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[PATCH] ppc/spapr: Fix ubsan warning with unaligned pointer access


From: Daniel Hoffman
Subject: [PATCH] ppc/spapr: Fix ubsan warning with unaligned pointer access
Date: Sat, 16 Dec 2023 16:14:40 -0800

Found while running QTest with UBsan. Unaligned pointers appear to be
valid, so moving the read to an explicit memcpy to an intermediate.
---
 hw/ppc/vof.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/hw/ppc/vof.c b/hw/ppc/vof.c
index e3b430a81f4..609a51c645d 100644
--- a/hw/ppc/vof.c
+++ b/hw/ppc/vof.c
@@ -646,7 +646,10 @@ static void vof_dt_memory_available(void *fdt, GArray 
*claimed, uint64_t base)
     mem0_reg = fdt_getprop(fdt, offset, "reg", &proplen);
     g_assert(mem0_reg && proplen == sizeof(uint32_t) * (ac + sc));
     if (sc == 2) {
-        mem0_end = be64_to_cpu(*(uint64_t *)(mem0_reg + sizeof(uint32_t) * 
ac));
+        /* Pointer may be unaligned */
+        uint64_t mem0_end_copy;
+        memcpy(&mem0_end_copy, mem0_reg + sizeof(uint32_t) * ac, 
sizeof(mem0_end_copy));
+        mem0_end = be64_to_cpu(mem0_end_copy);
     } else {
         mem0_end = be32_to_cpu(*(uint32_t *)(mem0_reg + sizeof(uint32_t) * 
ac));
     }
-- 
2.40.1




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