[PATCH] powerpc: Perform a bounds check in arch_add_memory

[Alastair D'Silva]

From: Alastair D'Silva <alastair@xxxxxxxxxxx>

It is possible for firmware to allocate memory ranges outside
the range of physical memory that we support (MAX_PHYSMEM_BITS).

This patch adds a bounds check to ensure that any hotplugged
memory is addressable.

Signed-off-by: Alastair D'Silva <alastair@xxxxxxxxxxx>
---
 arch/powerpc/mm/mem.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index 9191a66b3bc5..de18fb73de30 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -111,6 +111,9 @@ int __ref arch_add_memory(int nid, u64 start, u64 size,
 	unsigned long nr_pages = size >> PAGE_SHIFT;
 	int rc;
 
+	if ((start + size - 1) >> MAX_PHYSMEM_BITS)
+		return -EINVAL;
+
 	resize_hpt_for_hotplug(memblock_phys_mem_size());
 
 	start = (unsigned long)__va(start);
-- 
2.21.0