WebContent processes crash when the network process crashes with pending connection requests

[Ryosuke Niwa]

When the network process crashes after a CreateNetworkConnectionToWebProcess is sent from UI process (in response to GetNetworkProcessConnection) but before the reply is provided, the originating WebContent process crashes inside ensureNetworkProcessConnection.

Here's one way to reproduce this crash:
1. Start two WebContent process A and B
2. Kill the network process
3. Load a new page in process A
4. Suspend the network process newly created in step 3 (kill -STOP pid)
5. Load a new page in process B
6. Kill the network process suspended in step 4
7. WebContent process B crashes.

In the actual crash happening in the field, step 4 is likely some sort of a spin or a delay in IPC. What’s important is the network process crasehs after process B requested a new network connection but before fulfilling the reply. In that case, networkProcessCrashedOrFailedToLaunch would simply return 0 in GetNetworkProcessConnection::DelayedReply, and this causes the originating WebContent process to crash inside ensureNetworkProcessConnection.

[Ryosuke Niwa]

<rdar://problem/30359835>

[Ryosuke Niwa]

Created attachment 314370 [details]
Fixes the bug

[Ryosuke Niwa]

Ping reviewers.

[Tim Horton]

Comment on attachment 314370 [details]
Fixes the bug

View in context: https://bugs.webkit.org/attachment.cgi?id=314370&action=review

> Source/WebKit2/UIProcess/API/Cocoa/WKProcessPoolPrivate.h:78
> +- (pid_t)_networkProcessIdentifier;

Availability macros.

[Ryosuke Niwa]

Created attachment 314504 [details]
Patch for landing

[WebKit Commit Bot]

Comment on attachment 314504 [details]
Patch for landing

Clearing flags on attachment: 314504

Committed r219087: <http://trac.webkit.org/changeset/219087>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.