Tweak libpq to avoid crashing due to incorrect buffer size calculation when

we are on a 64-bit machine (ie, size_t is wider than int) and someone passes
in a query string that approaches or exceeds INT_MAX bytes.  Also, just for
paranoia's sake, guard against similar overflows in sizing the input buffer.

The backend will not in the foreseeable future be prepared to send or receive
strings exceeding 1GB, so I didn't take the more invasive step of switching
all the buffer index variables from int to size_t; though someday we might
want to do that.

I have a suspicion that this is not the only such bug in libpq, but this
fix is enough to take care of the crash reported by Francisco Reyes.

5 files changed, 25 insertions, 20 deletions

diff --git a/src/interfaces/libpq/fe-connect.c b/src/interfaces/libpq/fe-connect.c
index 55f9b2ffc7..307b8053e8 100644
--- a/src/interfaces/libpq/fe-connect.c
+++ b/src/interfaces/libpq/fe-connect.c
@@ -1581,7 +1581,8 @@ keep_going:						/* We will come back to here until there is
 					 * needed to hold the whole message; see notes in
 					 * pqParseInput3.
 					 */
-					if (pqCheckInBufferSpace(conn->inCursor + msgLength, conn))
+					if (pqCheckInBufferSpace(conn->inCursor + (size_t) msgLength,
+											 conn))
 						goto error_return;
 					/* We'll come back when there is more data */
 					return PGRES_POLLING_READING;
diff --git a/src/interfaces/libpq/fe-exec.c b/src/interfaces/libpq/fe-exec.c
index c3bc843d02..97bfcf990f 100644
--- a/src/interfaces/libpq/fe-exec.c
+++ b/src/interfaces/libpq/fe-exec.c
@@ -1685,7 +1685,8 @@ PQputCopyData(PGconn *conn, const char *buffer, int nbytes)
 		{
 			if (pqFlush(conn) < 0)
 				return -1;
-			if (pqCheckOutBufferSpace(conn->outCount + 5 + nbytes, conn))
+			if (pqCheckOutBufferSpace(conn->outCount + 5 + (size_t) nbytes,
+									  conn))
 				return pqIsnonblocking(conn) ? 0 : -1;
 		}
 		/* Send the data (too simple to delegate to fe-protocol files) */
diff --git a/src/interfaces/libpq/fe-misc.c b/src/interfaces/libpq/fe-misc.c
index 0ca46cdb11..dcb227a7ac 100644
--- a/src/interfaces/libpq/fe-misc.c
+++ b/src/interfaces/libpq/fe-misc.c
@@ -278,12 +278,12 @@ pqPutInt(int value, size_t bytes, PGconn *conn)
  * Returns 0 on success, EOF if failed to enlarge buffer
  */
 int
-pqCheckOutBufferSpace(int bytes_needed, PGconn *conn)
+pqCheckOutBufferSpace(size_t bytes_needed, PGconn *conn)
 {
 	int			newsize = conn->outBufSize;
 	char	   *newbuf;
 
-	if (bytes_needed <= newsize)
+	if (bytes_needed <= (size_t) newsize)
 		return 0;
 
 	/*
@@ -296,9 +296,9 @@ pqCheckOutBufferSpace(int bytes_needed, PGconn *conn)
 	do
 	{
 		newsize *= 2;
-	} while (bytes_needed > newsize && newsize > 0);
+	} while (newsize > 0 && bytes_needed > (size_t) newsize);
 
-	if (bytes_needed <= newsize)
+	if (newsize > 0 && bytes_needed <= (size_t) newsize)
 	{
 		newbuf = realloc(conn->outBuffer, newsize);
 		if (newbuf)
@@ -314,9 +314,9 @@ pqCheckOutBufferSpace(int bytes_needed, PGconn *conn)
 	do
 	{
 		newsize += 8192;
-	} while (bytes_needed > newsize && newsize > 0);
+	} while (newsize > 0 && bytes_needed > (size_t) newsize);
 
-	if (bytes_needed <= newsize)
+	if (newsize > 0 && bytes_needed <= (size_t) newsize)
 	{
 		newbuf = realloc(conn->outBuffer, newsize);
 		if (newbuf)
@@ -341,12 +341,12 @@ pqCheckOutBufferSpace(int bytes_needed, PGconn *conn)
  * Returns 0 on success, EOF if failed to enlarge buffer
  */
 int
-pqCheckInBufferSpace(int bytes_needed, PGconn *conn)
+pqCheckInBufferSpace(size_t bytes_needed, PGconn *conn)
 {
 	int			newsize = conn->inBufSize;
 	char	   *newbuf;
 
-	if (bytes_needed <= newsize)
+	if (bytes_needed <= (size_t) newsize)
 		return 0;
 
 	/*
@@ -359,9 +359,9 @@ pqCheckInBufferSpace(int bytes_needed, PGconn *conn)
 	do
 	{
 		newsize *= 2;
-	} while (bytes_needed > newsize && newsize > 0);
+	} while (newsize > 0 && bytes_needed > (size_t) newsize);
 
-	if (bytes_needed <= newsize)
+	if (newsize > 0 && bytes_needed <= (size_t) newsize)
 	{
 		newbuf = realloc(conn->inBuffer, newsize);
 		if (newbuf)
@@ -377,9 +377,9 @@ pqCheckInBufferSpace(int bytes_needed, PGconn *conn)
 	do
 	{
 		newsize += 8192;
-	} while (bytes_needed > newsize && newsize > 0);
+	} while (newsize > 0 && bytes_needed > (size_t) newsize);
 
-	if (bytes_needed <= newsize)
+	if (newsize > 0 && bytes_needed <= (size_t) newsize)
 	{
 		newbuf = realloc(conn->inBuffer, newsize);
 		if (newbuf)
@@ -572,7 +572,7 @@ pqReadData(PGconn *conn)
 	 */
 	if (conn->inBufSize - conn->inEnd < 8192)
 	{
-		if (pqCheckInBufferSpace(conn->inEnd + 8192, conn))
+		if (pqCheckInBufferSpace(conn->inEnd + (size_t) 8192, conn))
 		{
 			/*
 			 * We don't insist that the enlarge worked, but we need some room
diff --git a/src/interfaces/libpq/fe-protocol3.c b/src/interfaces/libpq/fe-protocol3.c
index 152f05694b..c07a827a1a 100644
--- a/src/interfaces/libpq/fe-protocol3.c
+++ b/src/interfaces/libpq/fe-protocol3.c
@@ -115,7 +115,8 @@ pqParseInput3(PGconn *conn)
 			 * recovery strategy if we are unable to make the buffer big
 			 * enough.
 			 */
-			if (pqCheckInBufferSpace(conn->inCursor + msgLength, conn))
+			if (pqCheckInBufferSpace(conn->inCursor + (size_t) msgLength,
+									 conn))
 			{
 				/*
 				 * XXX add some better recovery code... plan is to skip over
@@ -1310,7 +1311,8 @@ getCopyDataMessage(PGconn *conn)
 			 * Before returning, enlarge the input buffer if needed to hold
 			 * the whole message.  See notes in parseInput.
 			 */
-			if (pqCheckInBufferSpace(conn->inCursor + msgLength - 4, conn))
+			if (pqCheckInBufferSpace(conn->inCursor + (size_t) msgLength - 4,
+									 conn))
 			{
 				/*
 				 * XXX add some better recovery code... plan is to skip over
@@ -1745,7 +1747,8 @@ pqFunctionCall3(PGconn *conn, Oid fnid,
 			 * Before looping, enlarge the input buffer if needed to hold the
 			 * whole message.  See notes in parseInput.
 			 */
-			if (pqCheckInBufferSpace(conn->inCursor + msgLength, conn))
+			if (pqCheckInBufferSpace(conn->inCursor + (size_t) msgLength,
+									 conn))
 			{
 				/*
 				 * XXX add some better recovery code... plan is to skip over
diff --git a/src/interfaces/libpq/libpq-int.h b/src/interfaces/libpq/libpq-int.h
index 38c06d4bb7..4af13880a7 100644
--- a/src/interfaces/libpq/libpq-int.h
+++ b/src/interfaces/libpq/libpq-int.h
@@ -511,8 +511,8 @@ extern PGresult *pqFunctionCall3(PGconn *conn, Oid fnid,
   * Get, EOF merely means the buffer is exhausted, not that there is
   * necessarily any error.
   */
-extern int	pqCheckOutBufferSpace(int bytes_needed, PGconn *conn);
-extern int	pqCheckInBufferSpace(int bytes_needed, PGconn *conn);
+extern int	pqCheckOutBufferSpace(size_t bytes_needed, PGconn *conn);
+extern int	pqCheckInBufferSpace(size_t bytes_needed, PGconn *conn);
 extern int	pqGetc(char *result, PGconn *conn);
 extern int	pqPutc(char c, PGconn *conn);
 extern int	pqGets(PQExpBuffer buf, PGconn *conn);