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

Commit Message

Andrew Morton Nov. 5, 2021, 8:39 p.m. UTC

From: Eric Dumazet <[e-mail]>
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/[e-mail]
Fixes: 121e6f3258fe ("mm/vmalloc: hugepage vmalloc mappings")
Signed-off-by: Eric Dumazet <[e-mail]>
Reviewed-by: Andrew Morton <[e-mail]>
Cc: Nicholas Piggin <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

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

Patch

--- 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