Saturday, June 04, 2016

AH00051: child pid ? exit signal Segmentation fault (11), possible coredump in ?

I ran into the below segmentation fault in apache accompanied by high CPU usage in the server:
[Fri Jun 03 06:00:01.270303 2016] [core:notice] [pid 29628:tid 140412199950208] AH00051: child pid 2343 exit signal Segmentation fault (11), possible coredump in /tmp/apache-coredumps
After debugging what the problem was, I concluded that mod proxy was the culprit. There is an apparent recursive bug. I decided not to report it because it was hard to replicate (this happened only late at night) and there was a workaround I could use. This error happened when there was a first request for a resource that the proxied worker could not serve, apache tried to use a specific document for the error but a configuration issue would try to pull such document from the worker as well. Since the document is not in the remote server mod proxy will enter an infinite loop resulting in an apache crash. Most likely a recursion related bug. Clearly resolving the configuration issue to make sure the document is pulled from the local apache hides this potential mod proxy bug.
[Fri Jun 03 05:56:40.831871 2016] [proxy:error] [pid 2343:tid 140411834115840] (502)Unknown error 502: [client 192.168.0.180:58819] AH01084: pass request body failed to 172.16.2.2:8443 (sample.com)
[Fri Jun 03 05:56:40.831946 2016] [proxy:error] [pid 2343:tid 140411834115840] [client 192.168.0.180:58819] AH00898: Error during SSL Handshake with remote server returned by /sdk
[Fri Jun 03 05:56:40.831953 2016] [proxy_http:error] [pid 2343:tid 140411834115840] [client 192.168.0.180:58819] AH01097: pass request body failed to 172.16.2.2:8443 (sample.com) from 192.168.0.180 ()
[Fri Jun 03 05:56:40.844138 2016] [proxy:error] [pid 2343:tid 140411834115840] (502)Unknown error 502: [client 192.168.0.180:58819] AH01084: pass request body failed to 172.16.2.2:8443 (sample.com)
[Fri Jun 03 05:56:40.844177 2016] [proxy:error] [pid 2343:tid 140411834115840] [client 192.168.0.180:58819] AH00898: Error during SSL Handshake with remote server returned by /html/error/503.html
[Fri Jun 03 05:56:40.844185 2016] [proxy_http:error] [pid 2343:tid 140411834115840] [client 192.168.0.180:58819] AH01097: pass request body failed to 172.16.2.2:8443 (sample.com) from 192.168.0.180 ()

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