Re: [External] : Re: CVE-2024-26920: tracing/trigger: Fix to return error if failed to alloc snapshot

["gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>]

On Thu, Apr 18, 2024 at 01:06:42PM +0000, Siddh Raman Pant wrote:
> On Thu, Apr 18 2024 at 14:34:57 +0200, gregkh@linuxfoundation.org
> wrote:
> > On Thu, Apr 18, 2024 at 11:59:41AM +0000, Siddh Raman Pant wrote:
> > > Hi Greg,
> > > 
> > > > In the Linux kernel, the following vulnerability has been resolved:
> > > > 
> > > > tracing/trigger: Fix to return error if failed to alloc snapshot
> > > > 
> > > > Fix register_snapshot_trigger() to return error code if it failed to
> > > > allocate a snapshot instead of 0 (success). Unless that, it will register
> > > > snapshot trigger without an error.
> > > 
> > > This commit is problematic on 4.19.y, 5.4.y, 5.10.y, and 5.15.y,
> > > and should be reversed, and this CVE should be rejected for those
> > > versions.
> > 
> > Then please submit a patch for this.
> 
> Sure.
> 
> 
> > But note, CVEs are not for specific versions, sorry.  We give a hint as
> > to what kernel versions might be affected, but we don not assign CVE to
> > versions.
> 
> Cool.
> 
> > > 
> > > The return value should be 0 on failure, because in the functions
> > > event_trigger_callback() and event_enable_trigger_func(), we have:
> > > 
> > > 	ret = cmd_ops->reg(glob, trigger_ops, trigger_data, file);
> > > 	/*
> > > 	 * The above returns on success the # of functions enabled,
> > > 	 * but if it didn't find any functions it returns zero.
> > > 	 * Consider no functions a failure too.
> > > 	 */
> > > 	if (!ret) {
> > > 		ret = -ENOENT;
> > > 
> > > Thus, the commit breaks this assumption.
> > > 
> > > This commit needs b8cc44a4d3c1 ("tracing: Remove logic for registering
> > > multiple event triggers at a time") as a prerequisite, as it removes
> > > the above.
> > 
> > Should we just take that patch instead?
> 
> The series in which the patch is posted is here:
> - https://lore.kernel.org/lkml/cover.1644010575.git.zanussi@kernel.org/
> - https://lore.kernel.org/lkml/cover.1641823001.git.zanussi@kernel.org/
> 
> Seems like some good tracing subsystem refactoring. So if I understand
> Documentation/process/stable-kernel-rules.rst correctly, I would say we
> should not.

So the documentation on the commit here is wrong (i.e. wrong Fixes:
tag?)  If so, that needs to be said somewhere...

thanks,

greg k-h