powerpc/64s/powernv: Fix memory corruption when saving SLB entries on MCE

commit a1ee28117077c3bf24e5ab6324c835eaab629c45 upstream.

This can be hit by an HPT guest running on an HPT host and bring down
the host, so it's quite important to fix.

Fixes: 7290f3b3d3e6 ("powerpc/64s/powernv: machine check dump SLB contents")
Cc: stable@vger.kernel.org # v5.4+
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Acked-by: Mahesh Salgaonkar <mahesh@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201128070728.825934-2-npiggin@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/powerpc/platforms/powernv/setup.c b/arch/powerpc/platforms/powernv/setup.c
index 0b4f72e002c2e7140e2ff21060d6e73084676196..47eb218a4ae0b21ef6bc04dff473bf992c9033eb 100644 (file)
--- a/arch/powerpc/platforms/powernv/setup.c
+++ b/arch/powerpc/platforms/powernv/setup.c
@@ -186,11 +186,16 @@ static void __init pnv_init(void)
                add_preferred_console("hvc", 0, NULL);
 
        if (!radix_enabled()) {
+               size_t size = sizeof(struct slb_entry) * mmu_slb_size;
                int i;
 
                /* Allocate per cpu area to save old slb contents during MCE */
-               for_each_possible_cpu(i)
-                       paca_ptrs[i]->mce_faulty_slbs = memblock_alloc_node(mmu_slb_size, __alignof__(*paca_ptrs[i]->mce_faulty_slbs), cpu_to_node(i));
+               for_each_possible_cpu(i) {
+                       paca_ptrs[i]->mce_faulty_slbs =
+                                       memblock_alloc_node(size,
+                                               __alignof__(struct slb_entry),
+                                               cpu_to_node(i));
+               }
        }
 }