[PATCH] powerpc/kasan: Fix error detection on memory allocation

[Christophe Leroy]

In case (k_start & PAGE_MASK) doesn't equal (kstart), 'va' will never be
NULL allthough 'block' is NULL

Check the return of memblock_alloc() directly instead of
the resulting address in the loop.

Fixes: 509cd3f2b473 ("powerpc/32: Simplify KASAN init")
Signed-off-by: Christophe Leroy <christophe.le...@c-s.fr>
---
 arch/powerpc/mm/kasan/kasan_init_32.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/mm/kasan/kasan_init_32.c 
b/arch/powerpc/mm/kasan/kasan_init_32.c
index b533e7a8319d..e998c3576ae1 100644
--- a/arch/powerpc/mm/kasan/kasan_init_32.c
+++ b/arch/powerpc/mm/kasan/kasan_init_32.c
@@ -78,15 +78,14 @@ static int __init kasan_init_region(void *start, size_t 
size)
                return ret;
 
        block = memblock_alloc(k_end - k_start, PAGE_SIZE);
+       if (!block)
+               return -ENOMEM;
 
        for (k_cur = k_start & PAGE_MASK; k_cur < k_end; k_cur += PAGE_SIZE) {
                pmd_t *pmd = pmd_offset(pud_offset(pgd_offset_k(k_cur), k_cur), 
k_cur);
                void *va = block + k_cur - k_start;
                pte_t pte = pfn_pte(PHYS_PFN(__pa(va)), PAGE_KERNEL);
 
-               if (!va)
-                       return -ENOMEM;
-
                __set_pte_at(&init_mm, k_cur, pte_offset_kernel(pmd, k_cur), 
pte, 0);
        }
        flush_tlb_kernel_range(k_start, k_end);
-- 
2.25.0