FAILED: patch "[PATCH] xfrm: save input state data before secpath resets" failed to apply to 6.6-stable tree

PATCH New [email protected] 2 participants 2 messages Sep 22

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[email protected]

author maintainer

2026-09-22 09:42 UTC #0 lore raw

The patch below does not apply to the 6.6-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-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x 3cf5cdecd99c9c186a5ea518d93bbf3045b6e3aa
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026092227-quarry-haggler-ba0c@gregkh' --subject-prefix 'PATCH 6.6.y' 'HEAD^..'

Possible dependencies:

thanks,

greg k-h

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

From 3cf5cdecd99c9c186a5ea518d93bbf3045b6e3aa Mon Sep 17 00:00:00 2001
From: Zhiling Zou <[email protected]>
Date: Sat, 29 Aug 2026 17:24:24 +0800
Subject: [PATCH] xfrm: save input state data before secpath resets

xfrm_input() stores the current xfrm_state in the skb secpath while it continues receive-side processing. Some input paths can reset that secpath before xfrm_input() has finished dereferencing the state.

Receive callback users such as VTI and XFRM interfaces can reset the secpath. The VTI receive path does so before checking whether the packet crosses network namespaces, while the XFRM interface path does so only for cross-network-namespace packets. The XFRM_MAX_DEPTH error path can also reset the secpath before the final drop callback reports the current state's protocol.

If secpath_reset() drops the last state reference while the state is concurrently deleted, xfrm_input() can still dereference the freed state when selecting transport_finish() or reporting the drop callback protocol.

Save the state protocol on the stack while the state is still valid, and use the already saved address family for transport_finish(). A larval XFRM_STATE_ACQ state has no type, so retain nexthdr as its protocol. This preserves the existing drop-path fallback while avoiding the post-reset state dereferences without adding an extra state reference to every received packet.

Fixes df3893c176e9 ("vti: Update the ipv4 side to use it's own receive hook.")

Cc [email protected]

Reported-by Vega <[email protected]>

Signed-off-by Zhiling Zou <[email protected]>

Signed-off-by Steffen Klassert <[email protected]>

net/xfrm/xfrm_input.c +8 -3

index 8f6109eada7e..5ed87d51392a 100644
@@ -474,6 +474,7 @@ int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type)
 	struct xfrm_state *x = NULL;
 	xfrm_address_t *daddr;
 	u32 mark = skb->mark;
+	u8 xfrm_proto = nexthdr;
 	unsigned int family = AF_UNSPEC;
 	int decaps = 0;
 	int async = 0;

@@ -485,6 +486,7 @@ int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type)
 	if (encap_type < 0 || (xo && (xo->flags & XFRM_GRO || encap_type == 0 ||
 				      encap_type == UDP_ENCAP_ESPINUDP))) {
 		x = xfrm_input_state(skb);
+		xfrm_proto = x->type ? x->type->proto : nexthdr;
 
 		if (unlikely(x->km.state != XFRM_STATE_VALID)) {
 			if (x->km.state == XFRM_STATE_ACQ)

@@ -592,11 +594,13 @@ int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type)
 
 		x = xfrm_input_state_lookup(net, mark, daddr, spi, nexthdr, family);
 		if (x == NULL) {
+			xfrm_proto = nexthdr;
 			secpath_reset(skb);
 			XFRM_INC_STATS(net, LINUX_MIB_XFRMINNOSTATES);
 			xfrm_audit_state_notfound(skb, family, spi, seq);
 			goto drop;
 		}
+		xfrm_proto = x->type ? x->type->proto : nexthdr;
 
 		if (unlikely(x->dir && x->dir != XFRM_SA_DIR_IN)) {
 			secpath_reset(skb);

@@ -604,6 +608,7 @@ int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type)
 			xfrm_audit_state_notfound(skb, family, spi, seq);
 			xfrm_state_put(x);
 			x = NULL;
+			xfrm_proto = nexthdr;
 			goto drop;
 		}

@@ -728,7 +733,7 @@ int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type)
 	} while (!err);
 
 	rcu_read_lock();
-	err = xfrm_rcv_cb(skb, family, x->type->proto, 0);
+	err = xfrm_rcv_cb(skb, family, xfrm_proto, 0);
 	if (err) {
 		rcu_read_unlock();
 		goto drop;

@@ -753,7 +758,7 @@ int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type)
 			xfrm_gro = xo->flags & XFRM_GRO;
 
 		err = -EAFNOSUPPORT;
-		afinfo = xfrm_state_afinfo_get_rcu(x->props.family);
+		afinfo = xfrm_state_afinfo_get_rcu(family);
 		if (likely(afinfo))
 			err = afinfo->transport_finish(skb, xfrm_gro || async);
 		if (xfrm_gro) {

@@ -776,7 +781,7 @@ int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type)
 drop:
 	if (async)
 		dev_put(dev);
-	xfrm_rcv_cb(skb, family, x && x->type ? x->type->proto : nexthdr, -1);
+	xfrm_rcv_cb(skb, family, xfrm_proto, -1);
 	kfree_skb(skb);
 	return 0;
 }

Sasha Levin

maintainer

2026-09-22 17:51 UTC #1 lore raw

PATCH 1/1 xfrm: save input state data before secpath resets

From: Zhiling Zou <[email protected]>

[ Upstream commit 3cf5cdecd99c9c186a5ea518d93bbf3045b6e3aa ]

Fixes df3893c176e9 ("vti: Update the ipv4 side to use it's own receive hook.")

Cc [email protected]

Reported-by Vega <[email protected]>

Signed-off-by Zhiling Zou <[email protected]>

Signed-off-by Steffen Klassert <[email protected]>

[ omitted the protocol fallback assignment for the state-direction rejection branch absent in 6.6. ]

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

---
 net/xfrm/xfrm_input.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

net/xfrm/xfrm_input.c +7 -3

index 1483770f84564..26f2fd7e01da9 100644
@@ -462,6 +462,7 @@ int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type)
 	struct xfrm_state *x = NULL;
 	xfrm_address_t *daddr;
 	u32 mark = skb->mark;
+	u8 xfrm_proto = nexthdr;
 	unsigned int family = AF_UNSPEC;
 	int decaps = 0;
 	int async = 0;

@@ -472,6 +473,7 @@ int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type)
 
 	if (encap_type < 0 || (xo && (xo->flags & XFRM_GRO || encap_type == 0))) {
 		x = xfrm_input_state(skb);
+		xfrm_proto = x->type ? x->type->proto : nexthdr;
 
 		if (unlikely(x->km.state != XFRM_STATE_VALID)) {
 			if (x->km.state == XFRM_STATE_ACQ)

@@ -572,11 +574,13 @@ int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type)
 
 		x = xfrm_state_lookup(net, mark, daddr, spi, nexthdr, family);
 		if (x == NULL) {
+			xfrm_proto = nexthdr;
 			secpath_reset(skb);
 			XFRM_INC_STATS(net, LINUX_MIB_XFRMINNOSTATES);
 			xfrm_audit_state_notfound(skb, family, spi, seq);
 			goto drop;
 		}
+		xfrm_proto = x->type ? x->type->proto : nexthdr;
 
 		skb->mark = xfrm_smark_get(skb->mark, x);

@@ -693,7 +697,7 @@ int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type)
 		crypto_done = false;
 	} while (!err);
 
-	err = xfrm_rcv_cb(skb, family, x->type->proto, 0);
+	err = xfrm_rcv_cb(skb, family, xfrm_proto, 0);
 	if (err)
 		goto drop;

@@ -714,7 +718,7 @@ int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type)
 
 		err = -EAFNOSUPPORT;
 		rcu_read_lock();
-		afinfo = xfrm_state_afinfo_get_rcu(x->props.family);
+		afinfo = xfrm_state_afinfo_get_rcu(family);
 		if (likely(afinfo))
 			err = afinfo->transport_finish(skb, xfrm_gro || async);
 		rcu_read_unlock();

@@ -734,7 +738,7 @@ int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type)
 drop_unlock:
 	spin_unlock(&x->lock);
 drop:
-	xfrm_rcv_cb(skb, family, x && x->type ? x->type->proto : nexthdr, -1);
+	xfrm_rcv_cb(skb, family, xfrm_proto, -1);
 	kfree_skb(skb);
 	return 0;
 }

Signature · 1 line

2.53.0