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Commit642b0b6

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Don't leak malloc'd strings when a GUC setting is rejected.
Because guc.c prefers to keep all its string values in malloc'dnot palloc'd storage, it has to be more careful than usual toavoid leaks. Error exits out of string GUC hook checks failedto clear the proposed value string, and error exits out ofProcessGUCArray() failed to clear the malloc'd results ofParseLongOption().Found via valgrind testing.This problem is ancient, so back-patch to all supported branches.Discussion:https://postgr.es/m/3816764.1616104288@sss.pgh.pa.us
1 parenteba9395 commit642b0b6

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1 file changed

+47
-24
lines changed
  • src/backend/utils/misc

1 file changed

+47
-24
lines changed

‎src/backend/utils/misc/guc.c

Lines changed: 47 additions & 24 deletions
Original file line numberDiff line numberDiff line change
@@ -10591,6 +10591,8 @@ ProcessGUCArray(ArrayType *array,
1059110591
char*s;
1059210592
char*name;
1059310593
char*value;
10594+
char*namecopy;
10595+
char*valuecopy;
1059410596

1059510597
d=array_ref(array,1,&i,
1059610598
-1/* varlenarray */ ,
@@ -10615,13 +10617,18 @@ ProcessGUCArray(ArrayType *array,
1061510617
continue;
1061610618
}
1061710619

10618-
(void)set_config_option(name,value,
10620+
/* free malloc'd strings immediately to avoid leak upon error */
10621+
namecopy=pstrdup(name);
10622+
free(name);
10623+
valuecopy=pstrdup(value);
10624+
free(value);
10625+
10626+
(void)set_config_option(namecopy,valuecopy,
1061910627
context,source,
1062010628
action, true,0, false);
1062110629

10622-
free(name);
10623-
if (value)
10624-
free(value);
10630+
pfree(namecopy);
10631+
pfree(valuecopy);
1062510632
pfree(s);
1062610633
}
1062710634
}
@@ -11053,34 +11060,50 @@ static bool
1105311060
call_string_check_hook(structconfig_string*conf,char**newval,void**extra,
1105411061
GucSourcesource,intelevel)
1105511062
{
11063+
volatileboolresult= true;
11064+
1105611065
/* Quick success if no hook */
1105711066
if (!conf->check_hook)
1105811067
return true;
1105911068

11060-
/* Reset variables that might be set by hook */
11061-
GUC_check_errcode_value=ERRCODE_INVALID_PARAMETER_VALUE;
11062-
GUC_check_errmsg_string=NULL;
11063-
GUC_check_errdetail_string=NULL;
11064-
GUC_check_errhint_string=NULL;
11069+
/*
11070+
* If elevel is ERROR, or if the check_hook itself throws an elog
11071+
* (undesirable, but not always avoidable), make sure we don't leak the
11072+
* already-malloc'd newval string.
11073+
*/
11074+
PG_TRY();
11075+
{
11076+
/* Reset variables that might be set by hook */
11077+
GUC_check_errcode_value=ERRCODE_INVALID_PARAMETER_VALUE;
11078+
GUC_check_errmsg_string=NULL;
11079+
GUC_check_errdetail_string=NULL;
11080+
GUC_check_errhint_string=NULL;
1106511081

11066-
if (!conf->check_hook(newval,extra,source))
11082+
if (!conf->check_hook(newval,extra,source))
11083+
{
11084+
ereport(elevel,
11085+
(errcode(GUC_check_errcode_value),
11086+
GUC_check_errmsg_string ?
11087+
errmsg_internal("%s",GUC_check_errmsg_string) :
11088+
errmsg("invalid value for parameter \"%s\": \"%s\"",
11089+
conf->gen.name,*newval ?*newval :""),
11090+
GUC_check_errdetail_string ?
11091+
errdetail_internal("%s",GUC_check_errdetail_string) :0,
11092+
GUC_check_errhint_string ?
11093+
errhint("%s",GUC_check_errhint_string) :0));
11094+
/* Flush any strings created in ErrorContext */
11095+
FlushErrorState();
11096+
result= false;
11097+
}
11098+
}
11099+
PG_CATCH();
1106711100
{
11068-
ereport(elevel,
11069-
(errcode(GUC_check_errcode_value),
11070-
GUC_check_errmsg_string ?
11071-
errmsg_internal("%s",GUC_check_errmsg_string) :
11072-
errmsg("invalid value for parameter \"%s\": \"%s\"",
11073-
conf->gen.name,*newval ?*newval :""),
11074-
GUC_check_errdetail_string ?
11075-
errdetail_internal("%s",GUC_check_errdetail_string) :0,
11076-
GUC_check_errhint_string ?
11077-
errhint("%s",GUC_check_errhint_string) :0));
11078-
/* Flush any strings created in ErrorContext */
11079-
FlushErrorState();
11080-
return false;
11101+
free(*newval);
11102+
PG_RE_THROW();
1108111103
}
11104+
PG_END_TRY();
1108211105

11083-
returntrue;
11106+
returnresult;
1108411107
}
1108511108

1108611109
staticbool

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