Re: [PATCH] mailbox: bcm74110: Cap rx_svc_init_list growth to prevent PMC-induced OOM

[Justin Chen <justin.chen@broadcom.com>]

On 8/25/26 12:16 PM, Danesh Petigara wrote:
> From: Florian Fainelli <florian.fainelli@broadcom.com>
> 
> bcm74110_rx_push_init_msg() allocates a GFP_ATOMIC struct for every
> BCM_MSG_SVC_INIT word received from the PMC co-processor and appends it
> to rx_svc_init_list with no cap on list length.  The only consumers of
> this list (bcm74110_rx_pop_init_msg_block / bcm74110_rx_flush_msg) are
> called only during probe and at shutdown respectively; after probe
> completes, PMC firmware can continuously inject BCM_MSG_SVC_INIT words,
> exhausting GFP_ATOMIC reserves and causing a whole-device denial of
> service.
> 
> Add BCM74110_INIT_MSG_MAX (16 entries) as the maximum list depth.
> bcm74110_rx_push_init_msg() now checks the count under the existing
> rx_svc_list_lock before allocating; if the cap is reached the message is
> dropped and a rate-limited warning is emitted.  The new rx_svc_init_count
> field is decremented by bcm74110_rx_pop_init_msg() on successful dequeue
> and reset to zero by bcm74110_rx_flush_msg() on shutdown.
> 
> Fixes: 52436007b862 ("mailbox: Add support for bcm74110")
> Cc: stable@vger.kernel.org
> Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>
> Assisted-by: Anthropic:claude-sonnet-4.6 cursor
> Signed-off-by: Danesh Petigara <danesh.petigara@broadcom.com>

Signed-off-by: Justin Chen <justin.chen@broadcom.com>

Gentle ping on this patch.

Thanks,
Justin