[lttng-dev] LTTng 2.6.0: Corrupt metadata?

[Neil Bryan]

Hello LTTng devs,

I am experiencing a strange problem with what I believe is corrupt metadata. This is seen on v2.6.0 of LTTng.

If I try and parse recovered traces using Babeltrace, it fails with a segmentation fault.

nbryan at meteorubuntu-OptiPlex-7010:/data/nbryan/Meteor/altera_trace$ babeltrace --help
BabelTrace Trace Viewer and Converter 1.0.0-rc1

nbryan at meteorubuntu-OptiPlex-7010:/data/nbryan/Meteor/altera_trace$ babeltrace auto-20150304-091109/
Segmentation fault (core dumped)

I thought it may be worth a look at the metadata file and I observed the following (these are just three examples):

Environment:
env {
     hostname = "socfpga_cyclone5";
     domain = "kernel";
     sysname = "Linux";
     kernel_release = "3.10.31-ltsi-05035-g801a40f";
     kernel_version = "#3 SMP Tue Mar 3 17:31:45 GMT 2015";
     tracer_name = "lttng-modules";
     tracer_major = 2;
     tracer_minor = 6;
     tracer_patchlevel = 0;
};

event {
     name = "syscall_exit_recvmmsg";
     id = 921;
     stream_id = 0;
     fields := struct {
           integer { size = 32; align = 32; signed = 1; encoding = none; base = 10; } _ret;
           integer { size = 32; align = 32; signe   WСu?­©)2ѕИN№d™Џ‰n®    и   Ђ     d = 0; encoding = none; base = 16; } _mmsg;
           integer { size = 32; align = 32; signed = 0; encoding = none; base = 16; } _timeout;
     };
};

Decoded binary values:
00h,00h,00h,57h,1Dh,D1h,75h,3Fh,ADh,A9h,29h,32h,BEh,C8h,4Eh,B9h,64h,99h,8Fh,14h,89h,6Eh,AEh,00h,00h,00h,00h,E8h,7Fh,00h,00h,00h,80h,00h,00h,
00h,00h,00h,01h,08h

event {
     name = "syscall_exit_getcpu";
     id = 903;
     stream_id = 0;
     fields := struct {
           integer { size = 32; align = 32; signed = 1; encoding = none; base = 10; } _ret;
           integer { size = 32; align = 32; signed = 0; encoding = none; base = 16; } _cpup;
           integer { size = 32; align = 32; signed = 0; encoding = none; base = 16; } _nodep;
           integer { size = 32; align = 32; signed = 0; encoding = none; base =   WСu?­©)2ѕИN№d™Џ‰n®    и   Ђ      16; } _tcache;
     };
};

Decoded binary values:
00h,00h,00h,57h,1Dh,D1h,75h,3Fh,ADh,A9h,29h,32h,BEh,C8h,4Eh,B9h,64h,99h,8Fh,14h,89h,6Eh,AEh,00h,00h,00h,00h,E8h,7Fh,00h,00h,00h,80h,00h,00h,00h,
00h,00h,01h,08h

event {
     name = "syscall_exit_fstatat64";
     id = 886;
     stream_id = 0;
     fields := struct {
           integer { size = 32; align = 32; signed = 1; encoding = none; base = 10; } _ret;
           integer { size = 32; align = 32; signed = 1; encod   WСu?­©)2ѕИN№d™Џ‰n®    и   Ђ     ing = none; base = 10; } _dfd;
           string _filename;
           integer { size = 32; align = 32; signed = 0; encoding = none; base = 16; } _statbuf;
           integer { size = 32; align = 32; signed = 1; encoding = none; base = 10; } _flag;
     };
};

Decoded binary values:
00h,00h,00h,57h,1Dh,D1h,75h,3Fh,ADh,A9h,29h,32h,BEh,C8h,4Eh,B9h,64h,99h,8Fh,14h,89h,6Eh,AEh,00h,00h,00h,00h,E8h,7Fh,00h,00h,00h,80h,00h,00h,
00h,00h,00h,01h,08h

In a metadata file containing 7200 lines, I see this corruption 74 times.

I also notice that the header of the metadata file contains something very similar:

57h,1Dh,D1h,75h,3Fh,ADh,A9h,29h,32h,BEh,C8h,4Eh,B9h,64h,99h,8Fh,14h,89h,6Eh,AEh,00h,00h,00h,00h,D8h,27h,00h,00h,00h,80h,00h,00h,00h,00h,00h,01h,08h

This appears identical to the other instances, less the first three 00h bytes.

Now it may be intentional to squirt binary data into what is essentially  a text file, but it looks suspicious. Can anyone shed any light on what is happening here?
Is the metadata file supposed to have any binary data in it at all?

Thanks,

Neil.




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