Bug 182021 - tethereal has a memory leak
Summary: tethereal has a memory leak
Alias: None
Product: Fedora
Classification: Fedora
Component: ethereal
Version: rawhide
Hardware: All
OS: Linux
Target Milestone: ---
Assignee: Radek Vokal
QA Contact:
Depends On:
TreeView+ depends on / blocked
Reported: 2006-02-19 06:45 UTC by Dave Jones
Modified: 2015-01-04 22:25 UTC (History)
1 user (show)

Clone Of:
Last Closed: 2006-02-24 07:40:51 UTC

Attachments (Terms of Use)

Description Dave Jones 2006-02-19 06:45:30 UTC
I accidentally left tethereal running on my home dsl firewall all day.
When I noticed the rest of the network was behaving really slowly, I
investigated, and found this in top output..

Mem:    105596k total,   103804k used,     1792k free,      116k buffers
Swap:  1277944k total,   621384k used,   656560k free,     6252k cached

12984 root      16   0  621m  75m 1268 D  0.3 73.5  22:38.68 tethereal

before starting tethereal , there was no swap used at all (it's normal state on
this box)

(01:46:01:davej@firewall:~)$ free
             total       used       free     shared    buffers     cached
Mem:        105596     103468       2128          0        100       7572
-/+ buffers/cache:      95796       9800
Swap:      1277944     621040     656904

(01:48:53:davej@firewall:~)$ sudo kill -9 12984

(01:49:34:davej@firewall:~)$ free
             total       used       free     shared    buffers     cached
Mem:        105596      33332      72264          0        296      10004
-/+ buffers/cache:      23032      82564
Swap:      1277944      11476    1266468

Comment 1 Dave Jones 2006-02-19 08:07:44 UTC
running this under valgrind for a few minutes is.. enlightening.

valgrind --leak-check=yes --show-reachable=yes tethereal -V -i eth0

among lots of smaller allocations reported are..

==24353== 586,560 bytes in 2,264 blocks are possibly lost in loss record 44 of 46
==24353==    at 0x48044B3: memalign (vg_replace_malloc.c:332)
==24353==    by 0x4804509: posix_memalign (vg_replace_malloc.c:384)
==24353==    by 0xBE0488: (within /usr/lib/libglib-2.0.so.0.902.4)
==24353==    by 0xBE1717: g_slice_alloc (in /usr/lib/libglib-2.0.so.0.902.4)
==24353==    by 0xBD18A2: g_mem_chunk_alloc (in
/usr/lib/libglib-2.0.so.0.902.4)==24353==    by 0x509191D:
proto_register_protocol (in /usr/lib/libethereal.so.0.0.1)
==24353==    by 0x50C7483: proto_register_3com_xns (in
==24353==    by 0x564D346: register_all_protocols (in /usr/lib/libethereal.so.0.0.1)
==24353==    by 0x509691A: proto_init (in /usr/lib/libethereal.so.0.0.1)
==24353==    by 0x5082B4D: epan_init (in /usr/lib/libethereal.so.0.0.1)
==24353==    by 0x1BF46: main (in /usr/sbin/tethereal)
==24353== 1,504,512 bytes in 6,048 blocks are still reachable in loss record 45
of 46
==24353==    at 0x48044B3: memalign (vg_replace_malloc.c:332)
==24353==    by 0x4804509: posix_memalign (vg_replace_malloc.c:384)
==24353==    by 0xBE0488: (within /usr/lib/libglib-2.0.so.0.902.4)
==24353==    by 0xBE1717: g_slice_alloc (in /usr/lib/libglib-2.0.so.0.902.4)
==24353==    by 0xBD18F9: g_mem_chunk_new (in /usr/lib/libglib-2.0.so.0.902.4)
==24353==    by 0x50AD0C5: tvbuff_init (in /usr/lib/libethereal.so.0.0.1)
==24353==    by 0x5082B26: epan_init (in /usr/lib/libethereal.so.0.0.1)
==24353==    by 0x1BF46: main (in /usr/sbin/tethereal)
==24353== 21,612,761 bytes in 29,858 blocks are still reachable in loss record
46 of 46
==24353==    at 0x48051F9: malloc (vg_replace_malloc.c:149)
==24353==    by 0xBD1715: g_malloc (in /usr/lib/libglib-2.0.so.0.902.4)
==24353==    by 0xBD2F8E: g_log_set_handler (in
/usr/lib/libglib-2.0.so.0.902.4)==24353==    by 0x1BEA6: main (in
==24353== LEAK SUMMARY:
==24353==    definitely lost: 22,187 bytes in 2,830 blocks.
==24353==      possibly lost: 586,560 bytes in 2,264 blocks.
==24353==    still reachable: 23,878,820 bytes in 46,086 blocks.
==24353==         suppressed: 0 bytes in 0 blocks.

Comment 2 Radek Vokal 2006-02-23 08:06:39 UTC
It really looks bad. I've asked ethereal developers and here is what they
suggest to try first

From gharris@sonic.net 

Are you running Tethereal either

    1) without the "-w" option, so it dissects packets in order to display them


    2) with the "-R" option, so it dissects packets in order to do read filtering?

If so, don't - the dissection produces a lot of state information, as well as
packet reassembly information, and, by design, that information doesn't get
freed until Tethereal exits.

*Some* of it might be freeable while the capture is being done, but some of it
is information that could conceivably be needed at some arbitrary later point in
the dissection of the packet stream, so it can't be freed.


It's true that with -R option I see lower mem consuption but still some small
leaks are present. 

Comment 3 Dave Jones 2006-02-24 03:32:09 UTC
as shown in the comment above, I was using  -V -i eth0

if it's designed this way, it's arguably horribly broken by design.

Comment 4 Radek Vokal 2006-02-24 07:40:51 UTC
Yep, it's a design issue keeping the persistent data to produce sequences. 

From gharris@sonic.net
So it was, as I suspected, run without "-w", so it was dissecting.

We might be able to avoid *persistently* saving reassembled packet data,
although to make that work in Ethereal we need to make random access, including
random access to compressed files, efficient (so that when you click on a packet
whose contents are reassembled, we can re-read the packets from which it was
reassembled and reconstruct the reassembled data).

We might also be able to have a global "don't do any reassembly" flag.

That would probably get rid of the biggest consumers of memory from dissection.
 There's other state information that would persist; an option to disable *that*
would mean that, for a lot of protocols, replies won't be dissectable (as you
need information from the request to dissect the reply; it might, or 
might not, be possible to get rid of that information once the reply's
dissected, as some of it might need to be kept around for retransmissions and
the like).  (Note, BTW, that tcpdump, when run without the "-S" option, also
keeps persistent state information around to produce relative sequence numbers.)


Comment 5 Radek Vokal 2006-02-24 07:55:31 UTC
Oh nice, there's also a Wiki page about memory consumption


Note You need to log in before you can comment on or make changes to this bug.