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Differential D55861

amd64: check that %cs and %ss values from ucontext fit into registers
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Authored by kib on Mar 15 2026, 7:20 AM.
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jhb
markj
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rG8892176c86db: amd64: check that %cs and %ss values from ucontext fit into registers
Summary
This change only checks that the values from the user-supplied context
are not truncated by C implicit type convertions.  The validity of the
segment selectors is still checked by hardware.

Diff Detail

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rG FreeBSD src repository
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Event Timeline

kib created this revision.Mar 15 2026, 7:20 AM
Herald added a subscriber: imp. · View Herald TranscriptMar 15 2026, 7:20 AM
kib requested review of this revision.Mar 15 2026, 7:20 AM
jhb accepted this revision.Mar 19 2026, 2:39 PM
This revision is now accepted and ready to land.Mar 19 2026, 2:39 PM
kib mentioned this in D55831: x86 FRED: add hardware definitions for the trap frames fields.Mar 19 2026, 3:28 PM
markj added inline comments.Mar 20 2026, 2:33 AM
sys/amd64/amd64/exec_machdep.c
275

These fields are register_t, which is signed.

sys/amd64/ia32/ia32_signal.c
217

... here, the fields are unsigned.

kib updated this revision to Diff 173975.Mar 20 2026, 3:13 AM
kib marked 2 inline comments as done.

Centralize and fix checks.

This revision now requires review to proceed.Mar 20 2026, 3:13 AM
markj added inline comments.Mar 20 2026, 3:16 AM
sys/amd64/ia32/ia32_signal.c
721

This should be updated too?

kib updated this revision to Diff 173976.Mar 20 2026, 3:24 AM
kib marked an inline comment as done.

Missed check.

markj accepted this revision.Mar 20 2026, 4:57 AM
This revision is now accepted and ready to land.Mar 20 2026, 4:57 AM
Closed by commit rG8892176c86db: amd64: check that %cs and %ss values from ucontext fit into registers (authored by kib). · Explain WhyMar 20 2026, 10:50 PM
This revision was automatically updated to reflect the committed changes.
kib added a commit: rG8892176c86db: amd64: check that %cs and %ss values from ucontext fit into registers.

Revision Contents
Changeset List

PathSize
sys/
amd64/
amd64/
19 lines
ia32/
28 lines

Diff 173975

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sys/amd64/amd64/exec_machdep.c

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sys/amd64/ia32/ia32_signal.c

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