[PATCH xserver 1/2] os: Move OsCommPtr dereference after ignoreCount check

[Chris Wilson]

Make AttendClient safe to call along the client teardown path (i.e.
after CloseDownConnection which is called before the Client's resources
are freed) by checking the ClientPtr before the OsCommPtr.

References: https://bugs.freedesktop.org/show_bug.cgi?id=94074
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Adam Jackson <ajax at nwnk.net>
---
 os/connection.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/os/connection.c b/os/connection.c
index 4c1ba4b..be3e4d1 100644
--- a/os/connection.c
+++ b/os/connection.c
@@ -1254,12 +1254,13 @@ void
 IgnoreClient(ClientPtr client)
 {
     OsCommPtr oc = (OsCommPtr) client->osPrivate;
-    int connection = oc->fd;
+    int connection;
 
     client->ignoreCount++;
     if (client->ignoreCount > 1)
         return;
 
+    connection = oc->fd;
     isItTimeToYield = TRUE;
     if (!GrabInProgress || FD_ISSET(connection, &AllClients)) {
         if (FD_ISSET(connection, &ClientsWithInput))
@@ -1291,12 +1292,13 @@ void
 AttendClient(ClientPtr client)
 {
     OsCommPtr oc = (OsCommPtr) client->osPrivate;
-    int connection = oc->fd;
+    int connection;
 
     client->ignoreCount--;
     if (client->ignoreCount)
         return;
 
+    connection = oc->fd;
     if (!GrabInProgress || GrabInProgress == client->index ||
         FD_ISSET(connection, &GrabImperviousClients)) {
         FD_SET(connection, &AllClients);
-- 
2.7.0