[AX25]: UID fixes

 o Brown paperbag bug - ax25_findbyuid() was always returning a NULL pointer
   as the result.  Breaks ROSE completly and AX.25 if UID policy set to deny.

 o While the list structure of AX.25's UID to callsign mapping table was
   properly protected by a spinlock, it's elements were not refcounted
   resulting in a race between removal and usage of an element.

Signed-off-by: Ralf Baechle DL5RB <ralf@linux-mips.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 13 insertions, 7 deletions

diff --git a/net/rose/af_rose.c b/net/rose/af_rose.c
index 3fe7e562125..5480caf8ccc 100644
--- a/net/rose/af_rose.c
+++ b/net/rose/af_rose.c
@@ -626,7 +626,8 @@ static int rose_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
         struct rose_sock *rose = rose_sk(sk);
         struct sockaddr_rose *addr = (struct sockaddr_rose *)uaddr;
         struct net_device *dev;
-        ax25_address *user, *source;
+        ax25_address *source;
+        ax25_uid_assoc *user;
         int n;
 
         if (!sock_flag(sk, SOCK_ZAPPED))
@@ -651,14 +652,17 @@ static int rose_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
 
         source = &addr->srose_call;
 
-        if ((user = ax25_findbyuid(current->euid)) == NULL) {
+        user = ax25_findbyuid(current->euid);
+        if (user) {
+                rose->source_call = user->call;
+                ax25_uid_put(user);
+        } else {
                 if (ax25_uid_policy && !capable(CAP_NET_BIND_SERVICE))
                         return -EACCES;
-                user = source;
+                rose->source_call   = *source;
         }
 
         rose->source_addr   = addr->srose_addr;
-        rose->source_call   = *user;
         rose->device        = dev;
         rose->source_ndigis = addr->srose_ndigis;
 
@@ -685,8 +689,8 @@ static int rose_connect(struct socket *sock, struct sockaddr *uaddr, int addr_le
         struct rose_sock *rose = rose_sk(sk);
         struct sockaddr_rose *addr = (struct sockaddr_rose *)uaddr;
         unsigned char cause, diagnostic;
-        ax25_address *user;
         struct net_device *dev;
+        ax25_uid_assoc *user;
         int n;
 
         if (sk->sk_state == TCP_ESTABLISHED && sock->state == SS_CONNECTING) {
@@ -736,12 +740,14 @@ static int rose_connect(struct socket *sock, struct sockaddr *uaddr, int addr_le
                 if ((dev = rose_dev_first()) == NULL)
                         return -ENETUNREACH;
 
-                if ((user = ax25_findbyuid(current->euid)) == NULL)
+                user = ax25_findbyuid(current->euid);
+                if (!user)
                         return -EINVAL;
 
                 memcpy(&rose->source_addr, dev->dev_addr, ROSE_ADDR_LEN);
-                rose->source_call = *user;
+                rose->source_call = user->call;
                 rose->device      = dev;
+                ax25_uid_put(user);
 
                 rose_insert_socket(sk);         /* Finish the bind */
         }