Possibly something weird about talloc?

[Ralph Boehme]

On Sun, Feb 07, 2016 at 02:13:38PM -0800, Richard Sharpe wrote:
> Hi folks,
> 
> I have modified gdb-heap (ssh://git.fedorahosted.org/git/gdb-heap.git) to
> show useful info about talloc chunks in the heap as well.
> 
> In looking at the results, I see many cases like this:
> 
> -----------------------------------------
>    178: 0x00007f98cdc927f0 -> 0x00007f98cdc9288f      160 bytes
> talloc:talloc chunk:48 bytes:"struct parmlist_entry" |a0 b4 cb cd 98 7f 00
> 00 40 be cd cd 98 7f 00 00 00 00 00 00 00 00 00 00 c0 bd cd cd 98 7f 00 00
> 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 35 07 7f c8 98 7f 00 00 30
> 00 00 00 00 00 00 00 70 0c 15 e8 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> 00 00 00 00 00 00 80 00 00 00 00 00 00 00 a0 be cd cd 98 7f 00 00 a0 9f c9
> cd 98 7f 00 00 90 04 c9 cd 98 7f 00 00 20 be cd cd 98 7f 00 00
> |.....^?.. at ....^?...............^?..................5.^?..^?..0.......p....................................^?.......^?.......^?..
> ....^?..|
> ------------------------------------------
> 
> It contains a pointer in the chunk header pointing to the structure type.
> 
> However, I also see entries like this:
> 
> -------------------------------------------------
>    177: 0x00007f98cdc92760 -> 0x00007f98cdc927ef      144 bytes
> talloc:talloc chunk:25 bytes:"/home/samba/etc/smb.conf" |30 b5 cb cd 98 7f
> 00 00 00 00 00 00 00 00 00 00 a0 b4 cb cd 98 7f 00 00 00 00 00 00 00 00 00
> 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 c0 27 c9 cd 98 7f 00 00
> 19 00 00 00 00 00 00 00 70 0c 15 e8 00 00 00 00 00 00 00 00 00 00 00 00 00
> 00 00 00 00 00 00 00 40 ec c8 cd 98 7f 00 00 2f 68 6f 6d 65 2f 73 61 6d 62
> 61 2f 65 74 63 2f 73 6d 62 2e 63 6f 6e 66 00 8f c9 cd 98 7f 00 00
> |0....^?...............^?...........................'...^?..........p.......................@
> ....^?../home/samba/etc/smb.conf.....^?..|
> --------------------------------------------------
> 
> The pointer in the header that should point to the allocation location or
> type points to the data.
> 
> When does this happen?

sorry, can't help. But fwiw, maybe this one can:
<https://github.com/nccgroup/libtalloc>

-Ralph

-- 
SerNet GmbH, Bahnhofsallee 1b, 37081 Göttingen
phone: +49-551-370000-0, fax: +49-551-370000-9
AG Göttingen, HRB 2816, GF: Dr. Johannes Loxen
http://www.sernet.de,mailto:kontakt@sernet.de