linux-kernel - [PATCH 5.4 27/54] powerpc/64s/powernv: Fix memory corruption when saving SLB entries on MCE

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Date:   Thu, 10 Dec 2020 15:27:04 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Nicholas Piggin <npiggin@...il.com>,
        Mahesh Salgaonkar <mahesh@...ux.ibm.com>,
        Michael Ellerman <mpe@...erman.id.au>
Subject: [PATCH 5.4 27/54] powerpc/64s/powernv: Fix memory corruption when saving SLB entries on MCE

From: Nicholas Piggin <npiggin@...il.com>

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@...r.kernel.org # v5.4+
Signed-off-by: Nicholas Piggin <npiggin@...il.com>
Acked-by: Mahesh Salgaonkar <mahesh@...ux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
Link: https://lore.kernel.org/r/20201128070728.825934-2-npiggin@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/powerpc/platforms/powernv/setup.c |    9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

--- 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));
+		}
 	}
 }