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mptcp: pm: Defer freeing of MPTCP userspace path manager entries

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When path manager entries are deleted from the local address list, they
are first unlinked from the address list using list_del_rcu(). The
entries must not be freed until after the RCU grace period, but the
existing code immediately frees the entry.

Use kfree_rcu_mightsleep() and adjust sk_omem_alloc in open code instead
of using the sock_kfree_s() helper. This code path is only called in a
netlink handler, so the "might sleep" function is preferable to adding
a rarely-used rcu_head member to struct mptcp_pm_addr_entry.

Fixes: 88d0973163 ("mptcp: drop free_list for deleting entries")
Cc: stable@vger.kernel.org
Signed-off-by: Mat Martineau <martineau@kernel.org>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20250421-net-mptcp-pm-defer-freeing-v1-1-e731dc6e86b9@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Mat Martineau 2025-04-21 19:07:13 +02:00 committed by Jakub Kicinski
parent 491ef1117c
commit 13b4ece33c
1 changed files with 5 additions and 1 deletions
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6
net/mptcp/pm_userspace.c
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@ -337,7 +337,11 @@ int mptcp_pm_nl_remove_doit(struct sk_buff *skb, struct genl_info *info)
release_sock(sk);
sock_kfree_s(sk, match, sizeof(*match));
kfree_rcu_mightsleep(match);
/* Adjust sk_omem_alloc like sock_kfree_s() does, to match
* with allocation of this memory by sock_kmemdup()
*/
atomic_sub(sizeof(*match), &sk->sk_omem_alloc);
err = 0;
out: