mount.nfs: Fix sockaddr pointer aliasing in stropts.c

Using a sockaddr_storage and casting a sockaddr pointer to it breaks
C's aliasing rules.

See:

  https://bugzilla.redhat.com/show_bug.cgi?id=448743

Replacing sockaddr_storage makes this code less likely to break when
optimized by gcc.  It also saves a significant amount of stack space
by replacing a 130 byte structure with a union that is less than 32
bytes.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Steve Dickson <steved@redhat.com>

diff --git a/utils/mount/stropts.c b/utils/mount/stropts.c
index 008fdbc7c9846f41100b3921ea657cad53adb3a0..c5b92fc12f4f58633d5fd17b37acf68aa23e8b4e 100644 (file)
--- a/utils/mount/stropts.c
+++ b/utils/mount/stropts.c
@@ -77,12 +77,18 @@ extern char *progname;
 extern int verbose;
 extern int sloppy;
 
+union nfs_sockaddr {
+       struct sockaddr         sa;
+       struct sockaddr_in      s4;
+       struct sockaddr_in6     s6;
+};
+
 struct nfsmount_info {
        const char              *spec,          /* server:/path */
                                *node,          /* mounted-on dir */
                                *type;          /* "nfs" or "nfs4" */
        char                    *hostname;      /* server's hostname */
-       struct sockaddr_storage address;        /* server's address */
+       union nfs_sockaddr      address;
        socklen_t               salen;          /* size of server's address */
 
        struct mount_options    *options;       /* parsed mount options */
@@ -205,9 +211,9 @@ static int nfs_append_clientaddr_option(const struct sockaddr *sap,
                                        socklen_t salen,
                                        struct mount_options *options)
 {
-       struct sockaddr_storage dummy;
-       struct sockaddr *my_addr = (struct sockaddr *)&dummy;
-       socklen_t my_len = sizeof(dummy);
+       union nfs_sockaddr address;
+       struct sockaddr *my_addr = &address.sa;
+       socklen_t my_len = sizeof(address);
 
        if (po_contains(options, "clientaddr") == PO_FOUND)
                return 1;
@@ -224,9 +230,9 @@ static int nfs_append_clientaddr_option(const struct sockaddr *sap,
  */
 static int nfs_fix_mounthost_option(struct mount_options *options)
 {
-       struct sockaddr_storage dummy;
-       struct sockaddr *sap = (struct sockaddr *)&dummy;
-       socklen_t salen = sizeof(dummy);
+       union nfs_sockaddr address;
+       struct sockaddr *sap = &address.sa;
+       socklen_t salen = sizeof(address);
        char *mounthost;
 
        mounthost = po_get(options, "mounthost");
@@ -320,7 +326,7 @@ static int nfs_set_version(struct nfsmount_info *mi)
  */
 static int nfs_validate_options(struct nfsmount_info *mi)
 {
-       struct sockaddr *sap = (struct sockaddr *)&mi->address;
+       struct sockaddr *sap = &mi->address.sa;
 
        if (!nfs_parse_devname(mi->spec, &mi->hostname, NULL))
                return 0;
@@ -453,12 +459,12 @@ static int nfs_construct_new_options(struct mount_options *options,
 static int
 nfs_rewrite_pmap_mount_options(struct mount_options *options)
 {
-       struct sockaddr_storage nfs_address;
-       struct sockaddr *nfs_saddr = (struct sockaddr *)&nfs_address;
+       union nfs_sockaddr nfs_address;
+       struct sockaddr *nfs_saddr = &nfs_address.sa;
        socklen_t nfs_salen = sizeof(nfs_address);
        struct pmap nfs_pmap;
-       struct sockaddr_storage mnt_address;
-       struct sockaddr *mnt_saddr = (struct sockaddr *)&mnt_address;
+       union nfs_sockaddr mnt_address;
+       struct sockaddr *mnt_saddr = &mnt_address.sa;
        socklen_t mnt_salen = sizeof(mnt_address);
        struct pmap mnt_pmap;
        char *option;
@@ -594,7 +600,7 @@ out_fail:
  */
 static int nfs_try_mount_v4(struct nfsmount_info *mi)
 {
-       struct sockaddr *sap = (struct sockaddr *)&mi->address;
+       struct sockaddr *sap = &mi->address.sa;
        struct mount_options *options = po_dup(mi->options);
        int result = 0;