enter_syscall
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Authored by nikita_elyzion.net on Aug 2 2016, 8:19 PM.

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rS304113: MFC: r303685
rS304104: MFC: r303685
rS303685: truss: fix uninitialized trussinfo->curthread in add_threads()/enter_syscall

Summary

trussinfo->curthread must be initialized before calling enter_syscall(),
it is used by t->proc->abi->fetch_args() .
Without that truss is segfaulting and the attached program crash also.

It can be reproduced by trying to attach a binary which is doing a
while (1) usleep(1);

Test Plan

Try to attach a few times a program which is doing a while (1) usleep(1) or any program doing a lot of short syscalls.

Diff Detail

Repository

rS FreeBSD src repository - subversion

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Unit

No Test Coverage

Build Status

Buildable 4686
Build 4740: arc lint + arc unit

Event Timeline

nikita_elyzion.net updated this revision to Diff 18968.Aug 2 2016, 8:19 PM

nikita_elyzion.net retitled this revision from to truss: fix uninitialized trussinfo->curthread in add_threads()/enter_syscall.

nikita_elyzion.net updated this object.

nikita_elyzion.net edited the test plan for this revision. (Show Details)

Herald added subscribers: Contributor Reviews (src), imp. · View Herald TranscriptAug 2 2016, 8:19 PM

bapt added a reviewer: jhb.Aug 2 2016, 8:21 PM

Hmm, you actually already know the thread (it's 't'). I think this is fallout from considering removing 'curthread' (but something I haven't done yet). I think you can just do 'info->curthread = t;' before enter_syscall() in place of find_thread().

(Long term I think I'd like to pass 't' down to the ABI callbacks and remove curthread completely. trussinfo itself is an odd duck as it's really just global variables but obfuscated)

bapt edited edge metadata.Aug 2 2016, 8:46 PM

bapt added a subscriber: bapt.

updating with jhb comments

jhb accepted this revision.Aug 2 2016, 10:04 PM

jhb edited edge metadata.

This revision is now accepted and ready to land.Aug 2 2016, 10:04 PM

Closed by commit rS303685: truss: fix uninitialized trussinfo->curthread in add_threads()/enter_syscall (authored by bapt). · Explain WhyAug 2 2016, 10:47 PM

This revision was automatically updated to reflect the committed changes.