Revert error-throwing wrappers for the printf family of functions.

This reverts commit 16304a0134, except
for its changes in src/port/snprintf.c; as well as commit
cac18a76bb which is no longer needed.

Fujii Masao reported that the previous commit caused failures in psql on
OS X, since if one exits the pager program early while viewing a query
result, psql sees an EPIPE error from fprintf --- and the wrapper function
thought that was reason to panic.  (It's a bit surprising that the same
does not happen on Linux.)  Further discussion among the security list
concluded that the risk of other such failures was far too great, and
that the one-size-fits-all approach to error handling embodied in the
previous patch is unlikely to be workable.

This leaves us again exposed to the possibility of the type of failure
envisioned in CVE-2015-3166.  However, that failure mode is strictly
hypothetical at this point: there is no concrete reason to believe that
an attacker could trigger information disclosure through the supposed
mechanism.  In the first place, the attack surface is fairly limited,
since so much of what the backend does with format strings goes through
stringinfo.c or psprintf(), and those already had adequate defenses.
In the second place, even granting that an unprivileged attacker could
control the occurrence of ENOMEM with some precision, it's a stretch to
believe that he could induce it just where the target buffer contains some
valuable information.  So we concluded that the risk of non-hypothetical
problems induced by the patch greatly outweighs the security risks.
We will therefore revert, and instead undertake closer analysis to
identify specific calls that may need hardening, rather than attempt a
universal solution.

We have kept the portion of the previous patch that improved snprintf.c's
handling of errors when it calls the platform's sprintf().  That seems to
be an unalloyed improvement.

Security: CVE-2015-3166
This commit is contained in:
Tom Lane 2015-05-19 18:14:52 -04:00
parent 9bc77c4519
commit 0c071936e9
16 changed files with 53 additions and 251 deletions

View File

@ -126,11 +126,12 @@ extern unsigned char pg_tolower(unsigned char ch);
extern unsigned char pg_ascii_toupper(unsigned char ch);
extern unsigned char pg_ascii_tolower(unsigned char ch);
#ifdef USE_REPL_SNPRINTF
/*
* Capture macro-compatible calls to printf() and friends, and redirect them
* to wrappers that throw errors in lieu of reporting failure in a return
* value. Versions of libintl >= 0.13 similarly redirect to versions that
* understand the %$ format, so disable libintl macros first.
* Versions of libintl >= 0.13 try to replace printf() and friends with
* macros to their own versions that understand the %$ format. We do the
* same, so disable their macros, if they exist.
*/
#ifdef vsnprintf
#undef vsnprintf
@ -138,9 +139,6 @@ extern unsigned char pg_ascii_tolower(unsigned char ch);
#ifdef snprintf
#undef snprintf
#endif
#ifdef vsprintf
#undef vsprintf
#endif
#ifdef sprintf
#undef sprintf
#endif
@ -154,63 +152,33 @@ extern unsigned char pg_ascii_tolower(unsigned char ch);
#undef printf
#endif
extern int
vsnprintf_throw_on_fail(char *str, size_t count, const char *fmt, va_list args)
pg_attribute_printf(3, 0);
extern int
snprintf_throw_on_fail(char *str, size_t count, const char *fmt,...)
pg_attribute_printf(3, 4);
extern int
vsprintf_throw_on_fail(char *str, const char *fmt, va_list args)
pg_attribute_printf(2, 0);
extern int
sprintf_throw_on_fail(char *str, const char *fmt,...)
pg_attribute_printf(2, 3);
extern int
vfprintf_throw_on_fail(FILE *stream, const char *fmt, va_list args)
pg_attribute_printf(2, 0);
extern int
fprintf_throw_on_fail(FILE *stream, const char *fmt,...)
pg_attribute_printf(2, 3);
extern int
printf_throw_on_fail(const char *fmt,...)
pg_attribute_printf(1, 2);
/*
* The GCC-specific code below prevents the pg_attribute_printf above from
* being replaced, and this is required because gcc doesn't know anything
* about printf_throw_on_fail.
*/
#ifdef __GNUC__
#define vsnprintf(...) vsnprintf_throw_on_fail(__VA_ARGS__)
#define snprintf(...) snprintf_throw_on_fail(__VA_ARGS__)
#define vsprintf(...) vsprintf_throw_on_fail(__VA_ARGS__)
#define sprintf(...) sprintf_throw_on_fail(__VA_ARGS__)
#define vfprintf(...) vfprintf_throw_on_fail(__VA_ARGS__)
#define fprintf(...) fprintf_throw_on_fail(__VA_ARGS__)
#define printf(...) printf_throw_on_fail(__VA_ARGS__)
#else
#define vsnprintf vsnprintf_throw_on_fail
#define snprintf snprintf_throw_on_fail
#define vsprintf vsprintf_throw_on_fail
#define sprintf sprintf_throw_on_fail
#define vfprintf vfprintf_throw_on_fail
#define fprintf fprintf_throw_on_fail
#define printf printf_throw_on_fail
#endif
#ifdef USE_REPL_SNPRINTF
/* Code outside syswrap.c should not call these. */
extern int pg_vsnprintf(char *str, size_t count, const char *fmt, va_list args);
extern int pg_snprintf(char *str, size_t count, const char *fmt,...) pg_attribute_printf(3, 4);
extern int pg_vsprintf(char *str, const char *fmt, va_list args);
extern int pg_sprintf(char *str, const char *fmt,...) pg_attribute_printf(2, 3);
extern int pg_vfprintf(FILE *stream, const char *fmt, va_list args);
extern int pg_fprintf(FILE *stream, const char *fmt,...) pg_attribute_printf(2, 3);
extern int pg_printf(const char *fmt,...) pg_attribute_printf(1, 2);
/*
* The GCC-specific code below prevents the pg_attribute_printf above from
* being replaced, and this is required because gcc doesn't know anything
* about pg_printf.
*/
#ifdef __GNUC__
#define vsnprintf(...) pg_vsnprintf(__VA_ARGS__)
#define snprintf(...) pg_snprintf(__VA_ARGS__)
#define sprintf(...) pg_sprintf(__VA_ARGS__)
#define vfprintf(...) pg_vfprintf(__VA_ARGS__)
#define fprintf(...) pg_fprintf(__VA_ARGS__)
#define printf(...) pg_printf(__VA_ARGS__)
#else
#define vsnprintf pg_vsnprintf
#define snprintf pg_snprintf
#define sprintf pg_sprintf
#define vfprintf pg_vfprintf
#define fprintf pg_fprintf
#define printf pg_printf
#endif
#endif /* USE_REPL_SNPRINTF */
#if defined(WIN32)

View File

@ -48,7 +48,6 @@ submake-pgtypeslib:
# Shared library stuff
include $(top_srcdir)/src/Makefile.shlib
# XXX This library uses no symbols from snprintf.c.
snprintf.c: % : $(top_srcdir)/src/port/%
rm -f $@ && $(LN_S) $< .

View File

@ -5,7 +5,6 @@
/pgstrcasecmp.c
/snprintf.c
/strlcpy.c
/syswrap.c
/thread.c
/win32setlocale.c
/isinf.c

View File

@ -26,7 +26,7 @@ override CFLAGS += $(PTHREAD_CFLAGS)
LIBS := $(filter-out -lpgport, $(LIBS))
OBJS= execute.o typename.o descriptor.o sqlda.o data.o error.o prepare.o memory.o \
connect.o misc.o path.o pgstrcasecmp.o syswrap.o \
connect.o misc.o path.o pgstrcasecmp.o \
$(filter snprintf.o strlcpy.o win32setlocale.o isinf.o, $(LIBOBJS)) $(WIN32RES)
# thread.c is needed only for non-WIN32 implementation of path.c
@ -55,7 +55,7 @@ include $(top_srcdir)/src/Makefile.shlib
# necessarily use the same object files as the backend uses. Instead,
# symlink the source files in here and build our own object file.
path.c pgstrcasecmp.c snprintf.c strlcpy.c syswrap.c thread.c win32setlocale.c isinf.c: % : $(top_srcdir)/src/port/%
path.c pgstrcasecmp.c snprintf.c strlcpy.c thread.c win32setlocale.c isinf.c: % : $(top_srcdir)/src/port/%
rm -f $@ && $(LN_S) $< .
misc.o: misc.c $(top_builddir)/src/port/pg_config_paths.h
@ -72,6 +72,6 @@ uninstall: uninstall-lib
clean distclean: clean-lib
rm -f $(OBJS)
rm -f path.c pgstrcasecmp.c snprintf.c strlcpy.c syswrap.c thread.c win32setlocale.c isinf.c
rm -f path.c pgstrcasecmp.c snprintf.c strlcpy.c thread.c win32setlocale.c isinf.c
maintainer-clean: distclean maintainer-clean-lib

View File

@ -4,4 +4,3 @@
/pgstrcasecmp.c
/rint.c
/snprintf.c
/syswrap.c

View File

@ -30,7 +30,7 @@ SHLIB_LINK += -lm
SHLIB_EXPORTS = exports.txt
OBJS= numeric.o datetime.o common.o dt_common.o timestamp.o interval.o \
pgstrcasecmp.o syswrap.o \
pgstrcasecmp.o \
$(filter rint.o snprintf.o, $(LIBOBJS)) $(WIN32RES)
all: all-lib
@ -43,7 +43,7 @@ include $(top_srcdir)/src/Makefile.shlib
# necessarily use the same object files as the backend uses. Instead,
# symlink the source files in here and build our own object file.
pgstrcasecmp.c rint.c snprintf.c syswrap.c: % : $(top_srcdir)/src/port/%
pgstrcasecmp.c rint.c snprintf.c: % : $(top_srcdir)/src/port/%
rm -f $@ && $(LN_S) $< .
install: all installdirs install-lib
@ -53,6 +53,6 @@ installdirs: installdirs-lib
uninstall: uninstall-lib
clean distclean: clean-lib
rm -f $(OBJS) pgstrcasecmp.c rint.c snprintf.c syswrap.c
rm -f $(OBJS) pgstrcasecmp.c rint.c snprintf.c
maintainer-clean: distclean maintainer-clean-lib

View File

@ -13,7 +13,6 @@
/strerror.c
/strlcpy.c
/system.c
/syswrap.c
/thread.c
/win32error.c
/win32setlocale.c

View File

@ -36,7 +36,7 @@ OBJS= fe-auth.o fe-connect.o fe-exec.o fe-misc.o fe-print.o fe-lobj.o \
libpq-events.o
# libpgport C files we always use
OBJS += chklocale.o inet_net_ntop.o noblock.o pgstrcasecmp.o pqsignal.o \
syswrap.o thread.o
thread.o
# libpgport C files that are needed if identified by configure
OBJS += $(filter crypt.o getaddrinfo.o getpeereid.o inet_aton.o open.o system.o snprintf.o strerror.o strlcpy.o win32error.o win32setlocale.o, $(LIBOBJS))
# backend/libpq
@ -93,7 +93,7 @@ backend_src = $(top_srcdir)/src/backend
# For some libpgport modules, this only happens if configure decides
# the module is needed (see filter hack in OBJS, above).
chklocale.c crypt.c getaddrinfo.c getpeereid.c inet_aton.c inet_net_ntop.c noblock.c open.c system.c pgsleep.c pgstrcasecmp.c pqsignal.c snprintf.c strerror.c strlcpy.c syswrap.c thread.c win32error.c win32setlocale.c: % : $(top_srcdir)/src/port/%
chklocale.c crypt.c getaddrinfo.c getpeereid.c inet_aton.c inet_net_ntop.c noblock.c open.c system.c pgsleep.c pgstrcasecmp.c pqsignal.c snprintf.c strerror.c strlcpy.c thread.c win32error.c win32setlocale.c: % : $(top_srcdir)/src/port/%
rm -f $@ && $(LN_S) $< .
ip.c md5.c: % : $(backend_src)/libpq/%
@ -145,7 +145,7 @@ clean distclean: clean-lib
# Might be left over from a Win32 client-only build
rm -f pg_config_paths.h
rm -f inet_net_ntop.c noblock.c pgstrcasecmp.c pqsignal.c thread.c
rm -f chklocale.c crypt.c getaddrinfo.c getpeereid.c inet_aton.c open.c system.c snprintf.c strerror.c strlcpy.c syswrap.c win32error.c win32setlocale.c
rm -f chklocale.c crypt.c getaddrinfo.c getpeereid.c inet_aton.c open.c system.c snprintf.c strerror.c strlcpy.c win32error.c win32setlocale.c
rm -f pgsleep.c
rm -f md5.c ip.c
rm -f encnames.c wchar.c

View File

@ -107,7 +107,6 @@ CLEAN :
-@erase "$(INTDIR)\pgsleep.obj"
-@erase "$(INTDIR)\open.obj"
-@erase "$(INTDIR)\system.obj"
-@erase "$(INTDIR)\syswrap.obj"
-@erase "$(INTDIR)\win32error.obj"
-@erase "$(OUTDIR)\$(OUTFILENAME).lib"
-@erase "$(OUTDIR)\$(OUTFILENAME)dll.lib"
@ -152,7 +151,6 @@ LIB32_OBJS= \
"$(INTDIR)\pgsleep.obj" \
"$(INTDIR)\open.obj" \
"$(INTDIR)\system.obj" \
"$(INTDIR)\syswrap.obj" \
"$(INTDIR)\win32error.obj" \
"$(INTDIR)\pthread-win32.obj"
@ -304,11 +302,6 @@ LINK32_FLAGS = -Gn -L$(BCB)\lib;$(INTDIR); -x -Tpd -v
$(CPP_PROJ) /I"." ..\..\port\system.c
<<
"$(INTDIR)\syswrap.obj" : ..\..\port\syswrap.c
$(CPP) @<<
$(CPP_PROJ) ..\..\port\syswrap.c
<<
"$(INTDIR)\win32error.obj" : ..\..\port\win32error.c
$(CPP) @<<
$(CPP_PROJ) /I"." ..\..\port\win32error.c

View File

@ -114,7 +114,6 @@ CLEAN :
-@erase "$(INTDIR)\pgsleep.obj"
-@erase "$(INTDIR)\open.obj"
-@erase "$(INTDIR)\system.obj"
-@erase "$(INTDIR)\syswrap.obj"
-@erase "$(INTDIR)\win32error.obj"
-@erase "$(INTDIR)\win32setlocale.obj"
-@erase "$(OUTDIR)\$(OUTFILENAME).lib"
@ -165,7 +164,6 @@ LIB32_OBJS= \
"$(INTDIR)\pgsleep.obj" \
"$(INTDIR)\open.obj" \
"$(INTDIR)\system.obj" \
"$(INTDIR)\syswrap.obj" \
"$(INTDIR)\win32error.obj" \
"$(INTDIR)\win32setlocale.obj" \
"$(INTDIR)\pthread-win32.obj"
@ -350,11 +348,6 @@ LINK32_OBJS= \
$(CPP_PROJ) /I"." ..\..\port\system.c
<<
"$(INTDIR)\syswrap.obj" : ..\..\port\syswrap.c
$(CPP) @<<
$(CPP_PROJ) ..\..\port\syswrap.c
<<
"$(INTDIR)\win32error.obj" : ..\..\port\win32error.c
$(CPP) @<<
$(CPP_PROJ) /I"." ..\..\port\win32error.c

View File

@ -37,8 +37,10 @@
* So we undefine them here and redefine them after it's done its dirty deed.
*/
#ifdef USE_REPL_SNPRINTF
#undef snprintf
#undef vsnprintf
#endif
/* required for perl API */
@ -47,6 +49,7 @@
#include "XSUB.h"
/* put back our snprintf and vsnprintf */
#ifdef USE_REPL_SNPRINTF
#ifdef snprintf
#undef snprintf
#endif
@ -54,12 +57,13 @@
#undef vsnprintf
#endif
#ifdef __GNUC__
#define vsnprintf(...) vsnprintf_throw_on_fail(__VA_ARGS__)
#define snprintf(...) snprintf_throw_on_fail(__VA_ARGS__)
#define vsnprintf(...) pg_vsnprintf(__VA_ARGS__)
#define snprintf(...) pg_snprintf(__VA_ARGS__)
#else
#define vsnprintf vsnprintf_throw_on_fail
#define snprintf snprintf_throw_on_fail
#define vsnprintf pg_vsnprintf
#define snprintf pg_snprintf
#endif /* __GNUC__ */
#endif /* USE_REPL_SNPRINTF */
/* perl version and platform portability */
#define NEED_eval_pv

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@ -35,8 +35,10 @@
* So we undefine them here and redefine them after it's done its dirty deed.
*/
#ifdef USE_REPL_SNPRINTF
#undef snprintf
#undef vsnprintf
#endif
#if defined(_MSC_VER) && defined(_DEBUG)
/* Python uses #pragma to bring in a non-default libpython on VC++ if
@ -123,6 +125,7 @@ typedef int Py_ssize_t;
#include <eval.h>
/* put back our snprintf and vsnprintf */
#ifdef USE_REPL_SNPRINTF
#ifdef snprintf
#undef snprintf
#endif
@ -130,12 +133,13 @@ typedef int Py_ssize_t;
#undef vsnprintf
#endif
#ifdef __GNUC__
#define vsnprintf(...) vsnprintf_throw_on_fail(__VA_ARGS__)
#define snprintf(...) snprintf_throw_on_fail(__VA_ARGS__)
#define vsnprintf(...) pg_vsnprintf(__VA_ARGS__)
#define snprintf(...) pg_snprintf(__VA_ARGS__)
#else
#define vsnprintf vsnprintf_throw_on_fail
#define snprintf snprintf_throw_on_fail
#define vsnprintf pg_vsnprintf
#define snprintf pg_snprintf
#endif /* __GNUC__ */
#endif /* USE_REPL_SNPRINTF */
/*
* Used throughout, and also by the Python 2/3 porting layer, so it's easier to

View File

@ -33,7 +33,7 @@ LIBS += $(PTHREAD_LIBS)
OBJS = $(LIBOBJS) $(PG_CRC32C_OBJS) chklocale.o erand48.o inet_net_ntop.o \
noblock.o path.o pgcheckdir.o pgmkdirp.o pgsleep.o \
pgstrcasecmp.o pqsignal.o \
qsort.o qsort_arg.o quotes.o sprompt.o syswrap.o tar.o thread.o
qsort.o qsort_arg.o quotes.o sprompt.o tar.o thread.o
# foo_srv.o and foo.o are both built from foo.c, but only foo.o has -DFRONTEND
OBJS_SRV = $(OBJS:%.o=%_srv.o)

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@ -99,7 +99,6 @@
/* Prevent recursion */
#undef vsnprintf
#undef snprintf
#undef vsprintf
#undef sprintf
#undef vfprintf
#undef fprintf
@ -176,7 +175,7 @@ pg_snprintf(char *str, size_t count, const char *fmt,...)
return len;
}
int
static int
pg_vsprintf(char *str, const char *fmt, va_list args)
{
PrintfTarget target;

View File

@ -1,155 +0,0 @@
/*-------------------------------------------------------------------------
*
* syswrap.c
* error-throwing wrappers around POSIX functions that rarely fail
*
* Portions Copyright (c) 1996-2015, PostgreSQL Global Development Group
*
*
* IDENTIFICATION
* src/port/syswrap.c
*
*-------------------------------------------------------------------------
*/
#ifndef FRONTEND
#include "postgres.h"
#else
#include "postgres_fe.h"
#endif
/* Prevent recursion */
#undef vsnprintf
#undef snprintf
#undef vsprintf
#undef sprintf
#undef vfprintf
#undef fprintf
#undef printf
/* When the libc primitives are lacking, use our own. */
#ifdef USE_REPL_SNPRINTF
#ifdef __GNUC__
#define vsnprintf(...) pg_vsnprintf(__VA_ARGS__)
#define snprintf(...) pg_snprintf(__VA_ARGS__)
#define vsprintf(...) pg_vsprintf(__VA_ARGS__)
#define sprintf(...) pg_sprintf(__VA_ARGS__)
#define vfprintf(...) pg_vfprintf(__VA_ARGS__)
#define fprintf(...) pg_fprintf(__VA_ARGS__)
#define printf(...) pg_printf(__VA_ARGS__)
#else
#define vsnprintf pg_vsnprintf
#define snprintf pg_snprintf
#define vsprintf pg_vsprintf
#define sprintf pg_sprintf
#define vfprintf pg_vfprintf
#define fprintf pg_fprintf
#define printf pg_printf
#endif
#endif /* USE_REPL_SNPRINTF */
/*
* We abort() in the frontend, rather than exit(), because libpq in particular
* has no business calling exit(). These failures had better be rare.
*/
#ifdef FRONTEND
#define LIB_ERR(func) \
do { \
int discard = fprintf(stderr, "%s failed: %s\n", func, strerror(errno)); \
(void) discard; \
abort(); \
} while (0)
#else
#define LIB_ERR(func) elog(ERROR, "%s failed: %m", func)
#endif
int
vsnprintf_throw_on_fail(char *str, size_t count, const char *fmt, va_list args)
{
int save_errno;
int ret;
/*
* On HP-UX B.11.31, a call that truncates output returns -1 without
* setting errno. (SUSv2 allowed this until the approval of Base Working
* Group Resolution BWG98-006.) We could avoid the save and restore of
* errno on most platforms.
*/
save_errno = errno;
errno = 0;
ret = vsnprintf(str, count, fmt, args);
if (ret < 0 && errno != 0)
LIB_ERR("vsnprintf");
errno = save_errno;
return ret;
}
int
snprintf_throw_on_fail(char *str, size_t count, const char *fmt,...)
{
int ret;
va_list args;
va_start(args, fmt);
ret = vsnprintf_throw_on_fail(str, count, fmt, args);
va_end(args);
return ret;
}
int
vsprintf_throw_on_fail(char *str, const char *fmt, va_list args)
{
int ret;
ret = vsprintf(str, fmt, args);
if (ret < 0)
LIB_ERR("vsprintf");
return ret;
}
int
sprintf_throw_on_fail(char *str, const char *fmt,...)
{
int ret;
va_list args;
va_start(args, fmt);
ret = vsprintf_throw_on_fail(str, fmt, args);
va_end(args);
return ret;
}
int
vfprintf_throw_on_fail(FILE *stream, const char *fmt, va_list args)
{
int ret;
ret = vfprintf(stream, fmt, args);
if (ret < 0)
LIB_ERR("vfprintf");
return ret;
}
int
fprintf_throw_on_fail(FILE *stream, const char *fmt,...)
{
int ret;
va_list args;
va_start(args, fmt);
ret = vfprintf_throw_on_fail(stream, fmt, args);
va_end(args);
return ret;
}
int
printf_throw_on_fail(const char *fmt,...)
{
int ret;
va_list args;
va_start(args, fmt);
ret = vfprintf_throw_on_fail(stdout, fmt, args);
va_end(args);
return ret;
}

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@ -91,7 +91,7 @@ sub mkvcbuild
erand48.c snprintf.c strlcat.c strlcpy.c dirmod.c noblock.c path.c
pgcheckdir.c pgmkdirp.c pgsleep.c pgstrcasecmp.c pqsignal.c
mkdtemp.c qsort.c qsort_arg.c quotes.c system.c
sprompt.c syswrap.c tar.c thread.c getopt.c getopt_long.c dirent.c
sprompt.c tar.c thread.c getopt.c getopt_long.c dirent.c
win32env.c win32error.c win32setlocale.c);
push(@pgportfiles, 'rint.c') if ($vsVersion < '12.00');