5.4-stable review patch. If anyone has any objections, please let me know.
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From: Ranganath V N vnranganath.20@gmail.com
[ Upstream commit ce50039be49eea9b4cd8873ca6eccded1b4a130a ]
Fix a KMSAN kernel-infoleak detected by the syzbot .
[net?] KMSAN: kernel-infoleak in __skb_datagram_iter
In tcf_ife_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.
This change silences the KMSAN report and prevents potential information leaks from the kernel memory.
This fix has been tested and validated by syzbot. This patch closes the bug reported at the following syzkaller link and ensures no infoleak.
Reported-by: syzbot+0c85cae3350b7d486aee@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=0c85cae3350b7d486aee Tested-by: syzbot+0c85cae3350b7d486aee@syzkaller.appspotmail.com Fixes: ef6980b6becb ("introduce IFE action") Signed-off-by: Ranganath V N vnranganath.20@gmail.com Reviewed-by: Eric Dumazet edumazet@google.com Link: https://patch.msgid.link/20251109091336.9277-3-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_ife.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/net/sched/act_ife.c b/net/sched/act_ife.c index 488d10476e850..8f82842ad8cb5 100644 --- a/net/sched/act_ife.c +++ b/net/sched/act_ife.c @@ -642,13 +642,15 @@ static int tcf_ife_dump(struct sk_buff *skb, struct tc_action *a, int bind, unsigned char *b = skb_tail_pointer(skb); struct tcf_ife_info *ife = to_ife(a); struct tcf_ife_params *p; - struct tc_ife opt = { - .index = ife->tcf_index, - .refcnt = refcount_read(&ife->tcf_refcnt) - ref, - .bindcnt = atomic_read(&ife->tcf_bindcnt) - bind, - }; + struct tc_ife opt; struct tcf_t t;
+ memset(&opt, 0, sizeof(opt)); + + opt.index = ife->tcf_index, + opt.refcnt = refcount_read(&ife->tcf_refcnt) - ref, + opt.bindcnt = atomic_read(&ife->tcf_bindcnt) - bind, + spin_lock_bh(&ife->tcf_lock); opt.action = ife->tcf_action; p = rcu_dereference_protected(ife->params,