From 04f217aca4d803fe72c2c54fe460d68f5233ce52 Mon Sep 17 00:00:00 2001 From: Stephen Hemminger Date: Thu, 7 Feb 2008 18:13:00 -0800 Subject: [PATCH] [TC]: oops in em_meta 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 Signed-off-by: David S. Miller --- net/sched/em_meta.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/net/sched/em_meta.c b/net/sched/em_meta.c index 2a7e648fbcf..d417ec8e3ca 100644 --- a/net/sched/em_meta.c +++ b/net/sched/em_meta.c @@ -735,11 +735,13 @@ 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); -- 2.41.1