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Differential D25966

Preserve ASLR vm_map flags across fork.
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Authored by brooks on Aug 5 2020, 7:50 PM.
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markj
kib
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rS364087: MFC r363966:
rS363966: Preserve ASLR vm_map flags across fork
Summary

In the most common case (fork+execve) this doesn't matter, but further
attempts to apply entropy would fail in (e.g.) a pre-fork server.

Reported by: Alfredo Mazzinghi

Test Plan

A variant of this patch preserving an additional local flag
works in CheriBSD.

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rS FreeBSD src repository - subversion
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Event Timeline

brooks requested review of this revision.Aug 5 2020, 7:50 PM
brooks created this revision.
Harbormaster completed remote builds in B32782: Diff 75448.Aug 5 2020, 7:50 PM
kib added inline comments.Aug 5 2020, 8:25 PM
sys/vm/vm_map.c
4102 ↗(On Diff #75448)

() are excessive.
Also I suggest to move the line right after new_map assignment (line 4098), no need for blank lines around.

sys/vm/vm_map.h
226 ↗(On Diff #75448)

It is single-use symbol, it is easier to read code when flags are listed explicitly in vmspace_fork().

brooks updated this revision to Diff 75449.Aug 5 2020, 8:52 PM
  • Relocate flags assignment and don't use a variable.
Harbormaster completed remote builds in B32783: Diff 75449.Aug 5 2020, 8:52 PM
brooks marked an inline comment as done.Aug 5 2020, 8:52 PM
kib accepted this revision.Aug 5 2020, 9:11 PM
This revision is now accepted and ready to land.Aug 5 2020, 9:11 PM
markj accepted this revision.Aug 6 2020, 3:48 PM
Closed by commit rS363966: Preserve ASLR vm_map flags across fork (authored by brooks). · Explain WhyAug 6 2020, 4:20 PM
This revision was automatically updated to reflect the committed changes.
brooks added a commit: rS363966: Preserve ASLR vm_map flags across fork.
Herald added a subscriber: imp. · View Herald TranscriptAug 6 2020, 4:20 PM
brooks added a commit: rS364087: MFC r363966:.Aug 10 2020, 6:26 PM

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head/
sys/
vm/
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Diff 75509

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head/sys/vm/vm_map.c

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