6.1-stable review patch. If anyone has any objections, please let me know.
------------------
From: Ranganath V N vnranganath.20@gmail.com
[ Upstream commit 62b656e43eaeae445a39cd8021a4f47065af4389 ]
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 Reviewed-by: Eric Dumazet edumazet@google.com Link: https://patch.msgid.link/20251109091336.9277-2-vnranganath.20@gmail.com Acked-by: Cong Wang xiyou.wangcong@gmail.com Signed-off-by: Paolo Abeni pabeni@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- 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 79cfe51a09e74..4d75d2ae0d8ce 100644 --- a/net/sched/act_connmark.c +++ b/net/sched/act_connmark.c @@ -190,13 +190,15 @@ 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);