From 35dbc9abd8da820007391b707bd2c1a9c99ee67d Mon Sep 17 00:00:00 2001 From: Chuang Wang nashuiliang@gmail.com Date: Tue, 4 Nov 2025 02:52:11 +0000 Subject: [PATCH net] ipv4: route: Prevent rt_bind_exception() from rebinding stale fnhe
A race condition exists between fnhe_remove_oldest() and rt_bind_exception() where a fnhe that is scheduled for removal can be rebound to a new dst.
The issue occurs when fnhe_remove_oldest() selects an fnhe (fnheX) for deletion, but before it can be flushed and freed via RCU, CPU 0 enters rt_bind_exception() and attempts to reuse the entry.
CPU 0 CPU 1 __mkroute_output() find_exception() [fnheX] update_or_create_fnhe() fnhe_remove_oldest() [fnheX] rt_bind_exception() [bind dst] RCU callback [fnheX freed, dst leak]
If rt_bind_exception() successfully binds fnheX to a new dst, the newly bound dst will never be properly freed because fnheX will soon be released by the RCU callback, leading to a permanent reference count leak on the old dst and the device.
This issue manifests as a device reference count leak and a warning in dmesg when unregistering the net device:
unregister_netdevice: waiting for ethX to become free. Usage count = N
Fix this race by clearing 'oldest->fnhe_daddr' before calling fnhe_flush_routes(). Since rt_bind_exception() checks this field, setting it to zero prevents the stale fnhe from being reused and bound to a new dst just before it is freed.
Cc: stable@vger.kernel.org Fixes: 67d6d681e15b ("ipv4: make exception cache less predictible") Signed-off-by: Chuang Wang nashuiliang@gmail.com --- net/ipv4/route.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 6d27d3610c1c..b549d6a57307 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -607,6 +607,11 @@ static void fnhe_remove_oldest(struct fnhe_hash_bucket *hash) oldest_p = fnhe_p; } } + + /* Clear oldest->fnhe_daddr to prevent this fnhe from being + * rebound with new dsts in rt_bind_exception(). + */ + oldest->fnhe_daddr = 0; fnhe_flush_routes(oldest); *oldest_p = oldest->fnhe_next; kfree_rcu(oldest, rcu); --
On Tue, Nov 04, 2025 at 11:09:08AM +0800, chuang wrote:
From 35dbc9abd8da820007391b707bd2c1a9c99ee67d Mon Sep 17 00:00:00 2001 From: Chuang Wang nashuiliang@gmail.com Date: Tue, 4 Nov 2025 02:52:11 +0000 Subject: [PATCH net] ipv4: route: Prevent rt_bind_exception() from rebinding stale fnhe
I'm unable to apply the patch:
$ b4 am -o - CACueBy7yNo4jq4HbiLXn0ez14w8CUTtTpPHmpSB-Ou6jhhNypA@mail.gmail.com | git am [...] Applying: ipv4: route: Prevent rt_bind_exception() from rebinding stale fnhe error: corrupt patch at line 10 Patch failed at 0001 ipv4: route: Prevent rt_bind_exception() from rebinding stale fnhe
Did you use git send-email?
A race condition exists between fnhe_remove_oldest() and rt_bind_exception() where a fnhe that is scheduled for removal can be rebound to a new dst.
The issue occurs when fnhe_remove_oldest() selects an fnhe (fnheX) for deletion, but before it can be flushed and freed via RCU, CPU 0 enters rt_bind_exception() and attempts to reuse the entry.
CPU 0 CPU 1 __mkroute_output() find_exception() [fnheX] update_or_create_fnhe() fnhe_remove_oldest() [fnheX] rt_bind_exception() [bind dst] RCU callback [fnheX freed, dst leak]
If rt_bind_exception() successfully binds fnheX to a new dst, the newly bound dst will never be properly freed because fnheX will soon be released by the RCU callback, leading to a permanent reference count leak on the old dst and the device.
This issue manifests as a device reference count leak and a warning in dmesg when unregistering the net device:
unregister_netdevice: waiting for ethX to become free. Usage count = N
Can you say more about how you debugged this? It seems like a very rare race condition. I expect netdevice_tracker to only show that a dst entry took a reference on the net device, but it wouldn't show who took a reference on the dst entry.
Fix this race by clearing 'oldest->fnhe_daddr' before calling fnhe_flush_routes(). Since rt_bind_exception() checks this field, setting it to zero prevents the stale fnhe from being reused and bound to a new dst just before it is freed.
Seems safe given that both fnhe_remove_oldest() and rt_bind_exception() access 'fnhe_daddr' while holding 'fnhe_lock'. Same trick was used in commit ee60ad219f5c ("route: set the deleted fnhe fnhe_daddr to 0 in ip_del_fnhe to fix a race").
Cc: stable@vger.kernel.org Fixes: 67d6d681e15b ("ipv4: make exception cache less predictible") Signed-off-by: Chuang Wang nashuiliang@gmail.com
net/ipv4/route.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 6d27d3610c1c..b549d6a57307 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -607,6 +607,11 @@ static void fnhe_remove_oldest(struct fnhe_hash_bucket *hash) oldest_p = fnhe_p; } }
/* Clear oldest->fnhe_daddr to prevent this fnhe from being* rebound with new dsts in rt_bind_exception().*/oldest->fnhe_daddr = 0; fnhe_flush_routes(oldest); *oldest_p = oldest->fnhe_next; kfree_rcu(oldest, rcu);--
On Mon, Nov 3, 2025 at 7:09 PM chuang nashuiliang@gmail.com wrote:
From 35dbc9abd8da820007391b707bd2c1a9c99ee67d Mon Sep 17 00:00:00 2001 From: Chuang Wang nashuiliang@gmail.com Date: Tue, 4 Nov 2025 02:52:11 +0000 Subject: [PATCH net] ipv4: route: Prevent rt_bind_exception() from rebinding stale fnhe
A race condition exists between fnhe_remove_oldest() and rt_bind_exception() where a fnhe that is scheduled for removal can be rebound to a new dst.
The issue occurs when fnhe_remove_oldest() selects an fnhe (fnheX) for deletion, but before it can be flushed and freed via RCU, CPU 0 enters rt_bind_exception() and attempts to reuse the entry.
CPU 0 CPU 1 __mkroute_output() find_exception() [fnheX] update_or_create_fnhe() fnhe_remove_oldest() [fnheX] rt_bind_exception() [bind dst] RCU callback [fnheX freed, dst leak]
If rt_bind_exception() successfully binds fnheX to a new dst, the newly bound dst will never be properly freed because fnheX will soon be released by the RCU callback, leading to a permanent reference count leak on the old dst and the device.
This issue manifests as a device reference count leak and a warning in dmesg when unregistering the net device:
unregister_netdevice: waiting for ethX to become free. Usage count = N
Fix this race by clearing 'oldest->fnhe_daddr' before calling fnhe_flush_routes(). Since rt_bind_exception() checks this field, setting it to zero prevents the stale fnhe from being reused and bound to a new dst just before it is freed.
Cc: stable@vger.kernel.org Fixes: 67d6d681e15b ("ipv4: make exception cache less predictible")
I do not see how this commit added the bug you are looking at ?
Signed-off-by: Chuang Wang nashuiliang@gmail.com
net/ipv4/route.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 6d27d3610c1c..b549d6a57307 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -607,6 +607,11 @@ static void fnhe_remove_oldest(struct fnhe_hash_bucket *hash) oldest_p = fnhe_p; } }
/* Clear oldest->fnhe_daddr to prevent this fnhe from being* rebound with new dsts in rt_bind_exception().*/oldest->fnhe_daddr = 0; fnhe_flush_routes(oldest); *oldest_p = oldest->fnhe_next; kfree_rcu(oldest, rcu);--
On Wed, Nov 05, 2025 at 06:26:22AM -0800, Eric Dumazet wrote:
On Mon, Nov 3, 2025 at 7:09 PM chuang nashuiliang@gmail.com wrote:
From 35dbc9abd8da820007391b707bd2c1a9c99ee67d Mon Sep 17 00:00:00 2001 From: Chuang Wang nashuiliang@gmail.com Date: Tue, 4 Nov 2025 02:52:11 +0000 Subject: [PATCH net] ipv4: route: Prevent rt_bind_exception() from rebinding stale fnhe
A race condition exists between fnhe_remove_oldest() and rt_bind_exception() where a fnhe that is scheduled for removal can be rebound to a new dst.
The issue occurs when fnhe_remove_oldest() selects an fnhe (fnheX) for deletion, but before it can be flushed and freed via RCU, CPU 0 enters rt_bind_exception() and attempts to reuse the entry.
CPU 0 CPU 1 __mkroute_output() find_exception() [fnheX] update_or_create_fnhe() fnhe_remove_oldest() [fnheX] rt_bind_exception() [bind dst] RCU callback [fnheX freed, dst leak]
If rt_bind_exception() successfully binds fnheX to a new dst, the newly bound dst will never be properly freed because fnheX will soon be released by the RCU callback, leading to a permanent reference count leak on the old dst and the device.
This issue manifests as a device reference count leak and a warning in dmesg when unregistering the net device:
unregister_netdevice: waiting for ethX to become free. Usage count = N
Fix this race by clearing 'oldest->fnhe_daddr' before calling fnhe_flush_routes(). Since rt_bind_exception() checks this field, setting it to zero prevents the stale fnhe from being reused and bound to a new dst just before it is freed.
Cc: stable@vger.kernel.org Fixes: 67d6d681e15b ("ipv4: make exception cache less predictible")
I do not see how this commit added the bug you are looking at ?
Not the author, but my understanding is that the issue is that an exception entry which is queued for deletion allows a dst entry to be bound to it. As such, nobody will ever release the reference from the dst entry and the associated net device.
Before 67d6d681e15b, exception entries were only queued for deletion by ip_del_fnhe() and it prevented dst entries from binding themselves to the deleted exception entry by clearing 'fnhe->fnhe_daddr' which is checked in rt_bind_exception(). See ee60ad219f5c7.
67d6d681e15b added another point in the code that queues exception entries for deletion, but without clearing 'fnhe->fnhe_daddr' first. Therefore, it added another instance of the bug that was fixed in ee60ad219f5c7.
Signed-off-by: Chuang Wang nashuiliang@gmail.com
net/ipv4/route.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 6d27d3610c1c..b549d6a57307 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -607,6 +607,11 @@ static void fnhe_remove_oldest(struct fnhe_hash_bucket *hash) oldest_p = fnhe_p; } }
/* Clear oldest->fnhe_daddr to prevent this fnhe from being* rebound with new dsts in rt_bind_exception().*/oldest->fnhe_daddr = 0; fnhe_flush_routes(oldest); *oldest_p = oldest->fnhe_next; kfree_rcu(oldest, rcu);--
On Wed, Nov 5, 2025 at 7:34 AM Ido Schimmel idosch@idosch.org wrote:
On Wed, Nov 05, 2025 at 06:26:22AM -0800, Eric Dumazet wrote:
On Mon, Nov 3, 2025 at 7:09 PM chuang nashuiliang@gmail.com wrote:
From 35dbc9abd8da820007391b707bd2c1a9c99ee67d Mon Sep 17 00:00:00 2001 From: Chuang Wang nashuiliang@gmail.com Date: Tue, 4 Nov 2025 02:52:11 +0000 Subject: [PATCH net] ipv4: route: Prevent rt_bind_exception() from rebinding stale fnhe
A race condition exists between fnhe_remove_oldest() and rt_bind_exception() where a fnhe that is scheduled for removal can be rebound to a new dst.
The issue occurs when fnhe_remove_oldest() selects an fnhe (fnheX) for deletion, but before it can be flushed and freed via RCU, CPU 0 enters rt_bind_exception() and attempts to reuse the entry.
CPU 0 CPU 1 __mkroute_output() find_exception() [fnheX] update_or_create_fnhe() fnhe_remove_oldest() [fnheX] rt_bind_exception() [bind dst] RCU callback [fnheX freed, dst leak]
If rt_bind_exception() successfully binds fnheX to a new dst, the newly bound dst will never be properly freed because fnheX will soon be released by the RCU callback, leading to a permanent reference count leak on the old dst and the device.
This issue manifests as a device reference count leak and a warning in dmesg when unregistering the net device:
unregister_netdevice: waiting for ethX to become free. Usage count = N
Fix this race by clearing 'oldest->fnhe_daddr' before calling fnhe_flush_routes(). Since rt_bind_exception() checks this field, setting it to zero prevents the stale fnhe from being reused and bound to a new dst just before it is freed.
Cc: stable@vger.kernel.org Fixes: 67d6d681e15b ("ipv4: make exception cache less predictible")
I do not see how this commit added the bug you are looking at ?
Not the author, but my understanding is that the issue is that an exception entry which is queued for deletion allows a dst entry to be bound to it. As such, nobody will ever release the reference from the dst entry and the associated net device.
Before 67d6d681e15b, exception entries were only queued for deletion by ip_del_fnhe() and it prevented dst entries from binding themselves to the deleted exception entry by clearing 'fnhe->fnhe_daddr' which is checked in rt_bind_exception(). See ee60ad219f5c7.
67d6d681e15b added another point in the code that queues exception entries for deletion, but without clearing 'fnhe->fnhe_daddr' first. Therefore, it added another instance of the bug that was fixed in ee60ad219f5c7.
Thanks for the clarification.
Thanks, your analysis is excellent and makes perfect sense. I can briefly describe the issue.
This problem took quite some time to analyze overall — we enabled netdev refcnt, added dst tracepoints, and eventually captured a race condition between fnhe deletion and rt_bind_exception.
In our environment, we use the sit driver(ip tunnel). During the xmit path, it records the PMTU for each destination, creating or updating fnhe entries (even when the MTU is already appropriate). Because there are many data flows, the sit driver updates PMTU very frequently, which leads to the race condition mentioned above.
Sorry for the brief summary — I’ll provide a more detailed explanation later, along with the patch verification method.
On Wed, Nov 5, 2025 at 23:34 Ido Schimmel idosch@idosch.org wrote:
On Wed, Nov 05, 2025 at 06:26:22AM -0800, Eric Dumazet wrote:
On Mon, Nov 3, 2025 at 7:09 PM chuang nashuiliang@gmail.com wrote:
From 35dbc9abd8da820007391b707bd2c1a9c99ee67d Mon Sep 17 00:00:00 2001 From: Chuang Wang nashuiliang@gmail.com Date: Tue, 4 Nov 2025 02:52:11 +0000 Subject: [PATCH net] ipv4: route: Prevent rt_bind_exception() from rebinding stale fnhe
A race condition exists between fnhe_remove_oldest() and rt_bind_exception() where a fnhe that is scheduled for removal can be rebound to a new dst.
The issue occurs when fnhe_remove_oldest() selects an fnhe (fnheX) for deletion, but before it can be flushed and freed via RCU, CPU 0 enters rt_bind_exception() and attempts to reuse the entry.
CPU 0 CPU 1 __mkroute_output() find_exception() [fnheX] update_or_create_fnhe() fnhe_remove_oldest() [fnheX] rt_bind_exception() [bind dst] RCU callback [fnheX freed, dst leak]
If rt_bind_exception() successfully binds fnheX to a new dst, the newly bound dst will never be properly freed because fnheX will soon be released by the RCU callback, leading to a permanent reference count leak on the old dst and the device.
This issue manifests as a device reference count leak and a warning in dmesg when unregistering the net device:
unregister_netdevice: waiting for ethX to become free. Usage count = N
Fix this race by clearing 'oldest->fnhe_daddr' before calling fnhe_flush_routes(). Since rt_bind_exception() checks this field, setting it to zero prevents the stale fnhe from being reused and bound to a new dst just before it is freed.
Cc: stable@vger.kernel.org Fixes: 67d6d681e15b ("ipv4: make exception cache less predictible")
I do not see how this commit added the bug you are looking at ?
Not the author, but my understanding is that the issue is that an exception entry which is queued for deletion allows a dst entry to be bound to it. As such, nobody will ever release the reference from the dst entry and the associated net device.
Before 67d6d681e15b, exception entries were only queued for deletion by ip_del_fnhe() and it prevented dst entries from binding themselves to the deleted exception entry by clearing 'fnhe->fnhe_daddr' which is checked in rt_bind_exception(). See ee60ad219f5c7.
67d6d681e15b added another point in the code that queues exception entries for deletion, but without clearing 'fnhe->fnhe_daddr' first. Therefore, it added another instance of the bug that was fixed in ee60ad219f5c7.
Signed-off-by: Chuang Wang nashuiliang@gmail.com
net/ipv4/route.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 6d27d3610c1c..b549d6a57307 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -607,6 +607,11 @@ static void fnhe_remove_oldest(struct fnhe_hash_bucket *hash) oldest_p = fnhe_p; } }
/* Clear oldest->fnhe_daddr to prevent this fnhe from being* rebound with new dsts in rt_bind_exception().*/oldest->fnhe_daddr = 0; fnhe_flush_routes(oldest); *oldest_p = oldest->fnhe_next; kfree_rcu(oldest, rcu);--
Thanks for reviewing the patch. I'm providing the detailed analysis and debugging traces below to confirm the root cause and exact location of the reference count leak.
1. Environment and Symptom
The issue was consistently reproduced when routing TCP traffic through a Software IP Tunnel interface (sit0). The traffic flow is:
APP -> sit0 (IP tunnel) -> outside
This leads to a reference count leak that prevents the device from being freed during unregistration, resulting in the kernel log warning:
unregister_netdevice: waiting for sit0 to become free. Usage count = N
2. Enable refcnt_tracer
Live-crash analysis identified a stale dst entry retaining a reference to sit0. With CONFIG_NET_DEV_REFCNT_TRACKER enabled, the allocation stack for the leaked reference was identified:
[1279559.416854] leaked reference. [1279559.416955] dst_init+0x48/0x100 [1279559.416965] dst_alloc+0x66/0xd0 [1279559.416966] rt_dst_alloc+0x3c/0xd0 [1279559.416974] ip_route_output_key_hash_rcu+0x1d7/0x940 [1279559.416978] ip_route_output_key_hash+0x6d/0xa0 [1279559.416979] ip_route_output_flow+0x1f/0x70 [1279559.416980] __ip_queue_xmit+0x415/0x480 [1279559.416984] ip_queue_xmit+0x15/0x20 [1279559.416986] __tcp_transmit_skb+0xad4/0xc50
3. Pinpointing the Unmatched dst_hold()
To pinpoint the specific reference not released, we added tracepoints to all dst_hold/put functions and used eBPF to record the full lifecycle. The tracing identified a hold operation with the following call stack:
do_trace_dst_entry_inc+0x45 rt_set_nexthop.constprop.0+0x376 /* <<<<<<<<<<<<<<<<<<<< HERE */ __mkroute_output+0x2B7 ip_route_output_key_hash_rcu+0xBD ip_route_output_key_hash+0x6D ip_route_output_flow+0x1F inet_sk_rebuild_header+0x19C __tcp_retransmit_skb+0x7E tcp_retransmit_skb+0x19 tcp_retransmit_timer+0x3DF
The address rt_set_nexthop.constprop.0+0x376 corresponds to the dst_hold() call inside rt_bind_exception().
4. Root Cause Analysis
The sit driver's packet transmission path calls: sit_tunnel_xmit() -> ... -> update_or_create_fnhe(), which lead to fnhe_remove_oldest() being called to delete entries exceeding the FNHE_RECLAIM_DEPTH+random.
The race window is between fnhe_remove_oldest() selecting fnheX for deletion and the subsequent kfree_rcu(). During this time, the concurrent path's __mkroute_output() -> find_exception() can fetch the soon-to-be-deleted fnheX, and rt_bind_exception() then binds it with a new dst using a dst_hold(). When the original fnheX is freed via RCU, the dst reference remains permanently leaked.
5. Fix Validation with eBPF
The patch mitigates this by zeroing fnhe_daddr before the RCU-protected deletion steps. This prevents rt_bind_exception() from attempting to reuse the entry. The fix was validated by probing the rt_bind_exception path (which in my environment is optimized to rt_set_nexthop.constprop.0) to catch any zeroed but active FNHEs being processed:
bpftrace -e 'kprobe:rt_set_nexthop.constprop.0 { $rt = (struct rtable *)arg0; $fnhe = (struct fib_nh_exception *)arg3; $fi = (struct flowi *)arg4;
/* Check for an FNHE that is marked for deletion (daddr == 0) * but is still visible/valid (fnhe_expires != 0 and not expired). */ if ($fi != 0 && $fnhe != 0 && $fnhe->fnhe_daddr == 0 && $fnhe->fnhe_expires != 0 && $fnhe->fnhe_expires >= jiffies) { printf("rt: %llx, dev: %s, will leak before this patch\n", $rt, $rt->dst.dev->name); } }'
On Thu, Nov 6, 2025 at 8:31 AM chuang nashuiliang@gmail.com wrote:
Thanks, your analysis is excellent and makes perfect sense. I can briefly describe the issue.
This problem took quite some time to analyze overall — we enabled netdev refcnt, added dst tracepoints, and eventually captured a race condition between fnhe deletion and rt_bind_exception.
In our environment, we use the sit driver(ip tunnel). During the xmit path, it records the PMTU for each destination, creating or updating fnhe entries (even when the MTU is already appropriate). Because there are many data flows, the sit driver updates PMTU very frequently, which leads to the race condition mentioned above.
Sorry for the brief summary — I’ll provide a more detailed explanation later, along with the patch verification method.
On Wed, Nov 5, 2025 at 23:34 Ido Schimmel idosch@idosch.org wrote:
On Wed, Nov 05, 2025 at 06:26:22AM -0800, Eric Dumazet wrote:
On Mon, Nov 3, 2025 at 7:09 PM chuang nashuiliang@gmail.com wrote:
From 35dbc9abd8da820007391b707bd2c1a9c99ee67d Mon Sep 17 00:00:00 2001 From: Chuang Wang nashuiliang@gmail.com Date: Tue, 4 Nov 2025 02:52:11 +0000 Subject: [PATCH net] ipv4: route: Prevent rt_bind_exception() from rebinding stale fnhe
A race condition exists between fnhe_remove_oldest() and rt_bind_exception() where a fnhe that is scheduled for removal can be rebound to a new dst.
The issue occurs when fnhe_remove_oldest() selects an fnhe (fnheX) for deletion, but before it can be flushed and freed via RCU, CPU 0 enters rt_bind_exception() and attempts to reuse the entry.
CPU 0 CPU 1 __mkroute_output() find_exception() [fnheX] update_or_create_fnhe() fnhe_remove_oldest() [fnheX] rt_bind_exception() [bind dst] RCU callback [fnheX freed, dst leak]
If rt_bind_exception() successfully binds fnheX to a new dst, the newly bound dst will never be properly freed because fnheX will soon be released by the RCU callback, leading to a permanent reference count leak on the old dst and the device.
This issue manifests as a device reference count leak and a warning in dmesg when unregistering the net device:
unregister_netdevice: waiting for ethX to become free. Usage count = N
Fix this race by clearing 'oldest->fnhe_daddr' before calling fnhe_flush_routes(). Since rt_bind_exception() checks this field, setting it to zero prevents the stale fnhe from being reused and bound to a new dst just before it is freed.
Cc: stable@vger.kernel.org Fixes: 67d6d681e15b ("ipv4: make exception cache less predictible")
I do not see how this commit added the bug you are looking at ?
Not the author, but my understanding is that the issue is that an exception entry which is queued for deletion allows a dst entry to be bound to it. As such, nobody will ever release the reference from the dst entry and the associated net device.
Before 67d6d681e15b, exception entries were only queued for deletion by ip_del_fnhe() and it prevented dst entries from binding themselves to the deleted exception entry by clearing 'fnhe->fnhe_daddr' which is checked in rt_bind_exception(). See ee60ad219f5c7.
67d6d681e15b added another point in the code that queues exception entries for deletion, but without clearing 'fnhe->fnhe_daddr' first. Therefore, it added another instance of the bug that was fixed in ee60ad219f5c7.
Signed-off-by: Chuang Wang nashuiliang@gmail.com
net/ipv4/route.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 6d27d3610c1c..b549d6a57307 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -607,6 +607,11 @@ static void fnhe_remove_oldest(struct fnhe_hash_bucket *hash) oldest_p = fnhe_p; } }
/* Clear oldest->fnhe_daddr to prevent this fnhe from being* rebound with new dsts in rt_bind_exception().*/oldest->fnhe_daddr = 0; fnhe_flush_routes(oldest); *oldest_p = oldest->fnhe_next; kfree_rcu(oldest, rcu);--
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