commit 79a25f70244c66402c99d9b32d19204dfded85d0
Author: Stephen Hemminger <[EMAIL PROTECTED]>
Date:   Fri Feb 15 01:37:49 2008 -0800

    TC: oops in em_meta
    
    Upstream commit: 04f217aca4d803fe72c2c54fe460d68f5233ce52
    
    If userspace passes a unknown match index into em_meta, then
    em_meta_change will return an error and the data for the match will
    not be set. This then causes an null pointer dereference when the
    cleanup is done in the error path via tcf_em_tree_destroy. Since the
    tree structure comes kzalloc, it is initialized to NULL.
    
    Discovered when testing a new version of tc command against an
    accidental older kernel.
    
    Signed-off-by: Stephen Hemminger <[EMAIL PROTECTED]>
    Signed-off-by: David S. Miller <[EMAIL PROTECTED]>
    Signed-off-by: Greg Kroah-Hartman <[EMAIL PROTECTED]>

diff --git a/net/sched/em_meta.c b/net/sched/em_meta.c
index ceda889..4d5ce77 100644
--- a/net/sched/em_meta.c
+++ b/net/sched/em_meta.c
@@ -719,11 +719,13 @@ static int em_meta_match(struct sk_buff *skb, struct 
tcf_ematch *m,
 
 static inline void meta_delete(struct meta_match *meta)
 {
-       struct meta_type_ops *ops = meta_type_ops(&meta->lvalue);
+       if (meta) {
+               struct meta_type_ops *ops = meta_type_ops(&meta->lvalue);
 
-       if (ops && ops->destroy) {
-               ops->destroy(&meta->lvalue);
-               ops->destroy(&meta->rvalue);
+               if (ops && ops->destroy) {
+                       ops->destroy(&meta->lvalue);
+                       ops->destroy(&meta->rvalue);
+               }
        }
 
        kfree(meta);
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