selftests/mm: use calloc instead of malloc in pagemap_ioctl.c

As per Documentation/process/deprecated.rst, dynamic size calculations
should not be performed in memory allocator arguments due to possible
overflows.

Replace malloc with calloc to avoid open-ended arithmetic and prevent
possible overflows.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: I Viswanath <[e-mail]>
Reviewed-by: Vishal Moola (Oracle) <[e-mail]>
Acked-by: David Hildenbrand <[e-mail]>
Reviewed by: Donet Tom <[e-mail]>
Cc: Liam Howlett <[e-mail]>
Cc: Lorenzo Stoakes <[e-mail]>
Cc: Michal Hocko <[e-mail]>
Cc: Mike Rapoport <[e-mail]>
Cc: Shuah Khan <[e-mail]>
Cc: Suren Baghdasaryan <[e-mail]>
Cc: Vlastimil Babka <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

tools/testing/selftests/mm/pagemap_ioctl.c

···
 	wp_addr_range(mem, mem_size);
 
 	vec_size = mem_size/page_size;
-	vec = malloc(sizeof(struct page_region) * vec_size);
+	vec = calloc(vec_size, sizeof(struct page_region));
 
 	written = pagemap_ioctl(mem, mem_size, vec, 1, PM_SCAN_WP_MATCHING | PM_SCAN_CHECK_WPASYNC,
 				vec_size - 2, PAGE_IS_WRITTEN, 0, 0, PAGE_IS_WRITTEN);
···
 	vec_size = num_pages/2;
 	mem_size = num_pages * page_size;
 
-	vec = malloc(sizeof(struct page_region) * vec_size);
+	vec = calloc(vec_size, sizeof(struct page_region));
 	if (!vec)
 		ksft_exit_fail_msg("error nomem\n");
 
-	vec2 = malloc(sizeof(struct page_region) * vec_size);
+	vec2 = calloc(vec_size, sizeof(struct page_region));
 	if (!vec2)
 		ksft_exit_fail_msg("error nomem\n");
 
···
 	mem_size = 1050 * page_size;
 	vec_size = mem_size/(page_size*2);
 
-	vec = malloc(sizeof(struct page_region) * vec_size);
+	vec = calloc(vec_size, sizeof(struct page_region));
 	if (!vec)
 		ksft_exit_fail_msg("error nomem\n");
 
···
 	mem_size = 10000 * page_size;
 	vec_size = 50;
 
-	vec = malloc(sizeof(struct page_region) * vec_size);
+	vec = calloc(vec_size, sizeof(struct page_region));
 	if (!vec)
 		ksft_exit_fail_msg("error nomem\n");
 
···
 	vec_size = 1000;
 	mem_size = vec_size * page_size;
 
-	vec = malloc(sizeof(struct page_region) * vec_size);
+	vec = calloc(vec_size, sizeof(struct page_region));
 	if (!vec)
 		ksft_exit_fail_msg("error nomem\n");
 
···
 	}
 
 	vec_size = mem_size/page_size;
-	vec = malloc(sizeof(struct page_region) * vec_size);
-	vec2 = malloc(sizeof(struct page_region) * vec_size);
+	vec = calloc(vec_size, sizeof(struct page_region));
+	vec2 = calloc(vec_size, sizeof(struct page_region));
 
 	/* 1. all new pages must be not be written (dirty) */
 	written = pagemap_ioctl(mem, mem_size, vec, 1, PM_SCAN_WP_MATCHING | PM_SCAN_CHECK_WPASYNC,
···
 	unsigned long long vec_size = map_size/page_size;
 	struct page_region *vec, *vec2;
 
-	vec = malloc(sizeof(struct page_region) * vec_size);
-	vec2 = malloc(sizeof(struct page_region) * vec_size);
+	vec = calloc(vec_size, sizeof(struct page_region));
+	vec2 = calloc(vec_size, sizeof(struct page_region));
 	if (!vec || !vec2)
 		ksft_exit_fail_msg("malloc failed\n");
 
···
 	void *start = (void *)0x10000000;
 	int written, len = 0x00040000;
 	long vec_size = len / page_size;
-	struct page_region *vec = malloc(sizeof(struct page_region) * vec_size);
+	struct page_region *vec = calloc(vec_size, sizeof(struct page_region));
 
 	/* 1. Get written pages */
 	written = pagemap_ioctl(start, len, vec, vec_size, 0, 0,
···
 	mem_size = 10 * page_size;
 	vec_size = mem_size / page_size;
 
-	vec = malloc(sizeof(struct page_region) * vec_size);
+	vec = calloc(vec_size, sizeof(struct page_region));
 	mem = mmap(NULL, mem_size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON, -1, 0);
 	if (mem == MAP_FAILED || vec == MAP_FAILED)
 		ksft_exit_fail_msg("error nomem\n");