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Miller" , Rob Herring , Anton Blanchard , Krzysztof Kozlowski , Mahesh Salgaonkar , Madhavan Srinivasan , =?UTF-8?q?C=C3=A9dric=20Le=20Goater?= , Anju T Sudhakar , Hari Bathini , Thomas Gleixner , Greg Kurz , Nicholas Piggin , Masahiro Yamada , Alexey Kardashevskiy , linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-nvdimm@lists.01.org, linux-mm@kvack.org, David Hildenbrand , Michal Hocko Subject: [PATCH v2 01/27] memory_hotplug: Add a bounds check to __add_pages Date: Tue, 3 Dec 2019 14:46:29 +1100 X-Mailer: git-send-email 2.23.0 In-Reply-To: <20191203034655.51561-1-alastair@au1.ibm.com> References: <20191203034655.51561-1-alastair@au1.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 19120303-0028-0000-0000-000003C3CC72 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19120303-0029-0000-0000-00002486E431 Message-Id: <20191203034655.51561-2-alastair@au1.ibm.com> X-Proofpoint-UnRewURL: 0 URL was un-rewritten MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.95,18.0.572 definitions=2019-12-02_06:2019-11-29,2019-12-02 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 clxscore=1015 priorityscore=1501 impostorscore=0 adultscore=0 phishscore=0 bulkscore=0 suspectscore=1 lowpriorityscore=0 mlxlogscore=999 mlxscore=0 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-1910280000 definitions=main-1912030032 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Alastair D'Silva 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 Reviewed-by: David Hildenbrand Acked-by: Michal Hocko --- 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, unsigne= d long nr_pages, return 0; } =20 +static int check_hotplug_memory_addressable(unsigned long pfn, + unsigned long nr_pages) +{ + const u64 max_addr =3D PFN_PHYS(pfn + nr_pages) - 1; + + if (max_addr >> MAX_PHYSMEM_BITS) { + const u64 max_allowed =3D (1ull << (MAX_PHYSMEM_BITS + 1)) - 1; + + WARN(1, + "Hotplugged memory exceeds maximum addressable address, range=3D%= #llx-%#llx, maximum=3D%#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, un= signed long nr_pages, unsigned long nr, start_sec, end_sec; struct vmem_altmap *altmap =3D restrictions->altmap; =20 + err =3D check_hotplug_memory_addressable(pfn, nr_pages); + if (err) + return err; + if (altmap) { /* * Validate altmap is within bounds of the total request --=20 2.23.0