Description of problem:
Customer is running 7.9 and had to enable disable_changed wwids. After enabling this multipathd started coredumping.

Version-Release number of selected component (if applicable):
device-mapper-multipath-0.4.9-134.el7_9.x86_64

How reproducible:
Easy to reproduce at customer

Steps to Reproduce:
1.Enable disable_changed_wwids
2.multipathd segfaults
3.

Actual results:
multipathd segfaults

Expected results:
Known fix needed to prevent this

Additional info:

Analyzing the core file and why multipathd is segfaulting


Program terminated with signal 11, Segmentation fault.

#0  uev_update_path (vecs=0x55ce6e3d7c80, uev=0x7ff2bc000b50) at main.c:859
859					dm_fail_path(pp->mpp->alias, pp->dev_t);


(gdb) list
854				condlog(0, "%s: path wwid changed from '%s' to '%s'. disallowing", uev->kernel, wwid, pp->wwid);
855				strcpy(pp->wwid, wwid);
856				if (!pp->wwid_changed) {
857					pp->wwid_changed = 1;
858					pp->tick = 1;
859					dm_fail_path(pp->mpp->alias, pp->dev_t);
860				}
861			}
862			else {
863				pp->wwid_changed = 0;

(gdb) p pp
$1 = (struct path *) 0x55ce6e402900
(gdb) p pp->mpp->alias
Cannot access memory at address 0x1c0
(gdb) p pp->mpp->alias
Cannot access memory at address 0x1c0
(gdb) p pp->mpp
$2 = (struct multipath *) 0x0


Seems to be a known bug with disable_changed_wwids

https://listman.redhat.com/archives/dm-devel/2017-March/msg00189.html

Its not patched

I will log a BZ to get it patched, but its due to the disable_changed _wwids being enabled

Best Regards
Red Hat