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Fix subshell leak for 4 special variables (re: bd3e2a80)

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The following special variables leaked out of a subshell:
$_, ${.sh.name}, ${.sh.level}, ${.sh.subscript}.
This was due to a faulty optimisation in sh_assignok().
bd3e2a80 fixed that in part, this fixes the rest.

src/cmd/ksh93/sh/subshell.c:
- Simplify sh_assignok() by removing special-casing for these four
  special variables. The 'add' param reverts to a simple boolean.
- The test for a ${ subshare; } was actually wrong. sp->subshare is
  a saved backup value. We must test shp->subshare. (re: a9de50bf)

src/cmd/ksh93/bltins/typeset.c:
- setall(), unall(): Update sh_assignok() calls.

src/cmd/ksh93/tests/variables.sh:
- Regress-test subshell leaks for all special variables.

Closes: #122
This commit is contained in:
Martijn Dekker 2020-09-05 13:57:39 +02:00
parent 00d439605f
commit b3d37b00b0
3 changed files with 19 additions and 12 deletions
Download patch file Download diff file Expand all files Collapse all files

6
src/cmd/ksh93/bltins/typeset.c
View file

@ -688,7 +688,7 @@ static int setall(char **argv,register int flag,Dt_t *troot,struct tdata *tp
* Variables with internal trap/discipline functions (LC_*, LINENO, etc.) need to be
* cloned, as moving them will remove the discipline function.
*/
np=sh_assignok(np,2);
np=sh_assignok(np,1);
}
else
np=sh_assignok(np,0);
@ -800,7 +800,7 @@ static int setall(char **argv,register int flag,Dt_t *troot,struct tdata *tp
if (tp->aflag && (tp->argnum>0 || (curflag!=newflag)))
{
if(shp->subshell)
sh_assignok(np,3);
sh_assignok(np,1);
if(troot!=shp->var_tree)
nv_setattr(np,newflag&~NV_ASSIGN);
else
@ -1285,7 +1285,7 @@ static int unall(int argc, char **argv, register Dt_t *troot, Shell_t* shp)
* Variables with internal trap/discipline functions (LC_*, LINENO, etc.) need to be
* cloned, as moving them will remove the discipline function.
*/
np=sh_assignok(np,2);
np=sh_assignok(np,1);
}
else
np=sh_assignok(np,0);

11
src/cmd/ksh93/sh/subshell.c
View file

@ -233,10 +233,6 @@ int nv_subsaved(register Namval_t *np)
*
* add == 0: Move the node pointer from the parent shell to the current virtual subshell.
* add == 1: Create a copy of the node pointer in the current virtual subshell.
* add == 2: This will create a copy of the node pointer like 1, but it will disable the
* optimization for ${.sh.level}.
* add == 3: This is like 1, but it will never skip the following variables:
* ${.sh.level}, $_, ${.sh.subscript} and ${.sh.name}.
*/
Namval_t *sh_assignok(register Namval_t *np,int add)
{
@ -248,11 +244,8 @@ Namval_t *sh_assignok(register Namval_t *np,int add)
Namval_t *mpnext;
Namarr_t *ap;
unsigned int save;
/* don't bother to save if in a ${ subshare; } */
if(sp->subshare)
return(np);
/* don't bother with this */
if(!sp->shpwd || (add != 3 && ((add != 2 && np==SH_LEVELNOD) || np==L_ARGNOD || np==SH_SUBSCRNOD || np==SH_NAMENOD)))
/* don't save if told not to (see nv_restore()) or if we're in a ${ subshare; } */
if(!sp->shpwd || shp->subshare)
return(np);
if((ap=nv_arrayptr(np)) && (mp=nv_opensub(np)))
{

14
src/cmd/ksh93/tests/variables.sh
View file

@ -1011,6 +1011,20 @@ $SHELL -c '
e=$?
((e == 1)) || err_exit "Failure in making one or more special variables readonly in a subshell (exit status $e)"
# ... subshell leak test
$SHELL -c '
errors=0
for var
do if eval "($var=bug); [[ \${$var} == bug ]]" 2>/dev/null
then echo " $0: special variable $var leaks out of subshell" >&2
let errors++
fi
done
exit $((errors + 1))
' subshell_leak_test "$@"
e=$?
((e == 1)) || err_exit "One or more special variables leak out of a subshell (exit status $e)"
# ======
# ${.sh.pid} should be the forked subshell's PID
(