diff mbox series

[net-next,5/9] mptcp: hold mptcp socket before calling tcp_done

Message ID 20201210222506.222251-6-mathew.j.martineau@linux.intel.com (mailing list archive)
State Accepted
Commit ab82e996a1fa1b9ae514fa357d9ce8df62321157
Delegated to: Netdev Maintainers
Headers show
Series mptcp: Another set of miscellaneous MPTCP fixes | expand

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Context Check Description
netdev/cover_letter success Link
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netdev/patch_count success Link
netdev/tree_selection success Clearly marked for net-next
netdev/subject_prefix success Link
netdev/source_inline success Was 0 now: 0
netdev/verify_signedoff success Link
netdev/module_param success Was 0 now: 0
netdev/build_32bit success Errors and warnings before: 1 this patch: 1
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/verify_fixes success Link
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 18 lines checked
netdev/build_allmodconfig_warn success Errors and warnings before: 1 this patch: 1
netdev/header_inline success Link
netdev/stable success Stable not CCed

Commit Message

Mat Martineau Dec. 10, 2020, 10:25 p.m. UTC 
From: Florian Westphal <fw@strlen.de>

When processing options from tcp reset path its possible that
tcp_done(ssk) drops the last reference on the mptcp socket which
results in use-after-free.

Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
---
 net/mptcp/subflow.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index bf808f1fabe5..73e66a406d99 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -313,12 +313,17 @@  void mptcp_subflow_reset(struct sock *ssk)
 	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
 	struct sock *sk = subflow->conn;
 
+	/* must hold: tcp_done() could drop last reference on parent */
+	sock_hold(sk);
+
 	tcp_set_state(ssk, TCP_CLOSE);
 	tcp_send_active_reset(ssk, GFP_ATOMIC);
 	tcp_done(ssk);
 	if (!test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &mptcp_sk(sk)->flags) &&
 	    schedule_work(&mptcp_sk(sk)->work))
-		sock_hold(sk);
+		return; /* worker will put sk for us */
+
+	sock_put(sk);
 }
 
 static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)