[nhofmeyr@sysmocom.de: Re: Help required on : Reproducing the issue] - OpenBSC

15 Dec 2016

On Wed, Dec 14, 2016 at 02:24:23PM +0000, Pravin Kumaravel Manoharan wrote:
...
                  I tried to reproduce the issue
mentioned in http://lists.osmocom.org/pipermail/openbsc/2016-December/009966.html .
 While running sanitizer script I got an error  gcc: error: unrecognized command line
option '-fsanitize=undefined'
 So, to avoid this I removed the option from CFLAGS+= and CXXFLAGS+= . 
That's odd, all compilers I've used so far apparently support
	 -fsanitize=address -fsanitize=undefined
anyway:

...
  Then I got the following error  :
 ERROR: Address Sanitizer: heap-use-after-free on address 0x60380000a00c at pc 0x436acf bp
0x7ffc4456d4e0 sp 0x7ffc4456d4d8
 but I didn't get any  SIGSEGV in sgsn_create_pdp_ctx(). 
Have you reversed the order of those two lines I wrote about earlier to fix the
use-after-free yet?

This is what I wrote:

...
  I found a use-after-free which isn't the cause for
above asan failure:

   gsm0408_gprs_access_cancelled(mm, GMM_CAUSE_GPRS_NOTALLOWED);
   LOGMMCTXP(LOGL_NOTICE, mm, "No PDP context to deactivate\n");

 gsm0408_gprs_access_cancelled() calls mm_ctx_cleanup_free(), and after that the
 local mm is non-NULL but freed. Change the order to:

   LOGMMCTXP(LOGL_NOTICE, mm, "No PDP context to deactivate\n");
   gsm0408_gprs_access_cancelled(mm, GMM_CAUSE_GPRS_NOTALLOWED);

 (This second issue is shown when removing test_pdp_deactivation_with_pdp_ctx()
 from test_pdp_deactivation()) 
If you do that, do you still get any asan errors?

I hope that you'll be able to reproduce the segfault, since it was seen on both
our build server as well as my own laptop...

~N

-- 
- Neels Hofmeyr &lt;nhofmeyr(a)sysmocom.de&gt;          http://www.sysmocom.de/
=======================================================================
* sysmocom - systems for mobile communications GmbH
* Alt-Moabit 93
* 10559 Berlin, Germany
* Sitz / Registered office: Berlin, HRB 134158 B
* Geschäftsführer / Managing Directors: Harald Welte

----- End forwarded message -----

-- 
- Neels Hofmeyr &lt;nhofmeyr(a)sysmocom.de&gt;          http://www.sysmocom.de/
=======================================================================
* sysmocom - systems for mobile communications GmbH
* Alt-Moabit 93
* 10559 Berlin, Germany
* Sitz / Registered office: Berlin, HRB 134158 B
* Geschäftsführer / Managing Directors: Harald Welte