[patch 102/262] mm/large system hash: avoid possible NULL deref in alloc_large_system_hash

Andrew Morton
2021-11-05T20:40:03Z

From: Eric Dumazet <edumazet@google.com>
Subject: mm/large system hash: avoid possible NULL deref in alloc_large_system_hash

If __vmalloc() returned NULL, is_vm_area_hugepages(NULL) will fault if
CONFIG_HAVE_ARCH_HUGE_VMALLOC=y

Link: https://lkml.kernel.org/r/20210915212530.2321545-1-eric.dumazet@gmail.com
Fixes: 121e6f3258fe ("mm/vmalloc: hugepage vmalloc mappings")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

mm/page_alloc.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/mm/page_alloc.c~mm-large-system-hash-avoid-possible-null-deref-in-alloc_large_system_hash
+++ a/mm/page_alloc.c
@@ -8762,7 +8762,8 @@ void *__init alloc_large_system_hash(con
} else if (get_order(size) >= MAX_ORDER || hashdist) {
table = __vmalloc(size, gfp_flags);
virt = true;
- huge = is_vm_area_hugepages(table);
+ if (table)
+ huge = is_vm_area_hugepages(table);
} else {
/*
* If bucketsize is not a power-of-two, we may free
_