btrfs: return EINVAL if start > total_bytes in fitrim ioctl

We should retirn EINVAL if the start is beyond the end of the file
system in the btrfs_ioctl_fitrim(). Fix that by adding the appropriate
check for it.

Also in the btrfs_trim_fs() it is possible that len+start might overflow
if big values are passed. Fix it by decrementing the len so that start+len
is equal to the file system size in the worst case.

Signed-off-by: Lukas Czerner <lczerner@redhat.com>

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index d524b66..136a2f9 100644 (file)
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -282,6 +282,7 @@ static noinline int btrfs_ioctl_fitrim(struct file *file, void __user *arg)
        struct fstrim_range range;
        u64 minlen = ULLONG_MAX;
        u64 num_devices = 0;
+       u64 total_bytes = btrfs_super_total_bytes(&root->fs_info->super_copy);
        int ret;
 
        if (!capable(CAP_SYS_ADMIN))
@@ -300,12 +301,15 @@ static noinline int btrfs_ioctl_fitrim(struct file *file, void __user *arg)
                }
        }
        rcu_read_unlock();
+
        if (!num_devices)
                return -EOPNOTSUPP;
-
        if (copy_from_user(&range, arg, sizeof(range)))
                return -EFAULT;
+       if (range.start > total_bytes)
+               return -EINVAL;
 
+       range.len = min(range.len, total_bytes - range.start);
        range.minlen = max(range.minlen, minlen);
        ret = btrfs_trim_fs(root, &range);
        if (ret < 0)