Clean up PL_strtab hash with NULL in perl_destruct

ekotik · antirs · commit 2345cf031a0c · 2025-06-13T05:43:42.000Z
As it's not required to pre-allocate PL_strtab hash before perl_construct() and PL_strtab is not initialized with NULL by default, SIGSEGV could happen in certain circumstances. Particularly, when application links libperl and runs perl several times. After the first run PL_strtab remains unitialized in perl_construct() as it was not cleared in perl_destruct() and it contains garbage and the next initialization in perl_construct() is skipped because !PL_strtab check is skipped. See also: c82f488 (Allow custom PL_strtab hash in perl_construct.)
diff --git a/AUTHORS b/AUTHORS
@@ -1223,6 +1223,7 @@ Robert Spier                   <rspier@pobox.com>
 Roberto C. Sanchez             <roberto@connexer.com>
 Robin Barker                   <RMBarker@cpan.org>
 Robin Houston                  <robin@cpan.org>
+Robin Ragged                   <robin.ragged@paranoici.org>
 Rocco Caputo                   <troc@netrus.net>
 Roderick Schertler             <roderick@argon.org>
 Rodger Anderson                <rodger@boi.hp.com>
diff --git a/perl.c b/perl.c
@@ -1389,6 +1389,7 @@ perl_destruct(pTHXx)
         HvTOTALKEYS(PL_strtab) = 0;
     }
     SvREFCNT_dec(PL_strtab);
+    PL_strtab = NULL;
 
 #ifdef USE_ITHREADS
     /* free the pointer tables used for cloning */

-Original file line number
+Diff line change
 Roberto C. Sanchez             <[email protected]>
 Robin Barker                   <[email protected]>
 Robin Houston                  <[email protected]>
 +Robin Ragged                   <[email protected]>
 Rocco Caputo                   <[email protected]>
 Roderick Schertler             <[email protected]>
 Rodger Anderson                <[email protected]>
Original file line number	Diff line number	Diff line change
`@@ -1389,6 +1389,7 @@ perl_destruct(pTHXx)`
`1389`	`1389`	`HvTOTALKEYS(PL_strtab) = 0;`
`1390`	`1390`	`}`
`1391`	`1391`	`SvREFCNT_dec(PL_strtab);`
	`1392`	`+ PL_strtab = NULL;`
`1392`	`1393`
`1393`	`1394`	`#ifdef USE_ITHREADS`
`1394`	`1395`	`/* free the pointer tables used for cloning */`