[rrd-developers] RFC: [PATCH] Portability by avoiding PATH_MAX

Steven Hartland killing at multiplay.co.uk
Thu May 8 03:05:21 CEST 2014

----- Original Message ----- 
From: "Svante Signell" <svante.signell at gmail.com>
To: "rrdtool dev list" <rrd-developers at lists.oetiker.ch>
Sent: Tuesday, April 29, 2014 1:35 PM
Subject: [rrd-developers] RFC: [PATCH] Portability by avoiding PATH_MAX

> Hello,
> Here are updated patches for rrdtool/rrd_client.c and
> rrdtool/rrd_daemon.c. We had some discussions in August last year. I
> created a branch and the diffs are against latest git. I've run the
> code, especially rrd_daemon with valgrind under Linux, but need some
> help to check that also rrd_client works OK (maybe rrd_daemon too). Can
> you help me with test cases to run the execute the code modified paths.
> I know one application using rrdtool, lm-sensors (build-dependency on
> librrd2-dev), but am not sure my computers have the sensors to be a good
> test case.
> Note that the modified functions get_path() and get_abs_path() are
> static, so they don't change the API.

This looks like it would cause a lot of unnessary malloc free surely
the correct fix for this is to fix the OS config to define PATH_MAX.

Quick look at the patches also show its quite broken:-

+  tmp = malloc(len);
+  snprintf(tmp, len, "%s/%s", config_base_dir, *filename);
   *filename = tmp;
+  free(tmp);

So you just malloced some memory, assigned the pointer to it then freed
the memory, so your now going to get a use after free and BOOM!


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