mptcp: fix KMSAN: uninit-value in mptcp_established_options

matttbe · intel-lab-lkp · commit d0344112f822 · 2026-05-12T21:09:36.000+08:00
Just to let syzbot testing it. See Paolo's suggestion from [1]. Link: https://lore.kernel.org/6d342ef2-d480-4be6-afad-a3841cf205a8@redhat.com [1] Fixes: cfcceb7 ("tcp: shrink per-packet memset in __tcp_transmit_skb()") Reported-by: syzbot+ff020673c5e3d94d9478@syzkaller.appspotmail.com Closes: https://lore.kernel.org/69f44505.050a0220.3cbe47.0008.GAE@google.com Suggested-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
diff --git a/net/mptcp/options.c b/net/mptcp/options.c
@@ -583,6 +583,8 @@ static bool mptcp_established_options_dss(struct sock *sk, struct sk_buff *skb,
 				map_size += TCPOLEN_MPTCP_DSS_CHECKSUM;
 
 			opts->ext_copy = *mpext;
+		} else {
+			opts->ext_copy.use_map = 0;
 		}
 
 		dss_size = map_size;

Original file line number	Diff line number	Diff line change
`@@ -583,6 +583,8 @@ static bool mptcp_established_options_dss(struct sock sk, struct sk_buff skb,`
`583`	`583`	`map_size += TCPOLEN_MPTCP_DSS_CHECKSUM;`
`584`	`584`
`585`	`585`	`opts->ext_copy = *mpext;`
	`586`	`+ } else {`
	`587`	`+ opts->ext_copy.use_map = 0;`
`586`	`588`	`}`
`587`	`589`
`588`	`590`	`dss_size = map_size;`