Re: [PATCH 1/1] Fix memory leak in kernfs_security_xattr_set and kernfs_security_xattr_set

[Casey Schaufler <casey@schaufler-ca.com>]

On 6/1/2018 9:29 AM, CHANDAN VN wrote:
>>>  I agree that the fix can be done simply by using "false" for 
>>>  smack_inode_getsecurity(), but what happens with kernfs_node_setsecdata()
>>>  and smack_inode_notifysecctx(). kernfs_node_setsecdata() is probably ignorable
>>>  but smack_inode_notifysecctx() is sending the "ctx" to smack_inode_setsecurity()
>>>  and since "ctx" would be NULL because we used "false", smack_inode_setsecurity()
>>>  becomes dummy.
>  
>> Thank you for pointing this out. You're right, there's more
>> at issue here than changing the alloc flag will fix. I think
>> that calling smack_inode_getsecurity() from smack_inode_getsecctx()
>> is making the code more complicated than it needs to be. I will
>> have a patch shortly.
> If you think the patch would take time or is complicated, I suggest that the kfree() fix should go
> to fix the leaks for now.

Heavens no! The patch is very simple. I'm building a kernel with
it now, and should have it tested and posted within a few hours.
The implementation of smack_inode_getsecctx() that's there is
understandable, but wrong. There's a much better way to do the
job.