Messages in this thread | | | Date | Thu, 21 Jun 2018 15:57:16 +0100 | From | Will Deacon <> | Subject | Re: [PATCH v2] rseq: Avoid infinite recursion when delivering SIGSEGV |
| |
On Thu, Jun 21, 2018 at 10:44:37AM -0400, Mathieu Desnoyers wrote: > ----- On Jun 21, 2018, at 7:54 AM, 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. In doing so, remove rseq_signal_deliver() from the > > internal rseq API and have an optional struct ksignal * parameter to > > rseq_handle_notify_resume() instead. > > > > Signed-off-by: Will Deacon <will.deacon@arm.com> > > --- > > > > RFC v1 -> v2: Kill rseq_signal_deliver() > > I actually meant to kill _rseq_handle_notify_resume introduced by > your patch, not rseq_signal_deliver(). > > Please keep rseq_signal_deliver() as a static inline, and just remove > the _rseq_handle_notify_resume() by changing the signature of > rseq_handle_notify_resume to take an extra sig argument (which can > be NULL).
Sorry, I misunderstood what you were asking for. I'll spin a v3 in a bit with rseq_signal_deliver() reintroduced.
Will
| |