Differential D56580

kexec: Disallow kexec_load if securelevel > 0
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Authored by jhibbits on Apr 22 2026, 3:52 PM.

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rGe3e8ec2ab620: kexec: Disallow kexec_load if securelevel > 0

Summary

kexec_load() + reboot is intended to be equivalent to a system reboot.
However kexec_load() can load arbitrary data as the target kernel,
leading to execution of arbitrary code, even though it's effectively in
a new context. Rather than being equivalent to a system reboot, it's
also equivalent to kldload(), which loads arbitrary code into the
running kernel. Since kldload() is blocked at securelevel 1, also block
kexec_load().

Reported by: markj
Fixes: e02c57ff3 ("kern: Introduce kexec system feature (MI)")
MFC after: 2 weeks
Sponsored by: Hewlett Packard Enterprise

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rG FreeBSD src repository

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Event Timeline

jhibbits created this revision.Apr 22 2026, 3:52 PM

Herald added subscribers: olce, imp. · View Herald TranscriptApr 22 2026, 3:52 PM

jhibbits requested review of this revision.Apr 22 2026, 3:52 PM

Harbormaster completed remote builds in B72448: Diff 176118.Apr 22 2026, 3:52 PM

MFC after: 2 weeks

It looks like kexec was never MFCed?

This revision is now accepted and ready to land.Apr 22 2026, 4:05 PM

In D56580#1295238, @markj wrote:

MFC after: 2 weeks

It looks like kexec was never MFCed?

Oops, I thought I had gotten kexec_load in just before stable/15 branched, but guess not. No need to MFC, then.

Closed by commit rGe3e8ec2ab620: kexec: Disallow kexec_load if securelevel > 0 (authored by jhibbits). · Explain WhyApr 22 2026, 4:30 PM

This revision was automatically updated to reflect the committed changes.

jhibbits added a commit: rGe3e8ec2ab620: kexec: Disallow kexec_load if securelevel > 0.

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sys/

kern/

3 lines

Diff 176119

sys/kern/kern_kexec.c

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