Actually, I've got a patch which tests the variable and returns if it's
null.
Both should work.
+ if (myGlobals.device[actualDeviceId].tcpSession == NULL) {
+ traceEvent(CONST_TRACE_WARNING, "session purge of NULL
myGlobals.device[].tcpSession");
+ return;
+ }
+
Both versions would seem to work, but since Luca was the last one messing
around in there, I'm hoping he'll fix it 'right'...
-----Burton
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf
Of Kouprie, Robbert
Sent: Thursday, July 10, 2003 5:15 AM
To: '[EMAIL PROTECTED]'
Subject: [Ntop-dev] Bug (+fix?) segfault in scanTimedOutTCPSessions
Hi,
Now everything compiles / builds (Thanks to Burton), and the sudden crashes
still lasted, I started digging in the code. I'm running ntop 2.2 from
today's CVS. System is Dual P3-1 GHz, Linux 2.4, glibc 2.3.
First segfault I encountered was in scanTimedOutTCPSessions (mind actual
line number is 453, but I added some debugging print calls).
Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 32771 (LWP 2280)]
0x400916c5 in scanTimedoutTCPSessions (actualDeviceId=1) at sessions.c:459
459 prevSession = theSession =
myGlobals.device[actualDeviceId].tcpSession[idx];
(gdb) bt
#0 0x400916c5 in scanTimedoutTCPSessions (actualDeviceId=1) at
sessions.c:459
#1 0x400809f6 in purgeIdleHosts (actDevice=1) at hash.c:591
#2 0x40087509 in scanIdleLoop (notUsed=0x0) at ntop.c:642
#3 0x40280d53 in pthread_start_thread () from /lib/libpthread.so.0
And in the logs:
Jul 10 13:55:33 xf ntop[2280]: [MSGID00441-sessions] DEBUG: Called
scanTimedoutTCPSessions (device=1, sessions=0)
Jul 10 13:55:33 xf ntop[2280]: [MSGID00451-sessions] DEBUG:
scanTimedoutTCPSessions: _idx=0, idx=0
(Last print statement I added myself).
Now, it seems there are 0 sessions, but we are still accessing
device[actualDeviceId].tcpSession[idx] with an index of 0. This is the point
it segfaults. Shouldn't we bail out if 0 sessions? Like below patch does?
Regards,
-- Robbert
--- sessions.c.orig 2003-07-10 14:10:31.000000000 +0200
+++ sessions.c 2003-07-10 14:13:33.000000000 +0200
@@ -442,6 +442,9 @@
actualDeviceId,
myGlobals.device[actualDeviceId].numTcpSessions);
#endif
+ // If zero sessions, return.
+ if(!myGlobals.device[actualDeviceId].numTcpSessions) return;
+
for(_idx=0; _idx<MAX_TOT_NUM_SESSIONS; _idx++) {
IPSession *nextSession, *prevSession, *theSession;
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