path: root/mm/memory_hotplug.c
diff options
authorAlastair D'Silva <alastair@d-silva.org>2019-11-30 17:53:48 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2019-12-01 12:59:04 -0800
commitdca4436d1cf9e0d237c8ed2af72ed6b78fc7c099 (patch)
tree6462acdf359f7bc2a7f40d476576a2d46c0a89b8 /mm/memory_hotplug.c
parentmm/hotplug: reorder memblock_[free|remove]() calls in try_remove_memory() (diff)
mm/memory_hotplug.c: add a bounds check to __add_pages()
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 Link: http://lkml.kernel.org/r/20191001004617.7536-2-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> Cc: Oscar Salvador <osalvador@suse.de> Cc: Pavel Tatashin <pasha.tatashin@soleen.com> Cc: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to '')
1 files changed, 20 insertions, 0 deletions
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 1b1ad398dff8..8b485900d941 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -278,6 +278,22 @@ 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",
+ (u64)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 +307,10 @@ 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