arm64: kexec_file: Use struct_size() in kmalloc()

Make use of the struct_size() helper instead of an open-coded version
in order to avoid any potential type mistakes.

This code was detected with the help of Coccinelle and, audited and
fixed manually.

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/20200617213407.GA1385@embeddedor
Signed-off-by: Will Deacon <will@kernel.org>

diff --git a/arch/arm64/kernel/machine_kexec_file.c b/arch/arm64/kernel/machine_kexec_file.c
index 522e6f5..361a114 100644 (file)
--- a/arch/arm64/kernel/machine_kexec_file.c
+++ b/arch/arm64/kernel/machine_kexec_file.c
@@ -219,8 +219,7 @@ static int prepare_elf_headers(void **addr, unsigned long *sz)
                                        MEMBLOCK_NONE, &start, &end, NULL)
                nr_ranges++;
 
-       cmem = kmalloc(sizeof(struct crash_mem) +
-                       sizeof(struct crash_mem_range) * nr_ranges, GFP_KERNEL);
+       cmem = kmalloc(struct_size(cmem, ranges, nr_ranges), GFP_KERNEL);
        if (!cmem)
                return -ENOMEM;