[ast-developers] Bug in ksh command 'cd' ?

[Vladimir Marek]

Hi,

I'm not an ksh developer, so sorry if I got some things wrong.

Recently on Solaris I found out that this command cores:

$ /usr/bin/cd a b
Segmentation Fault (core dumped)

$ pstack core
core 'core' of 10186: /usr/bin/cd a b
000000000047c1a8 sh_substitute () + 30
000000000049d853 b_cd () + 1bb
000000000048bc3b sh_exec () + 34b7
00000000004898e5 sh_exec () + 1161
000000000048a557 sh_exec () + 1dd3
0000000000487b53 sh_eval () + 263
0000000000431142 sh_trap () + 1f2
000000000042f50b main () + 27f
000000000042f12c ???????? ()


After some digging I found out that the cd surprisingly(?) comes from
ksh sources. After a bit of debugging it turns out that this patch seems to fix
the issue:

--- a/src/cmd/ksh93/bltins/cd_pwd.c 2013-10-31 16:18:43.904039613 +0100
+++ b/src/cmd/ksh93/bltins/cd_pwd.c 2013-10-31 16:18:14.980499662 +0100
@@ -81,7 +81,7 @@
dir = argv[0];
if(error_info.errors>0 || argc >2)
errormsg(SH_DICT,ERROR_usage(2),"%s",optusage((char*)0));
- oldpwd = (char*)shp->pwd;
+ oldpwd = path_pwd(shp,0)
opwdnod = (shp->subshell?sh_assignok(OLDPWDNOD,1):OLDPWDNOD);
pwdnod = (shp->subshell?sh_assignok(PWDNOD,1):PWDNOD);
if(argc==2)


The problem was that shp->pwd was 0. Looking around the file it seems
that 'the' way of getting current directory is calling path_pwd and thus
this diff. I wasn't able to find any public repository containing
sources to check whether the issue is fixed already in development
branch or not.

I do have two questions.

a) Is the fix correct?
b) If this issue is not already fixed in your source tree, would you
mind including the fix there?

Thank you