Question Crash

Hello there.

I'm playing around with the code base of TBA mud 2020.
And, found that the mud crash on shutdown. It seems if a mobile start following me. I think, because:

This test crash TBA mud 2020.

goto guard
force guard follow castillo
shutdown

Jan 18 22:54:38 2020 :: Closing link to: Castillo.
Jan 18 22:54:38 2020 :: Saving current MUD time.
Jan 18 22:54:38 2020 :: Normal termination of game.
Jan 18 22:54:38 2020 :: Clearing game world.

Program received signal SIGSEGV, Segmentation fault.
0x00000000004fc6c7 in stop_follower (ch=ch@entry=0x1b7cce0) at utils.c:549
549 for (k = ch->master->followers; k->next->follower != ch; k = k->next);
(gdb)

Bob

This seems eerily familiar.

Crash on Shutdown

I don't know if this was ever solved. A while back I was going to make entries to track values happening at different points at what I thought might be the affected code. But I got frustrated unraveling that knot of code after a while.

Maybe you'll be the one who solves it.

I'll get a look at it tomorrow. It's pretty late now.
I'll have to figure out more about all the codes.

In my example
549 for (k = ch->master->followers; k->next->follower != ch; k = k->next);

Obviously, it crash because k exist, but k->next = NULL, so k->next->follower can't be
accessed and cause the SIGSEGV.

shouldn't there be atlease a security check to avoid a crash. even, if it's just a temporary fix? Something, that will check if (!k->next) whatever code is needed?

i need to understand more this code.
i'll see tomorrow.

Bob

This should be an easy fix. And it's reproducible.

github.com/tbamud/tbamud/pull/75

That did it alright! Thanks Thomas, Welcor and the rest of the mud's development team.