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Commit01272d9

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Check return values of sensitive system library calls.
PostgreSQL already checked the vast majority of these, missing thishandful that nearly cannot fail. If putenv() failed with ENOMEM inpg_GSS_recvauth(), authentication would proceed with the wrong keytabfile. If strftime() returned zero in cache_locale_time(), using theunspecified buffer contents could lead to information exposure or acrash. Back-patch to 9.0 (all supported versions).Other unchecked calls to these functions, especially those in frontendcode, pose negligible security concern. This patch does not addressthem. Nonetheless, it is always better to check return values whosespecification provides for indicating an error.In passing, fix an off-by-one error in strftime_win32()'s invocation ofWideCharToMultiByte(). Upon retrieving a value of exactly MAX_L10N_DATAbytes, strftime_win32() would overrun the caller's buffer by one byte.MAX_L10N_DATA is chosen to exceed the length of every possible value, sothe vulnerable scenario probably does not arise.Security:CVE-2015-3166
1 parent82b7393 commit01272d9

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2 files changed

+48
-33
lines changed

2 files changed

+48
-33
lines changed

‎src/backend/libpq/auth.c

Lines changed: 4 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -1022,15 +1022,16 @@ pg_GSS_recvauth(Port *port)
10221022
size_tkt_len=strlen(pg_krb_server_keyfile)+14;
10231023
char*kt_path=malloc(kt_len);
10241024

1025-
if (!kt_path)
1025+
if (!kt_path||
1026+
snprintf(kt_path,kt_len,"KRB5_KTNAME=%s",
1027+
pg_krb_server_keyfile)!=kt_len-2||
1028+
putenv(kt_path)!=0)
10261029
{
10271030
ereport(LOG,
10281031
(errcode(ERRCODE_OUT_OF_MEMORY),
10291032
errmsg("out of memory")));
10301033
returnSTATUS_ERROR;
10311034
}
1032-
snprintf(kt_path,kt_len,"KRB5_KTNAME=%s",pg_krb_server_keyfile);
1033-
putenv(kt_path);
10341035
}
10351036
}
10361037

‎src/backend/utils/adt/pg_locale.c

Lines changed: 44 additions & 30 deletions
Original file line numberDiff line numberDiff line change
@@ -558,24 +558,34 @@ PGLC_localeconv(void)
558558
* pg_strftime(), which isn't locale-aware and does not need to be replaced.
559559
*/
560560
staticsize_t
561-
strftime_win32(char*dst,size_tdstlen,constwchar_t*format,conststructtm*tm)
561+
strftime_win32(char*dst,size_tdstlen,
562+
constchar*format,conststructtm*tm)
562563
{
563564
size_tlen;
565+
wchar_twformat[8];/* formats used below need 3 bytes */
564566
wchar_twbuf[MAX_L10N_DATA];
565567
intencoding;
566568

567569
encoding=GetDatabaseEncoding();
568570

569-
len=wcsftime(wbuf,MAX_L10N_DATA,format,tm);
571+
/* get a wchar_t version of the format string */
572+
len=MultiByteToWideChar(CP_UTF8,0,format,-1,
573+
wformat,lengthof(wformat));
574+
if (len==0)
575+
elog(ERROR,"could not convert format string from UTF-8: error code %lu",
576+
GetLastError());
577+
578+
len=wcsftime(wbuf,MAX_L10N_DATA,wformat,tm);
570579
if (len==0)
571580

572581
/*
573-
* strftimecallfailed - return 0 with the contents of dst
574-
* unspecified
582+
* strftime failed, possibly because the result would not fit in
583+
*MAX_L10N_DATA. Return 0 with the contents of dstunspecified.
575584
*/
576585
return0;
577586

578-
len=WideCharToMultiByte(CP_UTF8,0,wbuf,len,dst,dstlen,NULL,NULL);
587+
len=WideCharToMultiByte(CP_UTF8,0,wbuf,len,dst,dstlen-1,
588+
NULL,NULL);
579589
if (len==0)
580590
elog(ERROR,
581591
"could not convert string to UTF-8: error code %lu",GetLastError());
@@ -598,9 +608,33 @@ strftime_win32(char *dst, size_t dstlen, const wchar_t *format, const struct tm
598608
}
599609

600610
/* redefine strftime() */
601-
#definestrftime(a,b,c,d) strftime_win32(a,b,L##c,d)
611+
#definestrftime(a,b,c,d) strftime_win32(a,b,c,d)
602612
#endif/* WIN32 */
603613

614+
/* Subroutine for cache_locale_time(). */
615+
staticvoid
616+
cache_single_time(char**dst,constchar*format,conststructtm*tm)
617+
{
618+
charbuf[MAX_L10N_DATA];
619+
char*ptr;
620+
621+
/*
622+
* MAX_L10N_DATA is sufficient buffer space for every known locale, and
623+
* POSIX defines no strftime() errors. (Buffer space exhaustion is not an
624+
* error.) An implementation might report errors (e.g. ENOMEM) by
625+
* returning 0 (or, less plausibly, a negative value) and setting errno.
626+
* Report errno just in case the implementation did that, but clear it in
627+
* advance of the call so we don't emit a stale, unrelated errno.
628+
*/
629+
errno=0;
630+
if (strftime(buf,MAX_L10N_DATA,format,tm) <=0)
631+
elog(ERROR,"strftime(%s) failed: %m",format);
632+
633+
ptr=MemoryContextStrdup(TopMemoryContext,buf);
634+
if (*dst)
635+
pfree(*dst);
636+
*dst=ptr;
637+
}
604638

605639
/*
606640
* Update the lc_time localization cache variables if needed.
@@ -611,8 +645,6 @@ cache_locale_time(void)
611645
char*save_lc_time;
612646
time_ttimenow;
613647
structtm*timeinfo;
614-
charbuf[MAX_L10N_DATA];
615-
char*ptr;
616648
inti;
617649

618650
#ifdefWIN32
@@ -659,35 +691,17 @@ cache_locale_time(void)
659691
for (i=0;i<7;i++)
660692
{
661693
timeinfo->tm_wday=i;
662-
strftime(buf,MAX_L10N_DATA,"%a",timeinfo);
663-
ptr=MemoryContextStrdup(TopMemoryContext,buf);
664-
if (localized_abbrev_days[i])
665-
pfree(localized_abbrev_days[i]);
666-
localized_abbrev_days[i]=ptr;
667-
668-
strftime(buf,MAX_L10N_DATA,"%A",timeinfo);
669-
ptr=MemoryContextStrdup(TopMemoryContext,buf);
670-
if (localized_full_days[i])
671-
pfree(localized_full_days[i]);
672-
localized_full_days[i]=ptr;
694+
cache_single_time(&localized_abbrev_days[i],"%a",timeinfo);
695+
cache_single_time(&localized_full_days[i],"%A",timeinfo);
673696
}
674697

675698
/* localized months */
676699
for (i=0;i<12;i++)
677700
{
678701
timeinfo->tm_mon=i;
679702
timeinfo->tm_mday=1;/* make sure we don't have invalid date */
680-
strftime(buf,MAX_L10N_DATA,"%b",timeinfo);
681-
ptr=MemoryContextStrdup(TopMemoryContext,buf);
682-
if (localized_abbrev_months[i])
683-
pfree(localized_abbrev_months[i]);
684-
localized_abbrev_months[i]=ptr;
685-
686-
strftime(buf,MAX_L10N_DATA,"%B",timeinfo);
687-
ptr=MemoryContextStrdup(TopMemoryContext,buf);
688-
if (localized_full_months[i])
689-
pfree(localized_full_months[i]);
690-
localized_full_months[i]=ptr;
703+
cache_single_time(&localized_abbrev_months[i],"%b",timeinfo);
704+
cache_single_time(&localized_full_months[i],"%B",timeinfo);
691705
}
692706

693707
/* try to restore internal settings */

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