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Handle null values in MetaData.mergeMaps, preventing potential NPE #386

Merged
merged 4 commits into from
Nov 29, 2018
Merged

Handle null values in MetaData.mergeMaps, preventing potential NPE #386

merged 4 commits into from
Nov 29, 2018

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fractalwrench
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Goal

Prevent NPE crash when attempting to deliver error reports.

Design

MetaData tab values can be HashMaps, whose entries can be null. MetaData.mergeMaps seemed to assume that the Map was always a ConcurrentHashMap, whose entries cannot be null.

On React Native this manifested as a NPE when merging config.metaData and report.metaData due to app.activeScreen being intermittently recorded as null. This can occur on any platform which uses bugsnag-android, however.

Changeset

Added a null check when adding the base value to the merged map.

Tests

Wrote unit test + mazerunner scenario, and manually verified that valid reports are sent from a React Native example app using a local bugsnag-android artefact.

Review

For the submitter, initial self-review:

  • Commented on code changes inline explain the reasoning behind the approach
  • Reviewed the test cases added for completeness and possible points for discussion
  • A changelog entry was added for the goal of this pull request
  • Check the scope of the changeset - is everything in the diff required for the pull request?
  • This pull request is ready for:
    • Initial review of the intended approach, not yet feature complete
    • Structural review of the classes, functions, and properties modified
    • Final review

For the pull request reviewer(s), this changeset has been reviewed for:

  • Consistency across platforms for structures or concepts added or modified
  • Consistency between the changeset and the goal stated above
  • Internal consistency with the rest of the library - is there any overlap between existing interfaces and any which have been added?
  • Usage friction - is the proposed change in usage cumbersome or complicated?
  • Performance and complexity - are there any cases of unexpected O(n^3) when iterating, recursing, flat mapping, etc?
  • Concurrency concerns - if components are accessed asynchronously, what issues will arise
  • Thoroughness of added tests and any missing edge cases
  • Idiomatic use of the language

@fractalwrench
fix: handle null values in MetaData.mergeMaps
67df1b8 
MetaData tab values can be HashMaps, whose entries can be null. MetaData.mergeMaps seemed to assume
that the Map was always a ConcurrentHashMap, whose values cannot be null, which could lead to a NPE
when merging config.metaData and report.metaData for nullable values, such as activeScreen. Adding a
null check and conditionally adding values fixes this behaviour.
@fractalwrench fractalwrench changed the title Handle null values in MetaData.mergeMaps Handle null values in MetaData.mergeMaps, preventing potential NPE Nov 26, 2018
fractalwrench
fractalwrench commented Nov 26, 2018
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sdk/src/main/java/com/bugsnag/android/MetaData.java
if (baseValue != null
&& baseValue instanceof Map
&& overridesValue instanceof Map) {
if (baseValue instanceof Map && overridesValue instanceof Map) {
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baseValue != null is redundant when also using instanceof

@fractalwrench fractalwrench requested a review from a team November 26, 2018 13:00
bengourley
bengourley previously approved these changes Nov 26, 2018
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This LGTM. I haven't run it yet but the automated test looks good.

At which line would it error before? The Bugsnag.addToTab("Custom", "foo", configMap) or the notify() call? (or both?)

@fractalwrench
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This was originally discovered when setting the codeBundleId in React Native, which in turn sets metadata on the native layer: bugsnag/bugsnag-react-native#291

kattrali
kattrali previously approved these changes Nov 27, 2018
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snmaynard
snmaynard reviewed Nov 27, 2018
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sdk/src/androidTest/java/com/bugsnag/android/MetaDataMergeTest.java Outdated
metaData.addToTab("foo", "bar", nestedMap);
nestedMap.put("whoops", null);

Map<String, Object> mergedMap = MetaData.merge(metaData, metaData).store;
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Can we merge a different metadata? Its weird to read otherwise.

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I have updated the test to generate two different MetaData objects.

sdk/src/androidTest/java/com/bugsnag/android/MetaDataMergeTest.java Outdated
nestedMap.put("whoops", null);

Map<String, Object> mergedMap = MetaData.merge(metaData, metaData).store;
assertFalse(mergedMap.containsKey("whoops"));
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I think this assertion is incorrect. Can you undo the changes to the sdk and check that this fails as you would expect? I would never expect the whoops key to be in this map from reading the test.

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Without the changes, this test fails due to a NPE within MetaData.mergeMaps, which is expected. I have removed the assertFalse statement as I can see it might be confusing. Were there any additional concerns around the assertions?

snmaynard
snmaynard previously requested changes Nov 27, 2018
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Address my comments plz

@fractalwrench fractalwrench dismissed stale reviews from kattrali and bengourley via b0a11da November 27, 2018 10:29
@fractalwrench fractalwrench dismissed snmaynard’s stale review November 27, 2018 10:30

comments addressed

@fractalwrench
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@snmaynard I believe I have addressed the comments, are you happy with the updates?

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I pinged you with my concerns - we can discuss tomorrow!

@fractalwrench fractalwrench merged commit a8eaa15 into master Nov 29, 2018
@fractalwrench fractalwrench deleted the metadata-merge-fix branch November 29, 2018 14:40
lemnik added a commit that referenced this pull request Jun 2, 2021
@lemnik
Merge pull request #386 from bugsnag/PLAT-6025/remove-jcenter-references
1fb1218 
fix(gradle): replaced jcenter with mavenCentral
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@snmaynard snmaynard snmaynard approved these changes

@kattrali kattrali kattrali left review comments

@bengourley bengourley bengourley left review comments

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4 participants
@fractalwrench @snmaynard @kattrali @bengourley