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Message-ID: <20240904174537.317976-2-matttbe@kernel.org>
Date: Wed, 4 Sep 2024 19:45:38 +0200
From: "Matthieu Baerts (NGI0)" <matttbe@...nel.org>
To: syzbot+f3a31fb909db9b2a5c4d@...kaller.appspotmail.com
Cc: linux-kernel@...r.kernel.org,
"Matthieu Baerts (NGI0)" <matttbe@...nel.org>
Subject: [PATCH net v2] mptcp: pm: Fix uaf in __timer_delete_sync
#syz test
v2: include Edward's patch, easier to test with syzbot.
Fixes: 00cfd77b9063 ("mptcp: retransmit ADD_ADDR when timeout")
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@...nel.org>
---
net/mptcp/pm_netlink.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)
diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
index f891bc714668..3a5839ba92f1 100644
--- a/net/mptcp/pm_netlink.c
+++ b/net/mptcp/pm_netlink.c
@@ -332,17 +332,21 @@ struct mptcp_pm_add_entry *
mptcp_pm_del_add_timer(struct mptcp_sock *msk,
const struct mptcp_addr_info *addr, bool check_id)
{
- struct mptcp_pm_add_entry *entry;
struct sock *sk = (struct sock *)msk;
+ struct timer_list *add_timer = NULL;
+ struct mptcp_pm_add_entry *entry;
spin_lock_bh(&msk->pm.lock);
entry = mptcp_lookup_anno_list_by_saddr(msk, addr);
- if (entry && (!check_id || entry->addr.id == addr->id))
+ if (entry && (!check_id || entry->addr.id == addr->id)) {
entry->retrans_times = ADD_ADDR_RETRANS_MAX;
+ add_timer = &entry->add_timer;
+ }
spin_unlock_bh(&msk->pm.lock);
- if (entry && (!check_id || entry->addr.id == addr->id))
- sk_stop_timer_sync(sk, &entry->add_timer);
+ /* no lock, because sk_stop_timer_sync() is calling del_timer_sync() */
+ if (add_timer)
+ sk_stop_timer_sync(sk, add_timer);
return entry;
}
@@ -1462,8 +1466,10 @@ static bool remove_anno_list_by_saddr(struct mptcp_sock *msk,
entry = mptcp_pm_del_add_timer(msk, addr, false);
if (entry) {
+ spin_lock_bh(&msk->pm.lock);
list_del(&entry->list);
kfree(entry);
+ spin_unlock_bh(&msk->pm.lock);
return true;
}
--
2.45.2
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