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From: "Alastair D'Silva" <alastair@au1.ibm.com>
To: alastair@d-silva.org
Cc: "Benjamin Herrenschmidt" <benh@kernel.crashing.org>,
	"Paul Mackerras" <paulus@samba.org>,
	"Michael Ellerman" <mpe@ellerman.id.au>,
	"Frederic Barrat" <fbarrat@linux.ibm.com>,
	"Andrew Donnellan" <ajd@linux.ibm.com>,
	"Arnd Bergmann" <arnd@arndb.de>,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"Mauro Carvalho Chehab" <mchehab+samsung@kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	"Rob Herring" <robh@kernel.org>,
	"Anton Blanchard" <anton@ozlabs.org>,
	"Krzysztof Kozlowski" <krzk@kernel.org>,
	"Mahesh Salgaonkar" <mahesh@linux.vnet.ibm.com>,
	"Madhavan Srinivasan" <maddy@linux.vnet.ibm.com>,
	"Cédric Le Goater" <clg@kaod.org>,
	"Anju T Sudhakar" <anju@linux.vnet.ibm.com>,
	"Hari Bathini" <hbathini@linux.ibm.com>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Greg Kurz" <groug@kaod.org>,
	"Nicholas Piggin" <npiggin@gmail.com>,
	"Masahiro Yamada" <yamada.masahiro@socionext.com>,
	"Alexey Kardashevskiy" <aik@ozlabs.ru>,
	linux-kernel@vger.kernel.org, linuxppc-dev@list
Subject: [PATCH v2 01/27] memory_hotplug: Add a bounds check to __add_pages
Date: Tue,  3 Dec 2019 14:46:29 +1100
Message-ID: <20191203034655.51561-2-alastair@au1.ibm.com> (raw)
In-Reply-To: <20191203034655.51561-1-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 f307bd82d750..b5be827ecda5 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
-- 
2.23.0
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Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-03  3:46 [PATCH v2 00/27] Add support for OpenCAPI SCM devices Alastair D'Silva
2019-12-03  3:46 ` Alastair D'Silva [this message]
2019-12-03  3:46 ` [PATCH v2 02/27] nvdimm: remove prototypes for nonexistent functions Alastair D'Silva
2019-12-03  4:47   ` Andrew Donnellan
2019-12-04  0:10   ` Dan Williams
2019-12-03  3:46 ` [PATCH v2 03/27] powerpc: Add OPAL calls for LPC memory alloc/release Alastair D'Silva
2019-12-03  3:46 ` [PATCH v2 04/27] mm/memory_hotplug: Allow check_hotplug_memory_addressable to be called from drivers Alastair D'Silva
2019-12-03  3:46 ` [PATCH v2 05/27] powerpc: Map & release OpenCAPI LPC memory Alastair D'Silva
2020-01-09 14:41   ` Frederic Barrat
2019-12-03  3:46 ` [PATCH v2 06/27] ocxl: Tally up the LPC memory on a link & allow it to be mapped Alastair D'Silva
2020-01-09 14:48   ` Frederic Barrat
2019-12-03  3:46 ` [PATCH v2 07/27] ocxl: Add functions to map/unmap LPC memory Alastair D'Silva
2020-01-09 14:49   ` Frederic Barrat
2019-12-03  3:46 ` [PATCH v2 08/27] ocxl: Save the device serial number in ocxl_fn Alastair D'Silva
2019-12-03  3:46 ` [PATCH v2 09/27] ocxl: Free detached contexts in ocxl_context_detach_all() Alastair D'Silva
2020-01-09 14:54   ` Frederic Barrat
2019-12-03  3:46 ` [PATCH v2 10/27] nvdimm: Add driver for OpenCAPI Storage Class Memory Alastair D'Silva
2019-12-03  5:05   ` Alastair D'Silva
2019-12-03  3:46 ` [PATCH v2 11/27] nvdimm/ocxl: Add register addresses & status values to header Alastair D'Silva
2019-12-03  3:46 ` [PATCH v2 12/27] nvdimm/ocxl: Read the capability registers & wait for device ready Alastair D'Silva
2019-12-03  3:46 ` [PATCH v2 13/27] nvdimm/ocxl: Add support for Admin commands Alastair D'Silva
2019-12-03  3:46 ` [PATCH v2 14/27] nvdimm/ocxl: Add support for near storage commands Alastair D'Silva
2019-12-03  3:46 ` [PATCH v2 15/27] nvdimm/ocxl: Register a character device for userspace to interact with Alastair D'Silva
2019-12-03  3:46 ` [PATCH v2 16/27] nvdimm/ocxl: Implement the Read Error Log command Alastair D'Silva
2019-12-05  3:42   ` Alastair D'Silva
2019-12-05 19:34   ` kbuild test robot
2019-12-03  3:46 ` [PATCH v2 17/27] nvdimm/ocxl: Add controller dump IOCTLs Alastair D'Silva
2019-12-03  3:46 ` [PATCH v2 18/27] nvdimm/ocxl: Add an IOCTL to report controller statistics Alastair D'Silva
2019-12-03  3:46 ` [PATCH v2 19/27] nvdimm/ocxl: Forward events to userspace Alastair D'Silva
2019-12-03  3:46 ` [PATCH v2 20/27] nvdimm/ocxl: Add an IOCTL to request controller health & perf data Alastair D'Silva
2019-12-03  3:46 ` [PATCH v2 21/27] nvdimm/ocxl: Support firmware update via sysfs Alastair D'Silva
2019-12-03  3:46 ` [PATCH v2 22/27] nvdimm/ocxl: Implement the heartbeat command Alastair D'Silva
2019-12-03  3:46 ` [PATCH v2 23/27] nvdimm/ocxl: Add debug IOCTLs Alastair D'Silva
2019-12-03  3:46 ` [PATCH v2 24/27] nvdimm/ocxl: Implement Overwrite Alastair D'Silva
2019-12-03  3:46 ` [PATCH v2 25/27] nvdimm/ocxl: Expose SMART data via ndctl Alastair D'Silva
2019-12-16  0:15   ` Alastair D'Silva
2019-12-03  3:46 ` [PATCH v2 26/27] powerpc: Enable OpenCAPI Storage Class Memory driver on bare metal Alastair D'Silva
2019-12-03  4:54   ` Andrew Donnellan
2019-12-03  4:57     ` Alastair D'Silva
2019-12-03  3:46 ` [PATCH v2 27/27] MAINTAINERS: Add myself & nvdimm/ocxl to ocxl Alastair D'Silva
2019-12-03  3:50 ` [PATCH v2 00/27] Add support for OpenCAPI SCM devices Matthew Wilcox
2019-12-03  4:01   ` Alastair D'Silva
2019-12-03 12:42     ` Matthew Wilcox
2019-12-04  0:15       ` Dan Williams

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