Fix unportable disregard of alignment requirements in RADIUS code.

The compiler is entitled to store a char[] local variable with no
particular alignment requirement.  Our RADIUS code cavalierly took such
a local variable and cast its address to a struct type that does have
alignment requirements.  On an alignment-picky machine this would lead
to bus errors.  To fix, declare the local variable honestly, and then
cast its address to char * for use in the I/O calls.

Given the lack of field complaints, there must be very few if any
people affected; but nonetheless this is a clear portability issue,
so back-patch to all supported branches.

Noted while looking at a Coverity complaint in the same code.

diff --git a/src/backend/libpq/auth.c b/src/backend/libpq/auth.c
index 127c6cf45e9f7729d070b3200913d2bb26ea304f..f585ae0aed991cfbc9e86b98134339317b40b9cf 100644 (file)
--- a/src/backend/libpq/auth.c
+++ b/src/backend/libpq/auth.c
@@ -2355,14 +2355,16 @@ CheckCertAuth(Port *port)
  */
 
 /*
- * RADIUS authentication is described in RFC2865 (and several
- * others).
+ * RADIUS authentication is described in RFC2865 (and several others).
  */
 
 #define RADIUS_VECTOR_LENGTH 16
 #define RADIUS_HEADER_LENGTH 20
 #define RADIUS_MAX_PASSWORD_LENGTH 128
 
+/* Maximum size of a RADIUS packet we will create or accept */
+#define RADIUS_BUFFER_SIZE 1024
+
 typedef struct
 {
        uint8           attribute;
@@ -2376,6 +2378,8 @@ typedef struct
        uint8           id;
        uint16          length;
        uint8           vector[RADIUS_VECTOR_LENGTH];
+       /* this is a bit longer than strictly necessary: */
+       char            pad[RADIUS_BUFFER_SIZE - RADIUS_VECTOR_LENGTH];
 } radius_packet;
 
 /* RADIUS packet types */
@@ -2392,9 +2396,6 @@ typedef struct
 /* RADIUS service types */
 #define RADIUS_AUTHENTICATE_ONLY       8
 
-/* Maximum size of a RADIUS packet we will create or accept */
-#define RADIUS_BUFFER_SIZE 1024
-
 /* Seconds to wait - XXX: should be in a config variable! */
 #define RADIUS_TIMEOUT 3
 
@@ -2429,10 +2430,12 @@ CheckRADIUSAuth(Port *port)
 {
        char       *passwd;
        char       *identifier = "postgresql";
-       char            radius_buffer[RADIUS_BUFFER_SIZE];
-       char            receive_buffer[RADIUS_BUFFER_SIZE];
-       radius_packet *packet = (radius_packet *) radius_buffer;
-       radius_packet *receivepacket = (radius_packet *) receive_buffer;
+       radius_packet radius_send_pack;
+       radius_packet radius_recv_pack;
+       radius_packet *packet = &radius_send_pack;
+       radius_packet *receivepacket = &radius_recv_pack;
+       char       *radius_buffer = (char *) &radius_send_pack;
+       char       *receive_buffer = (char *) &radius_recv_pack;
        int32           service = htonl(RADIUS_AUTHENTICATE_ONLY);
        uint8      *cryptvector;
        int                     encryptedpasswordlen;