Possibly something weird about talloc?

[Richard Sharpe]

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?

-- 
Regards,
Richard Sharpe
(何以解憂？唯有杜康。--曹操)