[U-Boot] [PATCH 1/1] ubifs: avoid possible NULL dereference

[Heinrich Schuchardt]

On 11/21/2017 09:23 PM, Ladislav Michl wrote:
> On Tue, Nov 21, 2017 at 07:45:03PM +0100, Heinrich Schuchardt wrote:
>> If 'file' cannot be allocated due to an out of memory
>> situation, do not dereference it.
>>
>> When debugging this patch also avoids a misleading message
>> "cannot find next direntry, error %d" in case of an out of
>> memory situation. It is sufficent to write
>> "%s: Error, no memory for malloc!\n" in this case.
>>
>> Reported-by: Alex Sadovsky <nable.maininbox at googlemail.com>
>> Signed-off-by: Heinrich Schuchardt <xypron.glpk at gmx.de>
>> ---
>>   fs/ubifs/ubifs.c | 5 ++---
>>   1 file changed, 2 insertions(+), 3 deletions(-)
>>
>> diff --git a/fs/ubifs/ubifs.c b/fs/ubifs/ubifs.c
>> index 4465523d5f..313dee0579 100644
>> --- a/fs/ubifs/ubifs.c
>> +++ b/fs/ubifs/ubifs.c
>> @@ -403,8 +403,7 @@ static int ubifs_finddir(struct super_block *sb, char *dirname,
>>   	dir = kzalloc(sizeof(struct inode), 0);
>>   	if (!file || !dentry || !dir) {
>>   		printf("%s: Error, no memory for malloc!\n", __func__);
>> -		err = -ENOMEM;
>> -		goto out;
>> +		goto out_nomem;
>>   	}
>>   
>>   	dir->i_sb = sb;
>> @@ -424,7 +423,6 @@ static int ubifs_finddir(struct super_block *sb, char *dirname,
>>   		err = PTR_ERR(dent);
>>   		goto out;
>>   	}
>> -
>>   	file->f_pos = key_hash_flash(c, &dent->key);
>>   	file->private_data = dent;
>>
>    
> This hunk should be probably droped.
> 
>> @@ -463,6 +461,7 @@ out:
>>   
>>   out_free:
>>   	kfree(file->private_data);
> 
> Now question is why is file->private_data ever assigned as it seems nothing
> works with it.

Good catch.

Do we need file and dentry at all in the function?

Unfortunately the file cannot be compiled on x86 cf.
https://lists.denx.de/pipermail/u-boot/2017-November/312166.html

Best regards

Heinrich


> 
>> +out_nomem:
>>   	free(file);
>>   	free(dentry);
>>   	free(dir);
>> -- 
>> 2.11.0
>>
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