From: Bernard Pidoux <bernard.f6bvp@gmail.com>
To: netdev@vger.kernel.org
Cc: linux-hams@vger.kernel.org, linux-kernel@vger.kernel.org,
davem@davemloft.net, edumazet@google.com, kuba@kernel.org,
pabeni@redhat.com, horms@kernel.org,
Bernard Pidoux <bernard.f6bvp@gmail.com>
Subject: [PATCH net 4/5] rose: clear neighbour pointer after rose_neigh_put() in state machines
Date: Sun, 26 Apr 2026 16:43:04 +0200 [thread overview]
Message-ID: <20260426144305.984349-5-bernard.f6bvp@gmail.com> (raw)
In-Reply-To: <20260426144305.984349-1-bernard.f6bvp@gmail.com>
After calling rose_neigh_put() in rose_state1_machine() through
rose_state5_machine(), rose->neighbour was left pointing at the
potentially freed neighbour structure. A subsequent timer expiry or
concurrent teardown path could dereference the stale pointer, causing
a use-after-free.
Set rose->neighbour to NULL immediately after each rose_neigh_put()
call in the state machine functions.
Fixes: d860d1faa6b2 ("net: rose: convert 'use' field to refcount_t")
Tested-by: Bernard Pidoux <bernard.f6bvp@gmail.com>
Signed-off-by: Bernard Pidoux <bernard.f6bvp@gmail.com>
---
net/rose/rose_in.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/net/rose/rose_in.c b/net/rose/rose_in.c
index 0276b393f0e5..622527f1354f 100644
--- a/net/rose/rose_in.c
+++ b/net/rose/rose_in.c
@@ -57,6 +57,7 @@ static int rose_state1_machine(struct sock *sk, struct sk_buff *skb, int framety
rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
rose_disconnect(sk, ECONNREFUSED, skb->data[3], skb->data[4]);
rose_neigh_put(rose->neighbour);
+ rose->neighbour = NULL;
break;
default:
@@ -80,11 +81,13 @@ static int rose_state2_machine(struct sock *sk, struct sk_buff *skb, int framety
rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
rose_neigh_put(rose->neighbour);
+ rose->neighbour = NULL;
break;
case ROSE_CLEAR_CONFIRMATION:
rose_disconnect(sk, 0, -1, -1);
rose_neigh_put(rose->neighbour);
+ rose->neighbour = NULL;
break;
default:
@@ -122,6 +125,7 @@ static int rose_state3_machine(struct sock *sk, struct sk_buff *skb, int framety
rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
rose_neigh_put(rose->neighbour);
+ rose->neighbour = NULL;
break;
case ROSE_RR:
@@ -235,6 +239,7 @@ static int rose_state4_machine(struct sock *sk, struct sk_buff *skb, int framety
rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
rose_neigh_put(rose->neighbour);
+ rose->neighbour = NULL;
break;
default:
@@ -255,6 +260,7 @@ static int rose_state5_machine(struct sock *sk, struct sk_buff *skb, int framety
rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
rose_neigh_put(rose_sk(sk)->neighbour);
+ rose_sk(sk)->neighbour = NULL;
}
return 0;
--
2.51.0
next prev parent reply other threads:[~2026-04-26 14:43 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-26 14:43 [PATCH net 0/5] rose: fix use-after-free and reference counting bugs Bernard Pidoux
2026-04-26 14:43 ` [PATCH net 1/5] rose: fix dev_put() leak in rose_loopback_timer() Bernard Pidoux
2026-04-26 14:43 ` [PATCH net 2/5] rose: hold loopback neighbour reference across timer callback Bernard Pidoux
2026-04-26 14:43 ` [PATCH net 3/5] rose: fix race between loopback timer and module removal Bernard Pidoux
2026-04-26 14:43 ` Bernard Pidoux [this message]
2026-04-26 14:43 ` [PATCH net 5/5] rose: guard rose_neigh_put() against NULL in timer expiry Bernard Pidoux
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