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Bug #637

Segfault linked to NICK handling

Added by raph raph 12 days ago. Updated 12 days ago.

Status:
New
Priority:
Normal
Assignee:
-
Target version:
-
Start date:
2018-10-31
Due date:
% Done:

0%

Patch Available:
Found in Versions:
Confirmed:
No
Branch:
Security:
Help Needed:

Description

Hello,
I've had several crashes using bip 0.9.0-rc1-git

For example:

(gdb) bt                                                                                                                                                                                                             
#0  0x00005555555638dc in write_line (cn=cn@entry=0x0, line=line@entry=0x5555559427b0 "NICK Trou\r\n") at src/connection.c:430                                                                                       
#1  0x000055555556b6bc in irc_line_write (l=<optimized out>, c=0x0) at src/line.c:41                                                                                                                                 
#2  0x0000555555566d1e in irc_001 (server=0x55555593e970, server=0x55555593e970, line=0x5555559357b0) at src/irc.c:173                                                                                               
#3  irc_dispatch_server (bip=<optimized out>, server=0x55555593e970, line=0x5555559357b0) at src/irc.c:453                                                                                                           
#4  0x000055555556900d in irc_dispatch (bip=bip@entry=0x7fffffffb4b0, l=l@entry=0x55555593e970, line=line@entry=0x5555559357b0) at src/irc.c:1260                                                                    
#5  0x000055555556ac85 in bip_on_event (bip=bip@entry=0x7fffffffb4b0, conn=0x5555558b8750) at src/irc.c:2490                                                                                                         
#6  0x000055555556af73 in irc_main (bip=0x7fffffffb4b0) at src/irc.c:2565                                                                                                                                            
#7  0x000055555555b4a0 in main (argc=<optimized out>, argv=<optimized out>) at src/bip.c:1359        

I've also another coredump (but for some reason, gdb does not get lines correctly):

Program terminated with signal SIGSEGV, Segmentation fault.
#0  0x000055e45d24d8dc in ?? ()
(gdb) info reg
rax            0x55e45d759a80   94439308892800
rbx            0x0      0
rcx            0x7f45d71b5b00   139937938365184
rdx            0x12     18
rsi            0x55e45d7599e0   94439308892640
rdi            0x55e45d759a80   94439308892800
rbp            0x0      0x0
rsp            0x7ffc0674a1c0   0x7ffc0674a1c0
r8             0xeec0   61120
r9             0x20     32
r10            0x747e21756f725420       8394183543729837088
r11            0x312e383740756f72       3543831766742953842
r12            0x7ffc0674a220   140720416793120
r13            0x1      1
r14            0x0      0
r15            0x8      8
rip            0x55e45d24d8dc   0x55e45d24d8dc
eflags         0x10206  [ PF IF RF ]

(gdb) x/1s $rdi
0x55e45d759a80: ":Trou NICK Trou\r\n" 

(gdb) x/1s $rsi
0x55e45d7599e0: ":Trou NICK Trou\r\n" 

But i'm not quite sure why it crashes.

The following patch should help if there's a race (between increment and realloc) but I think it's unlikely to be the problem.

diff --git a/src/irc.c b/src/irc.c
index f46f4dd..08c9cb9 100644
--- a/src/irc.c
+++ b/src/irc.c
@@ -575,10 +575,11 @@ static void bind_to_link(struct link *l, struct link_client *ic)
        int i = l->l_clientc;

        LINK(ic) = l;
-       l->l_clientc++;
-       l->l_clientv = bip_realloc(l->l_clientv, l->l_clientc *
+       l->l_clientv = bip_realloc(l->l_clientv, (l->l_clientc + 1) *
                        sizeof(struct link_client *));
        l->l_clientv[i] = ic;
+    /* Increment after, to avoid any race condition */
+       l->l_clientc++;
 }

 void unbind_from_link(struct link_client *ic)

History

#1 Updated by raph raph 12 days ago

I think it may be related to a logic problem due to SSL certs trust:

31-10-2018 14:49:49 SSL cert check: now at depth=0
31-10-2018 14:49:49 Subject: /CN=XXXX
31-10-2018 14:49:49 Issuer: /C=US/O=Let's Encrypt/CN=Let's Encrypt Authority X3
31-10-2018 14:49:49 Basic mode; peer certificate NOT in store, rejecting it!
31-10-2018 14:49:49 ERROR: SSL cert check failed at depth=0: certificate rejected (28)
140737354060736:error:1416F086:SSL routines:tls_process_server_certificate:certificate verify failed:../ssl/statem/statem_clnt.c:1230:
31-10-2018 14:49:49 ERROR: Certificate check failed: certificate rejected (28)!
31-10-2018 14:49:49 ERROR: Error on fd 1 (state 9)
31-10-2018 14:49:49 DEBUG: New socket still not connected (2)
31-10-2018 14:49:49 ERROR: [XXX] read_lines error, closing...

then i get later a trust request for the certificate BUT at the same time, bip connects to another server, with a valid certificate
14:51 [XXX] !b.i.p This server SSL certificate was not accepted because it is not in your store of trusted certificates:
14:51 [XXX] !b.i.p Subject: /CN=XXX
14:51 [XXX] !b.i.p Issuer:  /C=US/O=Let's Encrypt/CN=Let's Encrypt Authority X3
[...]
14:51 [XXX] !b.i.p WARNING: if you've already trusted a certificate for this server before, that probably means it has changed.
14:51 [XXX] !b.i.p If so, YOU MAY BE SUBJECT OF A MAN-IN-THE-MIDDLE ATTACK! PLEASE DON'T TRUST THIS CERTIFICATE IF YOU'RE NOT SURE THIS IS NOT THE CASE.
14:51 [XXX] !b.i.p Type /QUOTE BIP TRUST OK to trust this certificate, /QUOTE BIP TRUST NO to discard it.

then
(gdb) bt
#0  0x000055555556470c in write_line (cn=cn@entry=0x0, line=line@entry=0x555555770440 "NICK Trou\r\n") at src/connection.c:430
#1  0x000055555556c60c in irc_line_write (l=<optimized out>, c=0x0) at src/line.c:41
#2  0x0000555555567bc4 in irc_001 (server=0x55555575cac0, server=0x55555575cac0, line=0x55555574d090) at src/irc.c:173
#3  irc_dispatch_server (bip=<optimized out>, server=0x55555575cac0, line=0x55555574d090) at src/irc.c:453
#4  0x0000555555569ed5 in irc_dispatch (bip=bip@entry=0x7fffffffb480, l=l@entry=0x55555575cac0, line=line@entry=0x55555574d090) at src/irc.c:1261
#5  0x000055555556bb91 in bip_on_event (bip=bip@entry=0x7fffffffb480, conn=0x555555743de0) at src/irc.c:2491
#6  0x000055555556bea3 in irc_main (bip=0x7fffffffb480) at src/irc.c:2566
#7  0x000055555555bea8 in main (argc=<optimized out>, argv=<optimized out>) at src/bip.c:1359
(gdb)

if look at the connecionts:

(gdb) print server->_link_c->link->l_clientv->_link_c->type
$15 = 3
(gdb) print server->_link_c->link->l_clientv[0]->_link_c->type
$16 = 3
(gdb) print server->_link_c->link->l_clientv[1]->_link_c->type                                                                                                                                                       
$17 = 3
(gdb) print server->_link_c->link->l_clientv[2]->_link_c->type                                                                                                                                                       
$18 = 3

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