+		return -E2BIG;
+	}
+
+	return 0;
+}
+
 /*
  * Reasonably generic function for adding memory.  It is
  * expected that archs that support memory hotplug will
@@ -291,6 +308,10 @@ int __ref __add_pages(int nid, unsigned long pfn, unsigned long nr_pages,
 	unsigned long nr, start_sec, end_sec;
 	struct vmem_altmap *altmap = restrictions->altmap;
 
+	err = check_hotplug_memory_addressable(pfn, nr_pages);
+	if (err)
+		return err;
+
 	if (altmap) {
 		/*
 		 * Validate altmap is within bounds of the total request
-- 
2.21.0


  reply index

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-25  4:46 [PATCH 00/10] Add support for OpenCAPI SCM devices Alastair D'Silva
2019-10-25  4:46 ` Alastair D'Silva [this message]
2019-10-25  4:46 ` [PATCH 02/10] nvdimm: remove prototypes for nonexistent functions Alastair D'Silva
2019-10-27 23:41   ` Andrew Donnellan
2019-11-07 17:56   ` Frederic Barrat
2019-11-15  4:30   ` Dan Williams
2019-10-25  4:46 ` [PATCH 03/10] powerpc: Add OPAL calls for LPC memory alloc/release Alastair D'Silva
2019-11-07 17:57   ` Frederic Barrat
2019-10-25  4:46 ` [PATCH 04/10] powerpc: Map & release OpenCAPI LPC memory Alastair D'Silva
2019-10-27 21:24   ` kbuild test robot
2019-10-27 21:59   ` kbuild test robot
2019-10-28  2:34   ` kbuild test robot
2019-10-29  1:49   ` Andrew Donnellan
2019-10-29  2:44     ` Alastair D'Silva
2019-10-29  2:47       ` Andrew Donnellan
2019-11-07 17:59   ` Frederic Barrat
2019-11-11  9:34   ` Aneesh Kumar K.V
2019-10-25  4:47 ` [PATCH 05/10] ocxl: Tally up the LPC memory on a link & allow it to be mapped Alastair D'Silva
2019-11-07 18:02   ` Frederic Barrat
2019-10-25  4:47 ` [PATCH 06/10] ocxl: Add functions to map/unmap LPC memory Alastair D'Silva
2019-11-07 18:05   ` Frederic Barrat
2019-10-25  4:47 ` [PATCH 07/10] ocxl: Save the device serial number in ocxl_fn Alastair D'Silva
2019-11-06  3:10   ` Andrew Donnellan
2019-11-07 18:18   ` Frederic Barrat
2019-10-25  4:47 ` [PATCH 08/10] nvdimm: Add driver for OpenCAPI Storage Class Memory Alastair D'Silva
2019-10-27 22:19   ` kbuild test robot
2019-10-27 22:53   ` kbuild test robot
2019-10-28  1:12   ` [RFC PATCH] nvdimm: scm_get() can be static kbuild test robot
2019-11-11 11:14   ` [PATCH 08/10] nvdimm: Add driver for OpenCAPI Storage Class Memory Aneesh Kumar K.V
2019-11-12  5:37     ` Dan Williams
2019-11-12  5:41       ` Dan Williams
2019-11-14 13:41   ` Frederic Barrat
2019-11-14 16:35     ` Dan Williams
2019-11-18 23:47       ` Andrew Donnellan
2019-11-19  0:04         ` Dan Williams
2019-11-19  2:48         ` Alastair D'Silva
2019-11-19  3:26           ` Andrew Donnellan
2019-11-19  4:41             ` Dan Williams
2019-11-18 23:01     ` Alastair D'Silva
2019-10-25  4:47 ` [PATCH 09/10] powerpc: Enable OpenCAPI Storage Class Memory driver on bare metal Alastair D'Silva
2019-10-28  2:43   ` Oliver O'Halloran
2019-11-08  7:10   ` Frederic Barrat
2019-11-11  9:46   ` Aneesh Kumar K.V
2019-10-25  4:47 ` [PATCH 10/10] ocxl: Conditionally bind SCM devices to the generic OCXL driver Alastair D'Silva
2019-10-26  6:43   ` Christoph Hellwig
2019-11-06  3:46   ` Andrew Donnellan
2019-11-07 18:08   ` Frederic Barrat
2019-11-08  0:37     ` Alastair D'Silva
2019-10-25  7:57 ` [PATCH 00/10] Add support for OpenCAPI SCM devices Geert Uytterhoeven

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