[PATCH net v2] bridge: mrp: reject zero test interval to avoid OOM panic

[PATCH net v2] bridge: mrp: reject zero test interval to avoid OOM panic

[Xiang Mei]

br_mrp_start_test() and br_mrp_start_in_test() accept the user-supplied
interval value from netlink without validation. When interval is 0,
usecs_to_jiffies(0) yields 0, causing the delayed work
(br_mrp_test_work_expired / br_mrp_in_test_work_expired) to reschedule
itself with zero delay. This creates a tight loop on system_percpu_wq
that allocates and transmits MRP test frames at maximum rate, exhausting
all system memory and causing a kernel panic via OOM deadlock.

The same zero-interval issue applies to br_mrp_start_in_test_parse()
for interconnect test frames.

Use NLA_POLICY_MIN(NLA_U32, 1) in the nla_policy tables for both
IFLA_BRIDGE_MRP_START_TEST_INTERVAL and
IFLA_BRIDGE_MRP_START_IN_TEST_INTERVAL, so zero is rejected at the
netlink attribute parsing layer before the value ever reaches the
workqueue scheduling code. This is consistent with how other bridge
subsystems (br_fdb, br_mst) enforce range constraints on netlink
attributes.

Fixes: 20f6a05ef635 ("bridge: mrp: Rework the MRP netlink interface")
Fixes: 7ab1748e4ce6 ("bridge: mrp: Extend MRP netlink interface for configuring MRP interconnect")
Reported-by: Weiming Shi <bestswngs@gmail.com>
Signed-off-by: Xiang Mei <xmei5@asu.edu>
---
 net/bridge/br_mrp_netlink.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/bridge/br_mrp_netlink.c b/net/bridge/br_mrp_netlink.c
index ce6f63c77cc0..86f0e75d6e34 100644
--- a/net/bridge/br_mrp_netlink.c
+++ b/net/bridge/br_mrp_netlink.c
@@ -196,7 +196,7 @@ static const struct nla_policy
 br_mrp_start_test_policy[IFLA_BRIDGE_MRP_START_TEST_MAX + 1] = {
 	[IFLA_BRIDGE_MRP_START_TEST_UNSPEC]	= { .type = NLA_REJECT },
 	[IFLA_BRIDGE_MRP_START_TEST_RING_ID]	= { .type = NLA_U32 },
-	[IFLA_BRIDGE_MRP_START_TEST_INTERVAL]	= { .type = NLA_U32 },
+	[IFLA_BRIDGE_MRP_START_TEST_INTERVAL]	= NLA_POLICY_MIN(NLA_U32, 1),
 	[IFLA_BRIDGE_MRP_START_TEST_MAX_MISS]	= { .type = NLA_U32 },
 	[IFLA_BRIDGE_MRP_START_TEST_PERIOD]	= { .type = NLA_U32 },
 	[IFLA_BRIDGE_MRP_START_TEST_MONITOR]	= { .type = NLA_U32 },
@@ -316,7 +316,7 @@ static const struct nla_policy
 br_mrp_start_in_test_policy[IFLA_BRIDGE_MRP_START_IN_TEST_MAX + 1] = {
 	[IFLA_BRIDGE_MRP_START_IN_TEST_UNSPEC]	= { .type = NLA_REJECT },
 	[IFLA_BRIDGE_MRP_START_IN_TEST_IN_ID]	= { .type = NLA_U32 },
-	[IFLA_BRIDGE_MRP_START_IN_TEST_INTERVAL]	= { .type = NLA_U32 },
+	[IFLA_BRIDGE_MRP_START_IN_TEST_INTERVAL]	= NLA_POLICY_MIN(NLA_U32, 1),
 	[IFLA_BRIDGE_MRP_START_IN_TEST_MAX_MISS]	= { .type = NLA_U32 },
 	[IFLA_BRIDGE_MRP_START_IN_TEST_PERIOD]	= { .type = NLA_U32 },
 };
-- 
2.43.0

Re: [PATCH net v2] bridge: mrp: reject zero test interval to avoid OOM panic

[Nikolay Aleksandrov]

On 28/03/2026 08:30, Xiang Mei wrote:
> br_mrp_start_test() and br_mrp_start_in_test() accept the user-supplied
> interval value from netlink without validation. When interval is 0,
> usecs_to_jiffies(0) yields 0, causing the delayed work
> (br_mrp_test_work_expired / br_mrp_in_test_work_expired) to reschedule
> itself with zero delay. This creates a tight loop on system_percpu_wq
> that allocates and transmits MRP test frames at maximum rate, exhausting
> all system memory and causing a kernel panic via OOM deadlock.
> 
> The same zero-interval issue applies to br_mrp_start_in_test_parse()
> for interconnect test frames.
> 
> Use NLA_POLICY_MIN(NLA_U32, 1) in the nla_policy tables for both
> IFLA_BRIDGE_MRP_START_TEST_INTERVAL and
> IFLA_BRIDGE_MRP_START_IN_TEST_INTERVAL, so zero is rejected at the
> netlink attribute parsing layer before the value ever reaches the
> workqueue scheduling code. This is consistent with how other bridge
> subsystems (br_fdb, br_mst) enforce range constraints on netlink
> attributes.
> 
> Fixes: 20f6a05ef635 ("bridge: mrp: Rework the MRP netlink interface")
> Fixes: 7ab1748e4ce6 ("bridge: mrp: Extend MRP netlink interface for configuring MRP interconnect")
> Reported-by: Weiming Shi <bestswngs@gmail.com>
> Signed-off-by: Xiang Mei <xmei5@asu.edu>
> ---
>   net/bridge/br_mrp_netlink.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/net/bridge/br_mrp_netlink.c b/net/bridge/br_mrp_netlink.c
> index ce6f63c77cc0..86f0e75d6e34 100644
> --- a/net/bridge/br_mrp_netlink.c
> +++ b/net/bridge/br_mrp_netlink.c
> @@ -196,7 +196,7 @@ static const struct nla_policy
>   br_mrp_start_test_policy[IFLA_BRIDGE_MRP_START_TEST_MAX + 1] = {
>   	[IFLA_BRIDGE_MRP_START_TEST_UNSPEC]	= { .type = NLA_REJECT },
>   	[IFLA_BRIDGE_MRP_START_TEST_RING_ID]	= { .type = NLA_U32 },
> -	[IFLA_BRIDGE_MRP_START_TEST_INTERVAL]	= { .type = NLA_U32 },
> +	[IFLA_BRIDGE_MRP_START_TEST_INTERVAL]	= NLA_POLICY_MIN(NLA_U32, 1),
>   	[IFLA_BRIDGE_MRP_START_TEST_MAX_MISS]	= { .type = NLA_U32 },
>   	[IFLA_BRIDGE_MRP_START_TEST_PERIOD]	= { .type = NLA_U32 },
>   	[IFLA_BRIDGE_MRP_START_TEST_MONITOR]	= { .type = NLA_U32 },
> @@ -316,7 +316,7 @@ static const struct nla_policy
>   br_mrp_start_in_test_policy[IFLA_BRIDGE_MRP_START_IN_TEST_MAX + 1] = {
>   	[IFLA_BRIDGE_MRP_START_IN_TEST_UNSPEC]	= { .type = NLA_REJECT },
>   	[IFLA_BRIDGE_MRP_START_IN_TEST_IN_ID]	= { .type = NLA_U32 },
> -	[IFLA_BRIDGE_MRP_START_IN_TEST_INTERVAL]	= { .type = NLA_U32 },
> +	[IFLA_BRIDGE_MRP_START_IN_TEST_INTERVAL]	= NLA_POLICY_MIN(NLA_U32, 1),
>   	[IFLA_BRIDGE_MRP_START_IN_TEST_MAX_MISS]	= { .type = NLA_U32 },
>   	[IFLA_BRIDGE_MRP_START_IN_TEST_PERIOD]	= { .type = NLA_U32 },
>   };

Alright, let's limit them :-)

Acked-by: Nikolay Aleksandrov <razor@blackwall.org>

Re: [PATCH net v2] bridge: mrp: reject zero test interval to avoid OOM panic

[Xiang Mei]

Thanks for the quick review.

On Fri, Mar 27, 2026 at 11:44 PM Nikolay Aleksandrov
<razor@blackwall.org> wrote:
>
> On 28/03/2026 08:30, Xiang Mei wrote:
> > br_mrp_start_test() and br_mrp_start_in_test() accept the user-supplied
> > interval value from netlink without validation. When interval is 0,
> > usecs_to_jiffies(0) yields 0, causing the delayed work
> > (br_mrp_test_work_expired / br_mrp_in_test_work_expired) to reschedule
> > itself with zero delay. This creates a tight loop on system_percpu_wq
> > that allocates and transmits MRP test frames at maximum rate, exhausting
> > all system memory and causing a kernel panic via OOM deadlock.
> >
> > The same zero-interval issue applies to br_mrp_start_in_test_parse()
> > for interconnect test frames.
> >
> > Use NLA_POLICY_MIN(NLA_U32, 1) in the nla_policy tables for both
> > IFLA_BRIDGE_MRP_START_TEST_INTERVAL and
> > IFLA_BRIDGE_MRP_START_IN_TEST_INTERVAL, so zero is rejected at the
> > netlink attribute parsing layer before the value ever reaches the
> > workqueue scheduling code. This is consistent with how other bridge
> > subsystems (br_fdb, br_mst) enforce range constraints on netlink
> > attributes.
> >
> > Fixes: 20f6a05ef635 ("bridge: mrp: Rework the MRP netlink interface")
> > Fixes: 7ab1748e4ce6 ("bridge: mrp: Extend MRP netlink interface for configuring MRP interconnect")
> > Reported-by: Weiming Shi <bestswngs@gmail.com>
> > Signed-off-by: Xiang Mei <xmei5@asu.edu>
> > ---
> >   net/bridge/br_mrp_netlink.c | 4 ++--
> >   1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/net/bridge/br_mrp_netlink.c b/net/bridge/br_mrp_netlink.c
> > index ce6f63c77cc0..86f0e75d6e34 100644
> > --- a/net/bridge/br_mrp_netlink.c
> > +++ b/net/bridge/br_mrp_netlink.c
> > @@ -196,7 +196,7 @@ static const struct nla_policy
> >   br_mrp_start_test_policy[IFLA_BRIDGE_MRP_START_TEST_MAX + 1] = {
> >       [IFLA_BRIDGE_MRP_START_TEST_UNSPEC]     = { .type = NLA_REJECT },
> >       [IFLA_BRIDGE_MRP_START_TEST_RING_ID]    = { .type = NLA_U32 },
> > -     [IFLA_BRIDGE_MRP_START_TEST_INTERVAL]   = { .type = NLA_U32 },
> > +     [IFLA_BRIDGE_MRP_START_TEST_INTERVAL]   = NLA_POLICY_MIN(NLA_U32, 1),
> >       [IFLA_BRIDGE_MRP_START_TEST_MAX_MISS]   = { .type = NLA_U32 },
> >       [IFLA_BRIDGE_MRP_START_TEST_PERIOD]     = { .type = NLA_U32 },
> >       [IFLA_BRIDGE_MRP_START_TEST_MONITOR]    = { .type = NLA_U32 },
> > @@ -316,7 +316,7 @@ static const struct nla_policy
> >   br_mrp_start_in_test_policy[IFLA_BRIDGE_MRP_START_IN_TEST_MAX + 1] = {
> >       [IFLA_BRIDGE_MRP_START_IN_TEST_UNSPEC]  = { .type = NLA_REJECT },
> >       [IFLA_BRIDGE_MRP_START_IN_TEST_IN_ID]   = { .type = NLA_U32 },
> > -     [IFLA_BRIDGE_MRP_START_IN_TEST_INTERVAL]        = { .type = NLA_U32 },
> > +     [IFLA_BRIDGE_MRP_START_IN_TEST_INTERVAL]        = NLA_POLICY_MIN(NLA_U32, 1),
> >       [IFLA_BRIDGE_MRP_START_IN_TEST_MAX_MISS]        = { .type = NLA_U32 },
> >       [IFLA_BRIDGE_MRP_START_IN_TEST_PERIOD]  = { .type = NLA_U32 },
> >   };
>
> Alright, let's limit them :-)
>
> Acked-by: Nikolay Aleksandrov <razor@blackwall.org>
>

Re: [PATCH net v2] bridge: mrp: reject zero test interval to avoid OOM panic

[Ido Schimmel]

On Fri, Mar 27, 2026 at 11:30:00PM -0700, Xiang Mei wrote:
> br_mrp_start_test() and br_mrp_start_in_test() accept the user-supplied
> interval value from netlink without validation. When interval is 0,
> usecs_to_jiffies(0) yields 0, causing the delayed work
> (br_mrp_test_work_expired / br_mrp_in_test_work_expired) to reschedule
> itself with zero delay. This creates a tight loop on system_percpu_wq
> that allocates and transmits MRP test frames at maximum rate, exhausting
> all system memory and causing a kernel panic via OOM deadlock.
> 
> The same zero-interval issue applies to br_mrp_start_in_test_parse()
> for interconnect test frames.
> 
> Use NLA_POLICY_MIN(NLA_U32, 1) in the nla_policy tables for both
> IFLA_BRIDGE_MRP_START_TEST_INTERVAL and
> IFLA_BRIDGE_MRP_START_IN_TEST_INTERVAL, so zero is rejected at the
> netlink attribute parsing layer before the value ever reaches the
> workqueue scheduling code. This is consistent with how other bridge
> subsystems (br_fdb, br_mst) enforce range constraints on netlink
> attributes.
> 
> Fixes: 20f6a05ef635 ("bridge: mrp: Rework the MRP netlink interface")
> Fixes: 7ab1748e4ce6 ("bridge: mrp: Extend MRP netlink interface for configuring MRP interconnect")
> Reported-by: Weiming Shi <bestswngs@gmail.com>
> Signed-off-by: Xiang Mei <xmei5@asu.edu>

Reviewed-by: Ido Schimmel <idosch@nvidia.com>

Re: [PATCH net v2] bridge: mrp: reject zero test interval to avoid OOM panic

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by Paolo Abeni <pabeni@redhat.com>:

On Fri, 27 Mar 2026 23:30:00 -0700 you wrote:
> br_mrp_start_test() and br_mrp_start_in_test() accept the user-supplied
> interval value from netlink without validation. When interval is 0,
> usecs_to_jiffies(0) yields 0, causing the delayed work
> (br_mrp_test_work_expired / br_mrp_in_test_work_expired) to reschedule
> itself with zero delay. This creates a tight loop on system_percpu_wq
> that allocates and transmits MRP test frames at maximum rate, exhausting
> all system memory and causing a kernel panic via OOM deadlock.
> 
> [...]

Here is the summary with links:
  - [net,v2] bridge: mrp: reject zero test interval to avoid OOM panic
    https://git.kernel.org/netdev/net/c/fa6e24963342

You are awesome, thank you!
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