[PATCH net] dpaa2-switch: validate num_ifs to prevent out-of-bounds write

[Junrui Luo]

The driver obtains sw_attr.num_ifs from firmware via dpsw_get_attributes()
but never validates it against DPSW_MAX_IF (64). This value controls
iteration in dpaa2_switch_fdb_get_flood_cfg(), which writes port indices
into the fixed-size cfg->if_id[DPSW_MAX_IF] array. When firmware reports
num_ifs >= 64, the loop can write past the array bounds.

Add a bound check for num_ifs in dpaa2_switch_init().

Reported-by: Yuhao Jiang <danisjiang@xxxxxxxxx>
Reported-by: Junrui Luo <moonafterrain@xxxxxxxxxxx>
Fixes: f054e3e217e4 ("dpaa2-switch: refactor the egress flooding domain setup")
Signed-off-by: Junrui Luo <moonafterrain@xxxxxxxxxxx>
---
 drivers/net/ethernet/freescale/dpaa2/dpaa2-switch.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/net/ethernet/freescale/dpaa2/dpaa2-switch.c b/drivers/net/ethernet/freescale/dpaa2/dpaa2-switch.c
index 66240c340492..78e21b46a5ba 100644
--- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-switch.c
+++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-switch.c
@@ -3034,6 +3034,13 @@ static int dpaa2_switch_init(struct fsl_mc_device *sw_dev)
 		goto err_close;
 	}
 
+	if (ethsw->sw_attr.num_ifs >= DPSW_MAX_IF) {
+		dev_err(dev, "DPSW num_ifs %u exceeds max %u\n",
+			ethsw->sw_attr.num_ifs, DPSW_MAX_IF);
+		err = -EINVAL;
+		goto err_close;
+	}
+
 	err = dpsw_get_api_version(ethsw->mc_io, 0,
 				   &ethsw->major,
 				   &ethsw->minor);

---
base-commit: 9702969978695d9a699a1f34771580cdbb153b33
change-id: 20260217-fixes-32df5449b0ab

Best regards,
-- 
Junrui Luo <moonafterrain@xxxxxxxxxxx>