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>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 23d3339ac4e8e25b7945788014e882fbb0833348..133dad9f466990ad42b3eae669311fc08ecde392 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -8762,7 +8762,8 @@ void *__init alloc_large_system_hash(const char *tablename,
                } 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