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Re: panic due to SMAP or SMEP? (Patrick Welche) writes:

>On Mon, Oct 30, 2017 at 12:48:17PM +0900, Ryota Ozaki wrote:
>> I encountered a panic perhaps related to SMAP or SMEP
>> (see attached photos) with latest -current.
>> Does the panic ring the bell of someone?

>Just that the first of the two panics I posted about today contains

>#1  0xffffffff8096c23c in vpanic (
>    fmt=fmt@entry=0xffffffff810e573d "prevented access to %p (SMAP)",
>    ap=ap@entry=0xffffe4011dda9558) at ../../../../kern/subr_prf.c:342

That's just a special kind of uvmfault (i.e. dereferencing invalid pointer).
It used to trap only unmapped addresses, now it also traps access to userland
memory outside of the copyin/copyout functions. Apparently accesses to
the first page (i.e. from a NULL pointer) are also included.

                                Michael van Elst
                                "A potential Snark may lurk in every tree."

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