720704 - Avoid setting an alternative stack for signals if there is already one

Status: RESOLVED FIXED

(Toolkit :: Crash Reporting, defect)

Description

[Mike Hommey [:glandium]]

The software in which breakpad is hooked may well have already set an alternative stack for signals for separate reasons. Breakpad should use that alternative stack if it's large enough.

http://code.google.com/p/google-breakpad/issues/detail?id=464

Comment 1

[Mike Hommey [:glandium]]

Attachment: Avoid setting an alternative stack for signals if there is already one

Comment 2

[(not currently active) Ted Mielczarek]

Comment on attachment 591101 [details] [diff] [review]
Avoid setting an alternative stack for signals if there is already one

Review of attachment 591101 [details] [diff] [review]:
-----------------------------------------------------------------

This looks fine. Needs to land upstream as well.

::: toolkit/crashreporter/google-breakpad/src/client/linux/handler/exception_handler.cc
@@ -189,5 @@
>    // We use this value rather than SIGSTKSZ because we would end up overrunning
>    // such a small stack.
>    static const unsigned kSigStackSize = 8192;
>  
> -  signal_stack = malloc(kSigStackSize);

Does calling sigaltstack hand over ownership of the stack memory?

Comment 3

[Mike Hommey [:glandium]]

(In reply to Ted Mielczarek [:ted, :luser] from comment #2)
> Does calling sigaltstack hand over ownership of the stack memory?

No, so effectively, this is leaked memory. But that is a feature of the existing code already.

Comment 4

[Mike Hommey [:glandium]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/e9dcf2a2a097

Comment 5

[Ed Morley [:emorley]]

https://hg.mozilla.org/mozilla-central/rev/e9dcf2a2a097