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

All known standard library implementations of these functions can fail
with ENOMEM.  A caller neglecting to check for failure would experience
missing output, information exposure, or a crash.  Check return values
within wrappers and code, currently just snprintf.c, that bypasses the
wrappers.  The wrappers do not return after an error, so their callers
need not check.  Back-patch to 9.0 (all supported versions).

Popular free software standard library implementations do take pains to
bypass malloc() in simple cases, but they risk ENOMEM for floating point
numbers, positional arguments, large field widths, and large precisions.
No specification demands such caution, so this commit regards every call
to a printf family function as a potential threat.

Injecting the wrappers implicitly is a compromise between patch scope
and design goals.  I would prefer to edit each call site to name a
wrapper explicitly.  libpq and the ECPG libraries would, ideally, convey
errors to the caller rather than abort().  All that would be painfully
invasive for a back-patched security fix, hence this compromise.

Security: CVE-2015-3166

5 files changed, 9 insertions, 6 deletions

diff --git a/src/interfaces/ecpg/compatlib/Makefile b/src/interfaces/ecpg/compatlib/Makefile
index ed52bff01ed..fcbddbf5812 100644
--- a/src/interfaces/ecpg/compatlib/Makefile
+++ b/src/interfaces/ecpg/compatlib/Makefile
@@ -48,6 +48,7 @@ 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) $< .
 
diff --git a/src/interfaces/ecpg/ecpglib/.gitignore b/src/interfaces/ecpg/ecpglib/.gitignore
index 8ef6401dd0e..c28ac74fa9a 100644
--- a/src/interfaces/ecpg/ecpglib/.gitignore
+++ b/src/interfaces/ecpg/ecpglib/.gitignore
@@ -5,6 +5,7 @@
 /pgstrcasecmp.c
 /snprintf.c
 /strlcpy.c
+/syswrap.c
 /thread.c
 /win32setlocale.c
 /isinf.c
diff --git a/src/interfaces/ecpg/ecpglib/Makefile b/src/interfaces/ecpg/ecpglib/Makefile
index a4ec8c80e6a..35791168d91 100644
--- a/src/interfaces/ecpg/ecpglib/Makefile
+++ b/src/interfaces/ecpg/ecpglib/Makefile
@@ -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 \
+	connect.o misc.o path.o pgstrcasecmp.o syswrap.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 thread.c win32setlocale.c isinf.c: % : $(top_srcdir)/src/port/%
+path.c pgstrcasecmp.c snprintf.c strlcpy.c syswrap.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 thread.c win32setlocale.c isinf.c
+	rm -f path.c pgstrcasecmp.c snprintf.c strlcpy.c syswrap.c thread.c win32setlocale.c isinf.c
 
 maintainer-clean: distclean maintainer-clean-lib
diff --git a/src/interfaces/ecpg/pgtypeslib/.gitignore b/src/interfaces/ecpg/pgtypeslib/.gitignore
index fbcd68d7d3e..e33c94d81f6 100644
--- a/src/interfaces/ecpg/pgtypeslib/.gitignore
+++ b/src/interfaces/ecpg/pgtypeslib/.gitignore
@@ -4,3 +4,4 @@
 /pgstrcasecmp.c
 /rint.c
 /snprintf.c
+/syswrap.c
diff --git a/src/interfaces/ecpg/pgtypeslib/Makefile b/src/interfaces/ecpg/pgtypeslib/Makefile
index 6c7ae63d4e2..830f47074f5 100644
--- a/src/interfaces/ecpg/pgtypeslib/Makefile
+++ b/src/interfaces/ecpg/pgtypeslib/Makefile
@@ -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 \
+	pgstrcasecmp.o syswrap.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: % : $(top_srcdir)/src/port/%
+pgstrcasecmp.c rint.c snprintf.c syswrap.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
+	rm -f $(OBJS) pgstrcasecmp.c rint.c snprintf.c syswrap.c
 
 maintainer-clean: distclean maintainer-clean-lib