---
- branch: MAIN
  date: Wed Jan 10 20:51:11 UTC 2018
  files:
  - new: '1.110'
    old: '1.109'
    path: src/sys/arch/amd64/amd64/trap.c
    pathrev: src/sys/arch/amd64/amd64/trap.c@1.110
    type: modified
  id: 20180110T205111Z.3ebbbf2ded7b5247ddda945a6fbb42136bd2b51d
  log: |
    Restrict the check: SMAP faults are always protection violations, as the
    SDM points out, so make sure we have PGEX_P. This way NULL dereferences -
    which are caused by an unmapped VA, and therefore are not protection
    violations - don't take this branch, and don't display a misleading
    "SMAP" in ddb.

    Adding a PGEX_P check, or not, does not essentially change anything from
    a security point of view, it's just a matter of what gets displayed when
    a fatal fault comes in.

    I didn't put PGEX_P until now, because initially when I wrote the SMAP
    implementation Qemu did not always receive the fault if the PGEX_P check
    was there, while a native i5 would. I'm unable to reproduce this issue
    with a recent Qemu, so I assume I did something wrong when testing in the
    first place.
  module: src
  subject: 'CVS commit: src/sys/arch/amd64/amd64'
  unixtime: '1515617471'
  user: maxv