btrfs: use kvcalloc for allocation in btrfs_ioctl_send()

Replace kvzalloc() call with kvcalloc() that also checks the size
internally. There's a standalone overflow check in the function so we
can return invalid parameter combination.  Use array_size() helper to
compute the memory size for clone_sources_tmp.

Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Denis Efremov <efremov@linux.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
index 79b7d15ca50f4ed2a4d5e8f0c7844f539cd75257..b84f921ed6c0d71aa9be14342afdf9eeb09111dc 100644 (file)
--- a/fs/btrfs/send.c
+++ b/fs/btrfs/send.c
@@ -7061,7 +7061,7 @@ long btrfs_ioctl_send(struct file *mnt_file, struct btrfs_ioctl_send_args *arg)
        u32 i;
        u64 *clone_sources_tmp = NULL;
        int clone_sources_to_rollback = 0;
-       unsigned alloc_size;
+       size_t alloc_size;
        int sort_clone_roots = 0;
 
        if (!capable(CAP_SYS_ADMIN))
@@ -7147,15 +7147,16 @@ long btrfs_ioctl_send(struct file *mnt_file, struct btrfs_ioctl_send_args *arg)
        sctx->waiting_dir_moves = RB_ROOT;
        sctx->orphan_dirs = RB_ROOT;
 
-       alloc_size = sizeof(struct clone_root) * (arg->clone_sources_count + 1);
-
-       sctx->clone_roots = kvzalloc(alloc_size, GFP_KERNEL);
+       sctx->clone_roots = kvcalloc(sizeof(*sctx->clone_roots),
+                                    arg->clone_sources_count + 1,
+                                    GFP_KERNEL);
        if (!sctx->clone_roots) {
                ret = -ENOMEM;
                goto out;
        }
 
-       alloc_size = arg->clone_sources_count * sizeof(*arg->clone_sources);
+       alloc_size = array_size(sizeof(*arg->clone_sources),
+                               arg->clone_sources_count);
 
        if (arg->clone_sources_count) {
                clone_sources_tmp = kvmalloc(alloc_size, GFP_KERNEL);