Btrfs: fix an integer overflow check

[mirror_ubuntu-artful-kernel.git] / fs / btrfs / send.c

diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
index 456c8901489b6c6b468901854bcdcbc53cb5cf13..a60d5bfb8a49e2bfc3faef10f4ea353a9da5f8b8 100644 (file)
--- a/fs/btrfs/send.c
+++ b/fs/btrfs/send.c
@@ -6305,8 +6305,13 @@ long btrfs_ioctl_send(struct file *mnt_file, void __user *arg_)
                goto out;
        }
 
+       /*
+        * Check that we don't overflow at later allocations, we request
+        * clone_sources_count + 1 items, and compare to unsigned long inside
+        * access_ok.
+        */
        if (arg->clone_sources_count >
-           ULLONG_MAX / sizeof(*arg->clone_sources)) {
+           ULONG_MAX / sizeof(struct clone_root) - 1) {
                ret = -EINVAL;
                goto out;
        }