[X2Go-Commits] [nx-libs] 07/30: ProcGetPointerMapping uses rep.nElts before it is initialized

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Tue Jul 3 22:23:58 CEST 2018

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x2go pushed a commit to branch 3.6.x
in repository nx-libs.

commit 389e3a4459e3b61eea3a21aba560122dbca264e6
Author: Ulrich Sibiller <uli42 at gmx.de>
Date:   Thu Jun 21 22:08:08 2018 +0200

    ProcGetPointerMapping uses rep.nElts before it is initialized
    Backport of this xorg upstream commit (with omitting the mentioned
      commit 34cf559bcf99dad550527b5ff53f247f0e8e73ee
      Author: Keith Packard <keithp at keithp.com>
      Date:   Tue Jul 10 15:58:48 2012 -0700
        ProcGetPointerMapping uses rep.nElts before it is initialized
                commit d792ac125a0462a04a930af543cbc732f8cdab7d
                Author: Alan Coopersmith <alan.coopersmith at oracle.com>
                Date:   Mon Jul 9 19:12:43 2012 -0700
                    Use C99 designated initializers in dix Replies
        the initializer for the .length element of the xGetPointerMappingReply
        structure uses the value of rep.nElts, but that won't be set until
        after this initializer runs, so we get garbage in the length element
        and clients using it will generally wedge.
        Easy to verify:
                $ xmodmap -pp
        Fixed by creating a local nElts variable and using that.
        Signed-off-by: Keith Packard <keithp at keithp.com>
        Reviewed-by: Alan Coopersmith <alan.coopersmith at oracle.com>
    Backported-to-NX-by: Ulrich Sibiller <uli42 at gmx.de>
 nx-X11/programs/Xserver/dix/devices.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/nx-X11/programs/Xserver/dix/devices.c b/nx-X11/programs/Xserver/dix/devices.c
index d31ff82..51cf3fe 100644
--- a/nx-X11/programs/Xserver/dix/devices.c
+++ b/nx-X11/programs/Xserver/dix/devices.c
@@ -1156,17 +1156,20 @@ ProcGetKeyboardMapping(ClientPtr client)
 ProcGetPointerMapping(ClientPtr client)
+    int nElts;
     xGetPointerMappingReply rep = {0};
     ButtonClassPtr butc = inputInfo.pointer->button;
+    nElts = (butc) ? butc->numButtons : 0;
     rep.type = X_Reply;
+    rep.nElts = nElts;
     rep.sequenceNumber = client->sequence;
-    rep.nElts = butc->numButtons;
-    rep.length = ((unsigned)rep.nElts + (4-1))/4;
+    rep.length = ((unsigned)nElts + (4-1))/4;
     WriteReplyToClient(client, sizeof(xGetPointerMappingReply), &rep);
-    WriteToClient(client, (int)rep.nElts, &butc->map[1]);
+    if (butc)
+        WriteToClient(client, nElts, &butc->map[1]);
     return Success;

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