Re: [PATCH] SELinux: Fix possible NULL pointer dereference inselinux_inode_permission()

[Al Viro]

On Thu, Jan 09, 2014 at 10:31:55AM -0500, Eric Paris wrote:
> Didn't Al find this/something very similar.  I really hate this
> solution.  Why should every LSM try to understand the intimate
> lifetime rules of the parent subsystems?  The real problem is that
> inode_free_security() is being called while the inode is still in use.
>  While I agree with the assessment, I disagree with the solution.  Let
> me try to find where Al and Christoph talked about this....

Because LSM has stuck its fingers into the guts of those filesystems,
obviously.

Just RCU-delay freeing the damn thing and treat NULL ->i_security in
->permission() (which can happen only with MAY_NOT_BLOCK in mask) as
"return -ECHILD and let the caller deal with that".

Modifying every ->destroy_inode() is obviously wrong - there's a lot more
filesystems than LSM buggers in the tree.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/