snd_dummy: Avoid NULL dereferences in dummy_chan_io()
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Authored by christos on Tue, Nov 5, 9:27 PM.

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markj
emaste
dev_submerge.ch

Summary

Sponsored by: The FreeBSD Foundation
MFC after: 2 days

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rG FreeBSD src repository

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Tests Skipped

Build Status

Buildable 60413
Build 57297: arc lint + arc unit

Event Timeline

christos created this revision.Tue, Nov 5, 9:27 PM

Herald added a subscriber: imp. · View Herald TranscriptTue, Nov 5, 9:27 PM

christos requested review of this revision.Tue, Nov 5, 9:27 PM

Harbormaster completed remote builds in B60413: Diff 146077.Tue, Nov 5, 9:27 PM

christos added a parent revision: D47459: snd_dummy: Fix callout(9) races.Tue, Nov 5, 9:27 PM

christos added a child revision: D47461: sound: Fix chn_trigger() and vchan_trigger() races.

christos mentioned this in D47462: sound: Fix hot-unload panics.Tue, Nov 5, 9:31 PM

When are these fields null?

In D47460#1083229, @markj wrote:

When are these fields null?

I couldn't pinpoint exactly, but I am pretty sure D47462 and D47459 fixed the cases where these fields could end up null. However, I think it wouldn't hurt to be extra safe here.

There may be cases where NULL checks like these eliminate some crashes but leave races that still exist but are harder to hit.

In D47460#1083443, @emaste wrote:

There may be cases where NULL checks like these eliminate some crashes but leave races that still exist but are harder to hit.

As I said, the two patches mentioned most likely fix those races, so I guess we could abandon this one.

christos abandoned this revision.Sun, Nov 10, 4:22 PM

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sys/

dev/

sound/

dummy.c

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Diff 146077

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snd_dummy: Avoid NULL dereferences in dummy_chan_io()AbandonedPublicActions