Re: bug: double free

Hallo John,

"John E. Davis" <[email protected]> wrote:
> Jörg Sommer <[email protected]> wrote:
>> (gdb) bt
>> #0  0x0fd7d36c in raise () from /lib/libc.so.6
>> #1  0x0fd7efec in abort () from /lib/libc.so.6
>> #2  0x0fdbbdf4 in __libc_message () from /lib/libc.so.6
>> #3  0x0fdc3c38 in malloc_printerr () from /lib/libc.so.6
>> #4  0x0fdc60a8 in free () from /lib/libc.so.6
>> #5  0x0ff8c56c in SLfree () from /lib/libslang.so.2
>> #6  0x100476c8 in slrn_free (s=0x0) at /home/joerg/svn/slrn/src/strutil.c:308
>
> slrn_free will not do anything if its argument is NULL, as #6 above
> suggests.  Are you able to reproduce this?

Yes.

Breakpoint 1, slrn_art_free_article_line (l=0x101cbf88) at /home/joerg/svn/slrn/src/art.c:570
570             slrn_free ((char *) l->buf);
$143 = {next = 0x101cc1e0, prev = 0x101cbf60, flags = 0, 
  buf = 0x101cd2d8 "\017��\017��believe that whole question is in topic. \nIs there any way to recognize ( and then shape ) p2p traffic which is encrypted?\nModern p2p clients have this ability moreover some of them have this "...}
$144 = (Slrn_Article_Line_Type *) 0x101cbf88
(gdb) step
slrn_free (
    s=0x101cd2d8 "\017��\017��believe that whole question is in topic. \nIs there any way to recognize ( and then shape ) p2p traffic which is encrypted?\nModern p2p clients have this ability moreover some of them have this "...) at /home/joerg/svn/slrn/src/strutil.c:308
308        if (s != NULL)
(gdb) 
307     {
(gdb) 
308        if (s != NULL)
(gdb) 
309           SLfree (s);
(gdb) 
0x10052190 in call___do_global_ctors_aux ()
(gdb) cont
Continuing.
*** glibc detected *** /home/joerg/svn/slrn/src/objs/slrn: double free or corruption (out): 0x101cd2d8 ***

slrn_free() is not called with NULL.

This is the article:
--------------------
Path: alea.gnuu.de!postmaster
From: [email protected] (sAwAr)
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Subject: How to fight with encrypted p2p
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=0A=0AHi=0A=0AI believe that whole question is in topic. =0AIs there any wa=
y to recognize ( and then shape ) p2p traffic which is encrypted?=0AModern =
p2p clients have this ability moreover some of them have this enabled by de=
fault. =0ANow I'm using ipp2p for iptables but as I know this doesn't recog=
nize encrypted traffic.=0A=0AThanks in advance.=0A=0APozdrawiam=0ASzymon Tu=
rkiewicz=0A
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-----[END]---------------

Bye, Jörg.
-- 
Roesen's Law (http://www.bruhaha.de/laws.html):
Sobald ein Troll, DAU oder Elch im Lauf eines Threads auf heftige Kritik
stößt, argumentiert er mit der Arroganz des Kritikers. Dies kann auch
vorsorglich erfolgen.

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