[PATCH 6.12.y] xfrm: hold dev ref until after transport_finish NF_HOOK

[Simon Liebold <simonlie@amazon.de>]

From: Qi Tang <tpluszz77@gmail.com>

[ Upstream commit 1c428b03840094410c5fb6a5db30640486bbbfcb ]

After async crypto completes, xfrm_input_resume() calls dev_put()
immediately on re-entry before the skb reaches transport_finish.
The skb->dev pointer is then used inside NF_HOOK and its okfn,
which can race with device teardown.

Remove the dev_put from the async resumption entry and instead
drop the reference after the NF_HOOK call in transport_finish,
using a saved device pointer since NF_HOOK may consume the skb.
This covers NF_DROP, NF_QUEUE and NF_STOLEN paths that skip
the okfn.

For non-transport exits (decaps, gro, drop) and secondary
async return points, release the reference inline when
async is set.

Suggested-by: Florian Westphal <fw@strlen.de>
Fixes: acf568ee859f ("xfrm: Reinject transport-mode packets through tasklet")
Cc: stable@vger.kernel.org
Signed-off-by: Qi Tang <tpluszz77@gmail.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
[ net/xfrm/xfrm_input.c: dev_hold/dev_put are unconditional here rather
than inside !crypto_done as in mainline, and the dev_put in the
encap_type == -1 async-resumption block does not exist; adapted by
gating dev_put at resume: with if (!async), adding if (async) dev_put
at -EINPROGRESS return, gro_cells_receive paths, and drop label. ]
Signed-off-by: Simon Liebold <simonlie@amazon.de>
---
 net/ipv4/xfrm4_input.c |  5 ++++-
 net/ipv6/xfrm6_input.c |  5 ++++-
 net/xfrm/xfrm_input.c  | 14 ++++++++++++--
 3 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/net/ipv4/xfrm4_input.c b/net/ipv4/xfrm4_input.c
index 12a1a0f421956..adf21d6b6076c 100644
--- a/net/ipv4/xfrm4_input.c
+++ b/net/ipv4/xfrm4_input.c
@@ -50,6 +50,7 @@ int xfrm4_transport_finish(struct sk_buff *skb, int async)
 {
 	struct xfrm_offload *xo = xfrm_offload(skb);
 	struct iphdr *iph = ip_hdr(skb);
+	struct net_device *dev = skb->dev;
 
 	iph->protocol = XFRM_MODE_SKB_CB(skb)->protocol;
 
@@ -73,8 +74,10 @@ int xfrm4_transport_finish(struct sk_buff *skb, int async)
 	}
 
 	NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING,
-		dev_net(skb->dev), NULL, skb, skb->dev, NULL,
+		dev_net(dev), NULL, skb, dev, NULL,
 		xfrm4_rcv_encap_finish);
+	if (async)
+		dev_put(dev);
 	return 0;
 }
 
diff --git a/net/ipv6/xfrm6_input.c b/net/ipv6/xfrm6_input.c
index 9005fc156a20e..699a001ac1662 100644
--- a/net/ipv6/xfrm6_input.c
+++ b/net/ipv6/xfrm6_input.c
@@ -43,6 +43,7 @@ static int xfrm6_transport_finish2(struct net *net, struct sock *sk,
 int xfrm6_transport_finish(struct sk_buff *skb, int async)
 {
 	struct xfrm_offload *xo = xfrm_offload(skb);
+	struct net_device *dev = skb->dev;
 	int nhlen = -skb_network_offset(skb);
 
 	skb_network_header(skb)[IP6CB(skb)->nhoff] =
@@ -68,8 +69,10 @@ int xfrm6_transport_finish(struct sk_buff *skb, int async)
 	}
 
 	NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING,
-		dev_net(skb->dev), NULL, skb, skb->dev, NULL,
+		dev_net(dev), NULL, skb, dev, NULL,
 		xfrm6_transport_finish2);
+	if (async)
+		dev_put(dev);
 	return 0;
 }
 
diff --git a/net/xfrm/xfrm_input.c b/net/xfrm/xfrm_input.c
index 841a60a6fbfea..028cd88946487 100644
--- a/net/xfrm/xfrm_input.c
+++ b/net/xfrm/xfrm_input.c
@@ -645,10 +645,14 @@ int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type)
 		else
 			nexthdr = x->type->input(x, skb);
 
-		if (nexthdr == -EINPROGRESS)
+		if (nexthdr == -EINPROGRESS) {
+			if (async)
+				dev_put(skb->dev);
 			return 0;
+		}
 resume:
-		dev_put(skb->dev);
+		if (!async)
+			dev_put(skb->dev);
 
 		spin_lock(&x->lock);
 		if (nexthdr < 0) {
@@ -716,6 +720,8 @@ int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type)
 			sp->olen = 0;
 		if (skb_valid_dst(skb))
 			skb_dst_drop(skb);
+		if (async)
+			dev_put(skb->dev);
 		gro_cells_receive(&gro_cells, skb);
 		return 0;
 	} else {
@@ -735,6 +741,8 @@ int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type)
 				sp->olen = 0;
 			if (skb_valid_dst(skb))
 				skb_dst_drop(skb);
+			if (async)
+				dev_put(skb->dev);
 			gro_cells_receive(&gro_cells, skb);
 			return err;
 		}
@@ -745,6 +753,8 @@ int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type)
 drop_unlock:
 	spin_unlock(&x->lock);
 drop:
+	if (async)
+		dev_put(skb->dev);
 	xfrm_rcv_cb(skb, family, x && x->type ? x->type->proto : nexthdr, -1);
 	kfree_skb(skb);
 	return 0;
-- 
2.50.1




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