1286709 - Missing return value check for GetApzc()

Status: RESOLVED FIXED

(Core :: Graphics: Layers, defect)

Description

[Nicholas Nethercote [inactive]]

ApplyAsyncTransformToScrollbarForContent() calls GetApzc() but doesn't null-check the result.

Comment 1

[Nicholas Nethercote [inactive]]

Attachment: Add a missing null check for a GetApzc() call

kats, I hope an early return is appropriate here, but I'm not certain.

All the other calls to GetApzc() are null-checked.

Comment 2

[Kartikaya Gupta (email:[e-mail])]

Comment on attachment 8770750 [details] [diff] [review]
Add a missing null check for a GetApzc() call

Review of attachment 8770750 [details] [diff] [review]:
-----------------------------------------------------------------

I think it should be safe to MOZ_ASSERT that it is not null there. The LayerMetrics passed in to this function must retyrn true from IsValid(), based on the call site, and if you trace backwards all the valid LayerMetrics that reach that point must have returned true from LayerIsScrollbarTarget. That function checks that the apzc is non-null.

Were you actually seeing a case where this caused a crash? If so I'll need to look more carefully but otherwise I would prefer the assert to an early return.

Comment 3

[Nicholas Nethercote [inactive]]

Attachment: Add a missing null check for a GetApzc() call

It was static analysis (Coverity).

Comment 4

[Kartikaya Gupta (email:[e-mail])]

Comment on attachment 8770786 [details] [diff] [review]
Add a missing null check for a GetApzc() call

Review of attachment 8770786 [details] [diff] [review]:
-----------------------------------------------------------------

r=me, please update commit message also

Comment 5

[Nicholas Nethercote [inactive]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/994235fda74bd1d05003546f98d23e46f6ceecef
Bug 1286709 - Assert the non-nullness of an GetApzc() call's return value. r=kats.

Comment 6

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/994235fda74b