soundwire: bus: fix off-by-one when allocating slave IDs

ida_alloc_max() interprets its max argument as inclusive.

Using SDW_FW_MAX_DEVICES(16) therefore allows an ID of 16 to be
allocated, but the IRQ domain created for the bus is sized for IDs
0-15.  If 16 is returned, irq_create_mapping() fails and the driver
ends up with an invalid IRQ mapping.

Limit the allocation to 0-15 by passing SDW_FW_MAX_DEVICES - 1.

Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/r/202512240450.hlDH3nCs-lkp@intel.com/
Fixes: aab12022b076 ("soundwire: bus: Add internal slave ID and use for IRQs")
Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>
Reviewed-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Link: https://patch.msgid.link/20260110201959.2523024-1-harshit.m.mogalapalli@oracle.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

diff --git a/drivers/soundwire/bus_type.c b/drivers/soundwire/bus_type.c
index 91e70cb46fb575f3bb8d64e465e35f034904c914..5c67c13e57357dabed8c7df112f4d01eb3edda79 100644 (file)
--- a/drivers/soundwire/bus_type.c
+++ b/drivers/soundwire/bus_type.c
@@ -105,7 +105,7 @@ static int sdw_drv_probe(struct device *dev)
        if (ret)
                return ret;
 
-       ret = ida_alloc_max(&slave->bus->slave_ida, SDW_FW_MAX_DEVICES, GFP_KERNEL);
+       ret = ida_alloc_max(&slave->bus->slave_ida, SDW_FW_MAX_DEVICES - 1, GFP_KERNEL);
        if (ret < 0) {
                dev_err(dev, "Failed to allocated ID: %d\n", ret);
                return ret;