Messages in this thread | | | Date | Thu, 21 Jun 2018 12:52:40 +0100 | From | Will Deacon <> | Subject | Re: [RFC PATCH] rseq: Avoid infinite recursion when delivering SIGSEGV |
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On Wed, Jun 20, 2018 at 12:55:35PM -0400, Mathieu Desnoyers wrote: > ----- On Jun 20, 2018, at 12:36 PM, Will Deacon will.deacon@arm.com wrote: > > > When delivering a signal to a task that is using rseq, we call into > > __rseq_handle_notify_resume() so that the registers pushed in the > > sigframe are updated to reflect the state of the restartable sequence > > (for example, ensuring that the signal returns to the abort handler if > > necessary). > > > > However, if the rseq management fails due to an unrecoverable fault when > > accessing userspace or certain combinations of RSEQ_CS_* flags, then we > > will attempt to deliver a SIGSEGV. This has the potential for infinite > > recursion if the rseq code continuously fails on signal delivery. > > > > Avoid this problem by using force_sigsegv() instead of force_sig(), which > > is explicitly designed to reset the SEGV handler to SIG_DFL in the case > > of a recursive fault. > > Your approach looks good. One nit below implementation-wise:
Nit accepted :) v2 on its way.
Will
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