ext4: use kmemdup() to replace kmalloc + memcpy

Replace kmalloc + memcpy with kmemdup()
Signed-off-by: Shuqi Zhang <zhangshuqi3@huawei.com>
Reviewed-by: Ritesh Harjani <ritesh.list@gmail.com>
Link: https://lore.kernel.org/r/20220525030120.803330-1-zhangshuqi3@huawei.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/xattr.c

@@ -1895,11 +1895,10 @@ ext4_xattr_block_set(handle_t *handle, struct inode *inode,
 
 			unlock_buffer(bs->bh);
 			ea_bdebug(bs->bh, "cloning");
-			s->base = kmalloc(bs->bh->b_size, GFP_NOFS);
+			s->base = kmemdup(BHDR(bs->bh), bs->bh->b_size, GFP_NOFS);
 			error = -ENOMEM;
 			if (s->base == NULL)
 				goto cleanup;
-			memcpy(s->base, BHDR(bs->bh), bs->bh->b_size);
 			s->first = ENTRY(header(s->base)+1);
 			header(s->base)->h_refcount = cpu_to_le32(1);
 			s->here = ENTRY(s->base + offset);