In tcf_connmark_dump(), the variable 'opt' was partially initialized using a
designatied initializer. While the padding bytes are reamined
uninitialized. nla_put() copies the entire structure into a
netlink message, these uninitialized bytes leaked to userspace.
Initialize the structure with memset before assigning its fields
to ensure all members and padding are cleared prior to beign copied.
Reported-by: syzbot+0c85cae3350b7d486aee@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=0c85cae3350b7d486aee
Tested-by: syzbot+0c85cae3350b7d486aee@syzkaller.appspotmail.com
Fixes: 22a5dc0e5e3e ("net: sched: Introduce connmark action")
Signed-off-by: Ranganath V N <vnranganath.20@gmail.com>
---
net/sched/act_connmark.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/net/sched/act_connmark.c b/net/sched/act_connmark.c
index 3e89927d7116..26ba8c2d20ab 100644
--- a/net/sched/act_connmark.c
+++ b/net/sched/act_connmark.c
@@ -195,13 +195,15 @@ static inline int tcf_connmark_dump(struct sk_buff *skb, struct tc_action *a,
const struct tcf_connmark_info *ci = to_connmark(a);
unsigned char *b = skb_tail_pointer(skb);
const struct tcf_connmark_parms *parms;
- struct tc_connmark opt = {
- .index = ci->tcf_index,
- .refcnt = refcount_read(&ci->tcf_refcnt) - ref,
- .bindcnt = atomic_read(&ci->tcf_bindcnt) - bind,
- };
+ struct tc_connmark opt;
struct tcf_t t;
+ memset(&opt, 0, sizeof(opt));
+
+ opt.index = ci->tcf_index;
+ opt.refcnt = refcount_read(&ci->tcf_refcnt) - ref;
+ opt.bindcnt = atomic_read(&ci->tcf_bindcnt) - bind;
+
rcu_read_lock();
parms = rcu_dereference(ci->parms);
--
2.43.0