diff mbox series

[net,3/4] mptcp: fix NULL pointer dereference on fastopen early fallback

Message ID 20230411-upstream-net-20230411-mptcp-fixes-v1-3-ca540f3ef986@tessares.net (mailing list archive)
State Accepted
Commit c0ff6f6da66a7791a32c0234388b1bdc00244917
Delegated to: Netdev Maintainers
Headers show
Series mptcp: more fixes for 6.3 | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net
netdev/fixes_present success Fixes tag present in non-next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 20 this patch: 20
netdev/cc_maintainers success CCed 8 of 8 maintainers
netdev/build_clang success Errors and warnings before: 18 this patch: 18
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success Fixes tag looks correct
netdev/build_allmodconfig_warn success Errors and warnings before: 20 this patch: 20
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 20 lines checked
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Matthieu Baerts April 11, 2023, 8:42 p.m. UTC 
From: Paolo Abeni <pabeni@redhat.com>

In case of early fallback to TCP, subflow_syn_recv_sock() deletes
the subflow context before returning the newly allocated sock to
the caller.

The fastopen path does not cope with the above unconditionally
dereferencing the subflow context.

Fixes: 36b122baf6a8 ("mptcp: add subflow_v(4,6)_send_synack()")
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
---
 net/mptcp/fastopen.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/net/mptcp/fastopen.c b/net/mptcp/fastopen.c
index d237d142171c..bceaab8dd8e4 100644
--- a/net/mptcp/fastopen.c
+++ b/net/mptcp/fastopen.c
@@ -9,11 +9,18 @@ 
 void mptcp_fastopen_subflow_synack_set_params(struct mptcp_subflow_context *subflow,
 					      struct request_sock *req)
 {
-	struct sock *ssk = subflow->tcp_sock;
-	struct sock *sk = subflow->conn;
+	struct sock *sk, *ssk;
 	struct sk_buff *skb;
 	struct tcp_sock *tp;
 
+	/* on early fallback the subflow context is deleted by
+	 * subflow_syn_recv_sock()
+	 */
+	if (!subflow)
+		return;
+
+	ssk = subflow->tcp_sock;
+	sk = subflow->conn;
 	tp = tcp_sk(ssk);
 
 	subflow->is_mptfo = 1;