segfault in in gearman_client_run_tasks()

[Sven Nierlein]

When i run gearman_client_run_tasks() i get a segfault in client()
gdb backtrace is:

Program received signal SIGSEGV, Segmentation fault.
0x080ae180 in client ()
(gdb)
(gdb) bt
#0 0x080ae180 in client ()
#1 0xb7c9742c in gearman_universal_set_error (universal=..., rc=GEARMAN_NO_SERVERS, function=0xb7ca26e0 "_client_run_task", position=0xb7ca2611 "libgearman/run.cc:54",
    format=0xb7ca2600 "no servers added") at libgearman/error.cc:120
#2 0xb7c9b322 in _client_run_task (client=0x80ae060, task=0x80f7090) at libgearman/run.cc:54
#3 0xb7c93ec3 in _client_run_tasks (client=0x80ae060) at libgearman/client.cc:1238
#4 0xb7c94577 in gearman_client_run_tasks (client=0x80ae060) at libgearman/client.cc:1472

I tried stable 0.28 and latest trunk. The error is the same. It had worked with v0.25, but i did not try 0.26 and 0.27 yet.

Thanks

[Brian Aker (brianaker)]

Do you have an example of your code? It looks like client has never been set in the task object.

[Sven Nierlein (sven-nierlein)]

The error occurs in one of my test cases:
https://github.com/sni/mod_gearman/blob/master/t/02-full.c#L375

First i call
gearman_client_add_task_background(client, ...)
and then
gearman_client_run_tasks( client )

The client should be ok and should have servers set.

[Brian Aker (brianaker)]

Pull lp:gearmand and see what error you get. The only way I believe this bug could happen would be because of any issue your code (basically a bad task).

[Sven Nierlein (sven-nierlein)]

Tree is up to date at revision 502.

The error is the same but the line numbers have changed.

#0 0x080ab120 in client ()
#1 0xb7fcc9e4 in gearman_universal_set_error (universal=..., rc=GEARMAN_NO_SERVERS, function=0xb7fd837c "_client_run_task",
    position=0xb7fd82be "libgearman/run.cc:64", format=0xb7fd82ad "no servers added") at libgearman/error.cc:128
#2 0xb7fd099e in _client_run_task (task=0x80d9830) at libgearman/run.cc:64
#3 0xb7fc934c in _client_run_tasks (client=0x80ab000) at libgearman/client.cc:1252
#4 0xb7fc9ab4 in gearman_client_run_tasks (client=0x80ab000) at libgearman/client.cc:1488

In addition to the segfault, i get lots of messages like this:

Assertion "packet->universal" failed for function "gearman_packet_free" likely for "Packet that is being freed has not been allocated, most likely this is do to freeing a gearman_task_st or other object twice", at libgearman/packet.cc:257

the only free i use, is the gearman_client_task_free_all(client) after gearman_client_run_tasks(). But i don't think thats the point here, because the segfault is already before the free.

[Brian Aker (brianaker)]

I think I found out what was happening here. After a task has been deleted it needs to check to see if it is the active task, and if that is the case set the client's active to null as well.