[UBSAN] fix zero size array runtime error

[smuzaffar]

UBSAN IBs generates runtime errors [a]. This change should fix these error. UBSAN complains here https://github.com/cms-sw/cmssw/blob/master/L1Trigger/DTTriggerPhase2/src/MuonPathAssociator.cc#L122-L127 and this can happen when any of SL1metaPrimitives or SL3metaPrimitives is zero size

[a]
https://cmssdt.cern.ch/SDT/jenkins-artifacts/ubsan_logs/CMSSW_13_2_X_2023-05-22-2300/

• 22 L1Trigger/DTTriggerPhase2/src/MuonPathAssociator.cc:122:48: runtime error: variable length array bound evaluates to non-positive value 0
• 20 L1Trigger/DTTriggerPhase2/src/MuonPathAssociator.cc:125:48: runtime error: variable length array bound evaluates to non-positive value 0

[cmsbuild]

+code-checks

Logs: https://cmssdt.cern.ch/SDT/code-checks/cms-sw-PR-41771/35639

• This PR adds an extra 20KB to repository

[cmsbuild]

A new Pull Request was created by @smuzaffar (Malik Shahzad Muzaffar) for master.

It involves the following packages:

• L1Trigger/DTTriggerPhase2 (upgrade, l1)

@epalencia, @cmsbuild, @AdrianoDee, @srimanob, @aloeliger, @cecilecaillol can you please review it and eventually sign? Thanks.
@Martin-Grunewald, @missirol, @JanFSchulte, @battibass this is something you requested to watch as well.
@perrotta, @dpiparo, @rappoccio you are the release manager for this.

cms-bot commands are listed here

[aloeliger]

@smuzaffar I'm afraid I'm not as familiar with this part of L1 code, but this would seem to me to be a fundamental change in function?

[smuzaffar]

@aloeliger , correct this is a fundamental change in function. Someone should review this code. To me continuing the loop if either SL1metaPrimitives or SL3metaPrimitives is empty does not make any sense.

[aloeliger]

@aloeliger , correct this is a fundamental change in function. Someone should review this code. To me continuing the loop if either SL1metaPrimitives or SL3metaPrimitives is empty does not make any sense.

@smuzaffar That's very probably true. I can take a look tomorrow myself, and see if I know an expert who can also weigh in. Does this have a timescale like the ppc fix?

[folguera]

I can look at it tomorrow, I’ve contributed to that code myself in the past so shouldn’t be hard, also @jfernan2 may help here.

[perrotta]

type bug-fix

[aloeliger]

@folguera If you are okay with it, then I will sign off on it.

[aloeliger]

@smuzaffar Apologies, this is off topic, however I was reminded reading this, @cecilecaillol would like to be removed from the l1-l2 github organization, and off of buildbot's ping/permission list. What does it take to do that?

[folguera]

I think the fix is OK, however, there are similar errors on L989 that should be fixed, should we create another PR or should we include this here @smuzaffar I've created a PR to your branch with my proposed solutions smuzaffar#3

[perrotta]

@smuzaffar Apologies, this is off topic, however I was reminded reading this, @cecilecaillol would like to be removed from the l1-l2 github organization, and off of buildbot's ping/permission list. What does it take to do that?

Here is the bot pr to do so: cms-sw/cms-bot#1999

[smuzaffar]

thanks @folguera , I have merged your smuzaffar#3

[cmsbuild]

+code-checks

Logs: https://cmssdt.cern.ch/SDT/code-checks/cms-sw-PR-41771/35720

• This PR adds an extra 20KB to repository

[cmsbuild]

Pull request #41771 was updated. @epalencia, @AdrianoDee, @srimanob, @cmsbuild, @aloeliger can you please check and sign again.

[smuzaffar]

please test

[aloeliger]

I think the fix is OK, however, there are similar errors on L989 that should be fixed, should we create another PR or should we include this here @smuzaffar I've created a PR to your branch with my proposed solutions smuzaffar#3

Okay, then this is good by me. I'll sign when the tests come back.

[cmsbuild]

+1

Summary: https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-e2970c/32905/summary.html
COMMIT: 5393094
CMSSW: CMSSW_13_2_X_2023-05-31-1100/el8_amd64_gcc11
User test area: For local testing, you can use /cvmfs/cms-ci.cern.ch/week1/cms-sw/cmssw/41771/32905/install.sh to create a dev area with all the needed externals and cmssw changes.

Comparison Summary

Summary:

• You potentially added 10 lines to the logs
• Reco comparison results: 0 differences found in the comparisons
• DQMHistoTests: Total files compared: 48
• DQMHistoTests: Total histograms compared: 3221457
• DQMHistoTests: Total failures: 7
• DQMHistoTests: Total nulls: 0
• DQMHistoTests: Total successes: 3221428
• DQMHistoTests: Total skipped: 22
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 47 files compared)
• Checked 207 log files, 159 edm output root files, 48 DQM output files
• TriggerResults: no differences found

[AdrianoDee]

+1

[aloeliger]

+l1

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next master IBs (tests are also fine). This pull request will now be reviewed by the release team before it's merged. @perrotta, @dpiparo, @rappoccio (and backports should be raised in the release meeting by the corresponding L2)

[perrotta]

+1