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[Bug runtime/9937] verify user-space build-ids


------- Additional Comments From mjw at redhat dot com  2009-03-16 21:45 -------
(In reply to comment #4)
> 1. Where the checking should happen,  especially after vma module tracking code
> is visible by Mark.  Currently,  I put the check in stap_uprobe_process_found
> or stap_uprobe_vmchange_found

Yes, this is where I would also hook in for tracking the vma->module map. I
don't think you need to hook stap_uprobe_process_found explicitly for an EXEC
finder.callback since the finder.vm_callback will give you also matches for the
EXEC itself. But maybe I am missing a timing issue.

> 2. Searching the found task in _stp_modules through tgt->pathname/vm_path.  Is
> it enough?

I believe this is enough, the vm_path is the complete canonical path. We do need
to make sure to register the module names also with their full canonical names.

> 3. Once build-id validation failed,  just return error? Any more cleanup need
> to be done?

I would only produce a warning, we are also just continuing when we cannot
verify the build-id. Or, if we want to make that also an error then we probably
have to do what stap_uprobe_change() at the end when things fail, set the state
to error and _stp_exit().

> 4. More consideration?

I am not sure about limiting the build-id comparison to MAXSTRINGLEN. If we are
afraid of people creating scripts against modules with absurdly big build-ids
then we should block those in the translator imho.

-- 


http://sourceware.org/bugzilla/show_bug.cgi?id=9937

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