FAILED: patch "[PATCH] mptcp: pm: kernel: correctly retransmit ADD_ADDR ID 0" failed to apply to 6.12-stable tree

PATCH New [email protected] 2 participants 2 messages May 12 – May 18

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[email protected]

author maintainer

2026-05-12 14:20 UTC #0 lore raw

The patch below does not apply to the 6.12-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.12.y
git checkout FETCH_HEAD
git cherry-pick -x b12014d2d36eaed4e4bec5f1ac7e91110eeb100d
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026051243-corncob-shrubbery-862b@gregkh' --subject-prefix 'PATCH 6.12.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From b12014d2d36eaed4e4bec5f1ac7e91110eeb100d Mon Sep 17 00:00:00 2001
From: "Matthieu Baerts (NGI0)" <[email protected]>
Date: Tue, 5 May 2026 17:00:49 +0200
Subject: [PATCH] mptcp: pm: kernel: correctly retransmit ADD_ADDR ID 0

When adding the ADD_ADDR to the list, the address including the IP, port and ID are copied. On the other hand, when the endpoint corresponds to the one from the initial subflow, the ID is set to 0, as specified by the MPTCP protocol.

The issue is that the ID was reset after having copied the ID in the ADD_ADDR entry. So the retransmission was done, but using a different ID than the initial one.

Fixes 8b8ed1b429f8 ("mptcp: pm: reuse ID 0 after delete and re-add")

Cc [email protected]

Reviewed-by Mat Martineau <[email protected]>

Signed-off-by Matthieu Baerts (NGI0) <[email protected]>

Link https://patch.msgid.link/[email protected] open here

Signed-off-by Jakub Kicinski <[email protected]>

net/mptcp/pm_kernel.c +8 -5

index c9f1e5af3cd3..fc818b63752e 100644
@@ -347,6 +347,8 @@ static void mptcp_pm_create_subflow_or_signal_addr(struct mptcp_sock *msk)
 
 	/* check first for announce */
 	if (msk->pm.add_addr_signaled < endp_signal_max) {
+		u8 endp_id;
+
 		/* due to racing events on both ends we can reach here while
 		 * previous add address is still running: if we invoke now
 		 * mptcp_pm_announce_addr(), that will fail and the

@@ -360,19 +362,20 @@ static void mptcp_pm_create_subflow_or_signal_addr(struct mptcp_sock *msk)
 		if (!select_signal_address(pernet, msk, &local))
 			goto subflow;
 
+		/* Special case for ID0: set the correct ID */
+		endp_id = local.addr.id;
+		if (endp_id == msk->mpc_endpoint_id)
+			local.addr.id = 0;
+
 		/* If the alloc fails, we are on memory pressure, not worth
 		 * continuing, and trying to create subflows.
 		 */
 		if (!mptcp_pm_alloc_anno_list(msk, &local.addr))
 			return;
 
-		__clear_bit(local.addr.id, msk->pm.id_avail_bitmap);
+		__clear_bit(endp_id, msk->pm.id_avail_bitmap);
 		msk->pm.add_addr_signaled++;
 
-		/* Special case for ID0: set the correct ID */
-		if (local.addr.id == msk->mpc_endpoint_id)
-			local.addr.id = 0;
-
 		mptcp_pm_announce_addr(msk, &local.addr, false);
 		mptcp_pm_addr_send_ack(msk);

Sasha Levin

maintainer

2026-05-18 13:05 UTC #1 lore raw

PATCH 1/1 mptcp: pm: kernel: correctly retransmit ADD_ADDR ID 0

From: "Matthieu Baerts (NGI0)" <[email protected]>

[ Upstream commit b12014d2d36eaed4e4bec5f1ac7e91110eeb100d ]

The issue is that the ID was reset after having copied the ID in the ADD_ADDR entry. So the retransmission was done, but using a different ID than the initial one.

Fixes 8b8ed1b429f8 ("mptcp: pm: reuse ID 0 after delete and re-add")

Cc [email protected]

Reviewed-by Mat Martineau <[email protected]>

Signed-off-by Matthieu Baerts (NGI0) <[email protected]>

Link https://patch.msgid.link/[email protected] open here

Signed-off-by Jakub Kicinski <[email protected]>

[ applied to net/mptcp/pm_netlink.c instead of upstream's pm_kernel.c ]

Signed-off-by Sasha Levin <[email protected]>

---
 net/mptcp/pm_netlink.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

net/mptcp/pm_netlink.c +8 -5

index 3ac09bfe6e4b2..e414e3b7773bd 100644
@@ -590,6 +590,8 @@ static void mptcp_pm_create_subflow_or_signal_addr(struct mptcp_sock *msk)
 
 	/* check first for announce */
 	if (msk->pm.add_addr_signaled < add_addr_signal_max) {
+		u8 endp_id;
+
 		/* due to racing events on both ends we can reach here while
 		 * previous add address is still running: if we invoke now
 		 * mptcp_pm_announce_addr(), that will fail and the

@@ -603,19 +605,20 @@ static void mptcp_pm_create_subflow_or_signal_addr(struct mptcp_sock *msk)
 		if (!select_signal_address(pernet, msk, &local))
 			goto subflow;
 
+		/* Special case for ID0: set the correct ID */
+		endp_id = local.addr.id;
+		if (endp_id == msk->mpc_endpoint_id)
+			local.addr.id = 0;
+
 		/* If the alloc fails, we are on memory pressure, not worth
 		 * continuing, and trying to create subflows.
 		 */
 		if (!mptcp_pm_alloc_anno_list(msk, &local.addr))
 			return;
 
-		__clear_bit(local.addr.id, msk->pm.id_avail_bitmap);
+		__clear_bit(endp_id, msk->pm.id_avail_bitmap);
 		msk->pm.add_addr_signaled++;
 
-		/* Special case for ID0: set the correct ID */
-		if (local.addr.id == msk->mpc_endpoint_id)
-			local.addr.id = 0;
-
 		mptcp_pm_announce_addr(msk, &local.addr, false);
 		mptcp_pm_nl_addr_send_ack(msk);

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