Re: [PATCH] Handle access of a target that has been removed

[Lee Duncan <lduncan@suse.com>]

On 10/17/2015 05:57 AM, FUJITA Tomonori wrote:
> On Tue, 13 Oct 2015 11:10:17 -0700
> Lee Duncan <lduncan@suse.com> wrote:
> 
>> Hello:
>>
>> I recently got a report of a tgtd core dump from our opencloud
>> group. The stack trace showed that a strcmp against a NULL was causing
>> the failure:
>>
>> ----------------------------------------------------------------
>> Program terminated with signal 11, Segmentation fault.
>> (gdb) bt
>> #0  0x00007fa701817576 in __strcmp_sse42 () from /lib64/libc.so.6
>> #1  0x0000000000408012 in target_find_by_name (
>>     name=0x6ac16f "iqn.2010-10.org.openstack:volume-e812c705-80bc-4064-a84c-5559cda8b1ca") at iscsi/target.c:216
>> #2  0x0000000000406042 in login_start (conn=0x6abea8) at iscsi/iscsid.c:478
>> #3  0x0000000000406e77 in cmnd_exec_login (conn=<optimized out>)
>>     at iscsi/iscsid.c:654
>> #4  cmnd_execute (conn=<optimized out>) at iscsi/iscsid.c:914
>> #5  iscsi_rx_handler (conn=0x6abea8) at iscsi/iscsid.c:2064
>> #6  0x0000000000409e98 in iscsi_tcp_event_handler (fd=<optimized out>, 
>>     events=1, data=0x63a480 <target_list>) at iscsi/iscsi_tcp.c:158
>> #7  0x0000000000418f1e in event_loop () at tgtd.c:272
>> #8  0x0000000000419405 in main (argc=1, argv=<optimized out>) at tgtd.c:438
>> ----------------------------------------------------------------
>>
>> It looks like target_find_by_name() uses tgt_targetname(), but doesn't
>> account for the fact that it can return a NULL when the target being
>> looked up does not (now) exist:
> 
> Thanks for the patch. But I'm confused why this happens. target with
> the same tid as iscsi_target must exist?
> 

No, I believe this is happening because the targets are getting
dynamically removed. But I will verify that. Because if tgt_targetname()
can return a NULL (as apparently it did this time), there are probably
other places in the code that need to check for that.

-- 
Lee Duncan