[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, 7 insertions, 5 deletions

diff --git a/net/ax25/ax25_route.c b/net/ax25/ax25_route.c
index 44b99b1ff9f8..c288526da4ce 100644
--- a/net/ax25/ax25_route.c
+++ b/net/ax25/ax25_route.c
@@ -422,8 +422,8 @@ static inline void ax25_adjust_path(ax25_address *addr, ax25_digi *digipeat)
  */
 int ax25_rt_autobind(ax25_cb *ax25, ax25_address *addr)
 {
+        ax25_uid_assoc *user;
         ax25_route *ax25_rt;
-        ax25_address *call;
         int err;
 
         if ((ax25_rt = ax25_get_route(addr, NULL)) == NULL)
@@ -434,16 +434,18 @@ int ax25_rt_autobind(ax25_cb *ax25, ax25_address *addr)
                 goto put;
         }
 
-        if ((call = ax25_findbyuid(current->euid)) == NULL) {
+        user = ax25_findbyuid(current->euid);
+        if (user) {
+                ax25->source_addr = user->call;
+                ax25_uid_put(user);
+        } else {
                 if (ax25_uid_policy && !capable(CAP_NET_BIND_SERVICE)) {
                         err = -EPERM;
                         goto put;
                 }
-                call = (ax25_address *)ax25->ax25_dev->dev->dev_addr;
+                ax25->source_addr = *(ax25_address *)ax25->ax25_dev->dev->dev_addr;
         }
 
-        ax25->source_addr = *call;
-
         if (ax25_rt->digipeat != NULL) {
                 if ((ax25->digipeat = kmalloc(sizeof(ax25_digi), GFP_ATOMIC)) == NULL) {
                         err = -ENOMEM;