FAILED: patch "[PATCH] netfilter: nf_conntrack: defer invalid log until after unlock" failed to apply to 6.1-stable tree

PATCH New [email protected] 2 participants 3 messages Aug 17 – Aug 20

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2026-08-17 12:44 UTC #0 lore raw

The patch below does not apply to the 6.1-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-6.1.y
git checkout FETCH_HEAD
git cherry-pick -x 2d19b95c9723001f214f7a47d67b09f46238f200
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026081731-reflux-overcrowd-ff11@gregkh' --subject-prefix 'PATCH 6.1.y' 'HEAD^..'

Possible dependencies:

thanks,

greg k-h

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

From 2d19b95c9723001f214f7a47d67b09f46238f200 Mon Sep 17 00:00:00 2001
From: Zihan Xi <[email protected]>
Date: Sat, 1 Aug 2026 14:27:17 +0000
Subject: [PATCH] netfilter: nf_conntrack: defer invalid log until after unlock

TCP and SCTP conntrack paths can emit invalid-packet logs while ct->lock is still held.

When invalid logging is routed to nfnetlink_log and conntrack export is enabled, the log path can re-enter conntrack netlink glue and dump the same conntrack again. Protocol attribute dumping may take ct->lock, so logging while holding that lock can deadlock.

Defer the TCP invalid logs by storing only the minimal log context while ct->lock is held and emitting the log after unlocking. Also make the TCP timeout-lowering invalid path return whether a log is needed, then emit that log after unlocking.

Do the same for the SCTP invalid state-transition log that can be reached while ct->lock is held.

Add a lockdep assertion to nf_ct_l4proto_log_invalid() so future callers that log invalid conntracks while holding ct->lock are caught outside TCP and SCTP as well.

Fixes 628d694344a0 ("netfilter: conntrack: reduce timeout when receiving out-of-window fin or rst")

Fixes d9a6f0d0df18 ("netfilter: conntrack: prepare tcp_in_window for ternary return value")

Fixes f71cb8f45d09 ("netfilter: conntrack: sctp: use nf log infrastructure for invalid packets")

Cc [email protected]

Reported-by Vega <[email protected]>

Assisted-by Codex:gpt-5.4

Signed-off-by Zihan Xi <[email protected]>

Reviewed-by Florian Westphal <[email protected]>

Signed-off-by Pablo Neira Ayuso <[email protected]>

net/netfilter/nf_conntrack_proto.c +6 -0

index ad96896516b6..7a40e4e0e33e 100644
@@ -79,6 +79,12 @@ void nf_ct_l4proto_log_invalid(const struct sk_buff *skb,
 	struct net *net;
 	va_list args;
 
+	/* nfnetlink_log may re-enter conntrack attribute dumping and try to
+	 * take ct->lock again via helpers such as tcp_to_nlattr(), so invalid
+	 * conntrack logs must only be emitted after dropping ct->lock.
+	 */
+	lockdep_assert_not_held(&ct->lock);
+
 	net = nf_ct_net(ct);
 	if (likely(net->ct.sysctl_log_invalid == 0))
 		return;

net/netfilter/nf_conntrack_proto_sctp.c +8 -4

index 7e10fa65cbdd..71cc920f6856 100644
@@ -336,10 +336,12 @@ int nf_conntrack_sctp_packet(struct nf_conn *ct,
 	struct sctphdr _sctph;
 	const struct sctp_chunkhdr *sch;
 	struct sctp_chunkhdr _sch;
+	bool log_invalid = false;
 	u_int32_t offset, count;
 	unsigned int *timeouts;
 	unsigned long map[256 / sizeof(unsigned long)] = { 0 };
 	bool ignore = false;
+	u8 invalid_type = 0;
 
 	if (sctp_error(skb, dataoff, state))
 		return -NF_ACCEPT;

@@ -451,10 +453,8 @@ int nf_conntrack_sctp_packet(struct nf_conn *ct,
 
 		/* Invalid */
 		if (new_state == SCTP_CONNTRACK_MAX) {
-			nf_ct_l4proto_log_invalid(skb, ct, state,
-						  "Invalid, old_state %d, dir %d, type %d",
-						  old_state, dir, sch->type);
-
+			log_invalid = true;
+			invalid_type = sch->type;
 			goto out_unlock;
 		}

@@ -529,6 +529,10 @@ int nf_conntrack_sctp_packet(struct nf_conn *ct,
 
 out_unlock:
 	spin_unlock_bh(&ct->lock);
+	if (log_invalid)
+		nf_ct_l4proto_log_invalid(skb, ct, state,
+					  "Invalid, old_state %d, dir %d, type %d",
+					  old_state, dir, invalid_type);
 out:
 	return -NF_ACCEPT;
 }

net/netfilter/nf_conntrack_proto_tcp.c +88 ~~-44~~

225 lines not on this page · raw message

Sasha Levin

maintainer

2026-08-20 04:22 UTC #1 lore raw

PATCH 1/2 netfilter: conntrack: sctp: use nf log infrastructure for invalid packets

From: Florian Westphal <[email protected]>

[ Upstream commit f71cb8f45d092a1805e9ad474b6c6a17219cede5 ]

The conntrack logging facilities include useful info such as in/out interface names and packet headers.

Use those in more places instead of pr_debug calls. Furthermore, several pr_debug calls can be removed, they are useless on production machines due to the sheer volume of log messages.

Signed-off-by Florian Westphal <[email protected]>

Stable-dep-of: 2d19b95c9723 ("netfilter: nf_conntrack: defer invalid log until after unlock")

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

---
 net/netfilter/nf_conntrack_proto_sctp.c | 44 +++++++++----------------
 1 file changed, 15 insertions(+), 29 deletions(-)

net/netfilter/nf_conntrack_proto_sctp.c +15 ~~-29~~

index ae89f3c590e8b..db5c32ca996bd 100644
@@ -152,7 +152,8 @@ for ((offset) = (dataoff) + sizeof(struct sctphdr), (count) = 0;	\
 static int do_basic_checks(struct nf_conn *ct,
 			   const struct sk_buff *skb,
 			   unsigned int dataoff,
-			   unsigned long *map)
+			   unsigned long *map,
+			   const struct nf_hook_state *state)
 {
 	u_int32_t offset, count;
 	struct sctp_chunkhdr _sch, *sch;

@@ -161,8 +162,6 @@ static int do_basic_checks(struct nf_conn *ct,
 	flag = 0;
 
 	for_each_sctp_chunk (skb, sch, _sch, offset, dataoff, count) {
-		pr_debug("Chunk Num: %d  Type: %d\n", count, sch->type);
-
 		if (sch->type == SCTP_CID_INIT ||
 		    sch->type == SCTP_CID_INIT_ACK ||
 		    sch->type == SCTP_CID_SHUTDOWN_COMPLETE)

@@ -177,7 +176,9 @@ static int do_basic_checks(struct nf_conn *ct,
 		      sch->type == SCTP_CID_COOKIE_ECHO ||
 		      flag) &&
 		     count != 0) || !sch->length) {
-			pr_debug("Basic checks failed\n");
+			nf_ct_l4proto_log_invalid(skb, ct, state,
+						  "%s failed. chunk num %d, type %d, len %d flag %d\n",
+						  __func__, count, sch->type, sch->length, flag);
 			return 1;
 		}

@@ -185,7 +186,6 @@ static int do_basic_checks(struct nf_conn *ct,
 			set_bit(sch->type, map);
 	}
 
-	pr_debug("Basic checks passed\n");
 	return count == 0;
 }

@@ -195,64 +195,47 @@ static int sctp_new_state(enum ip_conntrack_dir dir,
 {
 	int i;
 
-	pr_debug("Chunk type: %d\n", chunk_type);
-
 	switch (chunk_type) {
 	case SCTP_CID_INIT:
-		pr_debug("SCTP_CID_INIT\n");
 		i = 0;
 		break;
 	case SCTP_CID_INIT_ACK:
-		pr_debug("SCTP_CID_INIT_ACK\n");
 		i = 1;
 		break;
 	case SCTP_CID_ABORT:
-		pr_debug("SCTP_CID_ABORT\n");
 		i = 2;
 		break;
 	case SCTP_CID_SHUTDOWN:
-		pr_debug("SCTP_CID_SHUTDOWN\n");
 		i = 3;
 		break;
 	case SCTP_CID_SHUTDOWN_ACK:
-		pr_debug("SCTP_CID_SHUTDOWN_ACK\n");
 		i = 4;
 		break;
 	case SCTP_CID_ERROR:
-		pr_debug("SCTP_CID_ERROR\n");
 		i = 5;
 		break;
 	case SCTP_CID_COOKIE_ECHO:
-		pr_debug("SCTP_CID_COOKIE_ECHO\n");
 		i = 6;
 		break;
 	case SCTP_CID_COOKIE_ACK:
-		pr_debug("SCTP_CID_COOKIE_ACK\n");
 		i = 7;
 		break;
 	case SCTP_CID_SHUTDOWN_COMPLETE:
-		pr_debug("SCTP_CID_SHUTDOWN_COMPLETE\n");
 		i = 8;
 		break;
 	case SCTP_CID_HEARTBEAT:
-		pr_debug("SCTP_CID_HEARTBEAT");
 		i = 9;
 		break;
 	case SCTP_CID_HEARTBEAT_ACK:
-		pr_debug("SCTP_CID_HEARTBEAT_ACK");
 		i = 10;
 		break;
 	default:
 		/* Other chunks like DATA or SACK do not change the state */
-		pr_debug("Unknown chunk type, Will stay in %s\n",
-			 sctp_conntrack_names[cur_state]);
+		pr_debug("Unknown chunk type %d, Will stay in %s\n",
+			 chunk_type, sctp_conntrack_names[cur_state]);
 		return cur_state;
 	}
 
-	pr_debug("dir: %d   cur_state: %s  chunk_type: %d  new_state: %s\n",
-		 dir, sctp_conntrack_names[cur_state], chunk_type,
-		 sctp_conntrack_names[sctp_conntracks[dir][i][cur_state]]);
-
 	return sctp_conntracks[dir][i][cur_state];
 }

@@ -369,7 +352,7 @@ int nf_conntrack_sctp_packet(struct nf_conn *ct,
 	if (sh == NULL)
 		goto out;
 
-	if (do_basic_checks(ct, skb, dataoff, map) != 0)
+	if (do_basic_checks(ct, skb, dataoff, map, state) != 0)
 		goto out;
 
 	if (!nf_ct_is_confirmed(ct)) {

@@ -392,7 +375,9 @@ int nf_conntrack_sctp_packet(struct nf_conn *ct,
 	    !test_bit(SCTP_CID_HEARTBEAT, map) &&
 	    !test_bit(SCTP_CID_HEARTBEAT_ACK, map) &&
 	    sh->vtag != ct->proto.sctp.vtag[dir]) {
-		pr_debug("Verification tag check failed\n");
+		nf_ct_l4proto_log_invalid(skb, ct, state,
+					  "verification tag check failed %x vs %x for dir %d",
+					  sh->vtag, ct->proto.sctp.vtag[dir], dir);
 		goto out;
 	}

@@ -470,9 +455,10 @@ int nf_conntrack_sctp_packet(struct nf_conn *ct,
 
 		/* Invalid */
 		if (new_state == SCTP_CONNTRACK_MAX) {
-			pr_debug("nf_conntrack_sctp: Invalid dir=%i ctype=%u "
-				 "conntrack=%u\n",
-				 dir, sch->type, old_state);
+			nf_ct_l4proto_log_invalid(skb, ct, state,
+						  "Invalid, old_state %d, dir %d, type %d",
+						  old_state, dir, sch->type);
+
 			goto out_unlock;
 		}

Signature · 1 line

2.53.0