linux-kernel - Re: [PATCH] btrfs: Fix a memory leak in btrfs_ioctl

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Message-ID: <c7d16718-1071-2b57-fc77-968945cfb4f5@suse.com>
Date:   Thu, 21 Apr 2022 14:25:39 +0300
From:   Nikolay Borisov <nborisov@...e.com>
To:     Haowen Bai <baihaowen@...zu.com>, Chris Mason <clm@...com>,
        Josef Bacik <josef@...icpanda.com>,
        David Sterba <dsterba@...e.com>
Cc:     linux-btrfs@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] btrfs: Fix a memory leak in btrfs_ioctl_balance()



On 21.04.22 г. 14:21 ч., Nikolay Borisov wrote:
> 
> 
> On 21.04.22 г. 12:51 ч., Haowen Bai wrote:
>> Free "bargs" before return.
>>
>> Signed-off-by: Haowen Bai <baihaowen@...zu.com>
>> ---
>>   fs/btrfs/ioctl.c | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
>> index f08233c2b0b2..d4c8bea914b7 100644
>> --- a/fs/btrfs/ioctl.c
>> +++ b/fs/btrfs/ioctl.c
>> @@ -4389,13 +4389,13 @@ static long btrfs_ioctl_balance(struct file 
>> *file, void __user *arg)
>>               /* this is (2) */
>>               mutex_unlock(&fs_info->balance_mutex);
>>               ret = -EINPROGRESS;
>> -            goto out;
>> +            goto out_bargs;
>>           }
>>       } else {
>>           /* this is (1) */
>>           mutex_unlock(&fs_info->balance_mutex);
>>           ret = BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS;
>> -        goto out;
>> +        goto out_bargs;
>>       }
>>   locked:
> 
> I think this is a better fix:
> 
> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> index 7a6974e877f4..906ed1b93654 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -4391,15 +4391,13 @@ static long btrfs_ioctl_balance(struct file 
> *file, void __user *arg)
>                          goto again;
>                  } else {
>                          /* this is (2) */
> -                       mutex_unlock(&fs_info->balance_mutex);
>                          ret = -EINPROGRESS;
> -                       goto out;
> +                       goto out_bargs;
>                  }
>          } else {
>                  /* this is (1) */
> -               mutex_unlock(&fs_info->balance_mutex);
>                  ret = BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS;
> -               goto out;
> +               goto out_bargs;
>          }
> 
>   locked:
> 


Actually to simplify further:

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 7a6974e877f4..bbda55d41a06 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -4353,6 +4353,7 @@ static long btrfs_ioctl_balance(struct file *file, void __user *arg)
         bargs = memdup_user(arg, sizeof(*bargs));
         if (IS_ERR(bargs)) {
                 ret = PTR_ERR(bargs);
+               bargs = NULL;
                 goto out;
         }
  
@@ -4391,13 +4392,11 @@ static long btrfs_ioctl_balance(struct file *file, void __user *arg)
                         goto again;
                 } else {
                         /* this is (2) */
-                       mutex_unlock(&fs_info->balance_mutex);
                         ret = -EINPROGRESS;
                         goto out;
                 }
         } else {
                 /* this is (1) */
-               mutex_unlock(&fs_info->balance_mutex);
                 ret = BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS;
                 goto out;
         }
@@ -4406,7 +4405,7 @@ static long btrfs_ioctl_balance(struct file *file, void __user *arg)
         if (bargs->flags & BTRFS_BALANCE_RESUME) {
                 if (!fs_info->balance_ctl) {
                         ret = -ENOTCONN;
-                       goto out_bargs;
+                       goto out;
                 }
  
                 bctl = fs_info->balance_ctl;
@@ -4420,18 +4419,18 @@ static long btrfs_ioctl_balance(struct file *file, void __user *arg)
  
         if (bargs->flags & ~(BTRFS_BALANCE_ARGS_MASK | BTRFS_BALANCE_TYPE_MASK)) {
                 ret = -EINVAL;
-               goto out_bargs;
+               goto out;
         }
  
         if (fs_info->balance_ctl) {
                 ret = -EINPROGRESS;
-               goto out_bargs;
+               goto out;
         }
  
         bctl = kzalloc(sizeof(*bctl), GFP_KERNEL);
         if (!bctl) {
                 ret = -ENOMEM;
-               goto out_bargs;
+               goto out;
         }
  
         memcpy(&bctl->data, &bargs->data, sizeof(bctl->data));
@@ -4457,12 +4456,11 @@ static long btrfs_ioctl_balance(struct file *file, void __user *arg)
         }
  
         kfree(bctl);
-out_bargs:
+out:
         kfree(bargs);
         mutex_unlock(&fs_info->balance_mutex);
         if (need_unlock)
                 btrfs_exclop_finish(fs_info);
-out:
         mnt_drop_write_file(file);
         return ret;
  }