[Asterisk-code-review] chan sip: Fix segfault during module unload (asterisk[13])

[Michael Kuron]

Michael Kuron has posted comments on this change. ( https://gerrit.asterisk.org/4494 )

Change subject: chan_sip: Fix segfault during module unload
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Patch Set 1:

Here's a bit more information on the second segfault (the first one is detailed on JIRA). That's the one I fix by turning off SA_RESTART on the SIGURG handler (it seemed like an oversight that this flag is present because it prevents all those pthread_kill(..., SIGURG) from actually stopping any blocking syscalls, which is their sole purpose).

When ast_tcptls_client_start ends with return NULL, the segfault happens immediately, and comes with what looks like a stack corruption. If you have any suggestions why that happens, I'm happy to try and fix that segfault as well. I think there is potentially another race condition that could still trigger the segfault even without the SA_RESTART flag: if the module unload is executed (and consequently, pthread_kill(..., SIGURG) is run) after the threadinfo has been created but before the thread has reached ast_connect in ast_tcptls_client_start, the blocking syscall is never interrupted and runs into the stack-corrupting segfault after it times out.

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Gerrit-MessageType: comment
Gerrit-Change-Id: I76fd9d47d56e4264e2629bce8ec15fecba673e7b
Gerrit-PatchSet: 1
Gerrit-Project: asterisk
Gerrit-Branch: 13
Gerrit-Owner: Michael Kuron <m.kuron at gmx.de>
Gerrit-Reviewer: Anonymous Coward #1000019
Gerrit-Reviewer: Michael Kuron <m.kuron at gmx.de>
Gerrit-HasComments: No