savecore: unveil bug

[Sebastien Marie]

Hi,

The unveil(2) call for savecore(8) is incomplete. savecore(8) needs to
access to the /bsd to copying it.

Without it, savecore(8) abort the process, and due to karl, the original
kernel is lost.

Without the patch:
------------------
savecore: reboot after panic: pool_do_get: vmmpepl free list modified: page 
0xffffff0187540000; item addr 0xffffff01875400a8; offset 0x38=0xd6adbeef
savecore: system went down at Fri Sep 28 08:07:31 2018
savecore: /bsd: No such file or directory


I was able to successfully extract the dump with the patch (but /bsd
wasn't the right kernel anymore due to reboot).

Thanks.
-- 
Sebastien Marie


Index: savecore.c
===================================================================
RCS file: /cvs/src/sbin/savecore/savecore.c,v
retrieving revision 1.58
diff -u -p -r1.58 savecore.c
--- savecore.c  24 Sep 2018 21:26:38 -0000      1.58
+++ savecore.c  28 Sep 2018 06:47:58 -0000
@@ -175,6 +175,10 @@ main(int argc, char *argv[])
                syslog(LOG_ERR, "unveil: %m");
                exit(1);
        }
+       if (unveil(kernel ? kernel : _PATH_UNIX, "r") == -1) {
+               syslog(LOG_ERR, "unveil: %m");
+               exit(1);
+       }
        if (pledge("stdio rpath wpath cpath", NULL) == -1) {
                syslog(LOG_ERR, "pledge: %m");
                exit(1);