[gentoo-user] realloc() failure in motion

[William Kenworthy]

Hi, I am setting up some  cameras (esp32cam) and intended to use motion
for them but it crashes on startup with a realloc() error. The system is
an up to date arm64 (odroid N2+), mostly stable. Has anyone seen this
before?

BillK


ha /etc/motion # /usr/bin/motion -c /etc/motion/motion.conf -k 9 -d 9
[0:motion] [NTC] [ALL] conf_load: Processing thread 0 - config file
/etc/motion/motion.conf
[0:motion] [NTC] [ALL] config_camera: Processing camera config file
/etc/motion/camera0.conf
[0:motion] [NTC] [ALL] read_camera_dir: Processing config file
/etc/motion/motion.conf
[0:motion] [NTC] [ALL] config_camera: Processing camera config file
/etc/motion/motion.conf
realloc(): invalid old size
Aborted

[Nuno Silva]

Could you try to get a stack trace from that?


I've never used "motion" and I don't know its source code, but [1] makes
me wonder if the failure could be happening in [2].

OTOH, from the output, "motion" has entered config_camera() and gone
beyond [2] a second time before the realloc() abort - but could these
two calls have received the same cnt?

From my very little understanding of the code and from your output, it
looks like "motion" might be processing motion.conf twice (the
"Processing thread 0 [...]" line precedes a call to conf_process(), as
does "Processing camera config file"). Is this intended?

[1] https://github.com/Motion-Project/motion/blob/HEAD/src/conf.c#L3204
[2] https://github.com/Motion-Project/motion/blob/HEAD/src/conf.c#L3180

(Links are to HEAD, as that's what I started reading.)

--
Nuno Silva

[William Kenworthy]

Yep, that was the problem - it was when looking the output from strace
thst it hit me.  Its self caused in that I had a camera description file
and also set a config variable to read the directory that the files are
stored in.  From google hits on reallocate failures like this, its
likely a lack of protection in the code for reading the config files
multiple times at the root of the problem.  The documentation could be
clearer about this, but thats on me.

BillK