Re: [kbuild] Re: [PATCH 2/2] btrfs: Use btrfs_try_lock_balance in btrfs_ioctl_balance

[Nikolay Borisov <nborisov@suse.com>]

On 4.05.22 г. 9:46 ч., Dan Carpenter wrote:
> Hi Nikolay,
> 
> url:    https://github.com/intel-lab-lkp/linux/commits/Nikolay-Borisov/Refactor-btrfs_ioctl_balance/20220503-163837
> base:   https://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux.git  for-next
> config: i386-randconfig-m021-20220502 (https://download.01.org/0day-ci/archive/20220504/202205041423.NVVJIHSj-lkp@intel.com/config )
> compiler: gcc-11 (Debian 11.2.0-20) 11.2.0
> 
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@intel.com>
> Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
> 
> smatch warnings:
> fs/btrfs/ioctl.c:4493 btrfs_ioctl_balance() error: double free of 'bargs'
> 
> vim +/bargs +4493 fs/btrfs/ioctl.c


Yep, a genuine braino, the fix is to remove either of the calls. I 
personally would go with the one before mnt_drop_write so that we drop 
the write ASAP but in the end I doubt it makes any practical difference. 
David care to fold this or shall I resend?

> 
> c9e9f97bdfb64d Ilya Dryomov         2012-01-16  4484
> 0f89abf56abbd0 Christian Engelmayer 2015-10-21  4485  	kfree(bctl);
> ed0fb78fb6aa29 Ilya Dryomov         2013-01-20  4486  out_unlock:
> c9e9f97bdfb64d Ilya Dryomov         2012-01-16  4487  	mutex_unlock(&fs_info->balance_mutex);
> ed0fb78fb6aa29 Ilya Dryomov         2013-01-20  4488  	if (need_unlock)
> c3e1f96c37d0f8 Goldwyn Rodrigues    2020-08-25  4489  		btrfs_exclop_finish(fs_info);
> ed0fb78fb6aa29 Ilya Dryomov         2013-01-20  4490  out:
> c696e46e6ec2b3 Nikolay Borisov      2022-05-03  4491  	kfree(bargs);
>                                                                ^^^^^
> 
> e54bfa31044d60 Liu Bo               2012-06-29  4492  	mnt_drop_write_file(file);
> c746db1b6ed99f Nikolay Borisov      2022-03-30 @4493  	kfree(bargs);
>                                                                ^^^^^
> 
> Freed twice.
> 
> c9e9f97bdfb64d Ilya Dryomov         2012-01-16  4494  	return ret;
> c9e9f97bdfb64d Ilya Dryomov         2012-01-16  4495  }
>