linux-kernel - [PATCH v4 01/45] powerpc/kasan: Fix error detection on memory allocation

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Message-Id: <7cb8ca82042bfc45a5cfe726c921cd7e7eeb12a3.1589866984.git.christophe.leroy@csgroup.eu>
Date:   Tue, 19 May 2020 05:48:43 +0000 (UTC)
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH v4 01/45] powerpc/kasan: Fix error detection on memory
 allocation

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.leroy@...roup.eu>
---
 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 cbcad369fcb2..8b15fe09b967 100644
--- a/arch/powerpc/mm/kasan/kasan_init_32.c
+++ b/arch/powerpc/mm/kasan/kasan_init_32.c
@@ -76,15 +76,14 @@ 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_ptr_k(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