RE: [EXTERNAL] [PATCH net] octeontx2-af: validate MCS blocks before initialization

[Geethasowjanya Akula]

>-----Original Message-----
>From: Slavin Liu <bolin.liu@xxxxxxxxxx>
>Sent: Sunday, September 13, 2026 6:22 PM
>To: Sunil Kovvuri Goutham <sgoutham@xxxxxxxxxxx>; Ratheesh Kannoth
><rkannoth@xxxxxxxxxxx>; Geethasowjanya Akula <gakula@xxxxxxxxxxx>;
>Subbaraya Sundeep Bhatta <sbhatta@xxxxxxxxxxx>;
>andrew+netdev@xxxxxxx; davem@xxxxxxxxxxxxx; edumazet@xxxxxxxxxx;
>kuba@xxxxxxxxxx; pabeni@xxxxxxxxxx
>Cc: netdev@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
>bolin.liu@xxxxxxxxxx
>Subject: [EXTERNAL] [PATCH net] octeontx2-af: validate MCS blocks before
>initialization
>The MCS count is a maximum successful ID plus one, not proof of a dense
>device set. Validate the complete range before programming any block, so a
>failed lower-ID probe cannot cause a NULL dereference.
>
>Detected by static analysis and reviewed with AI-assisted source auditing.
>
>Fixes: 080bbd19c9dd ("octeontx2-af: cn10k: mcs: Add mailboxes for port
>related operations")
>Assisted-by: LLM
>Signed-off-by: Slavin Liu <bolin.liu@xxxxxxxxxx>
>---
> drivers/net/ethernet/marvell/octeontx2/af/mcs_rvu_if.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
>diff --git a/drivers/net/ethernet/marvell/octeontx2/af/mcs_rvu_if.c
>b/drivers/net/ethernet/marvell/octeontx2/af/mcs_rvu_if.c
>index fce22e314cac..0ee2d0d698e5 100644
>--- a/drivers/net/ethernet/marvell/octeontx2/af/mcs_rvu_if.c
>+++ b/drivers/net/ethernet/marvell/octeontx2/af/mcs_rvu_if.c
>@@ -889,6 +889,11 @@ int rvu_mcs_init(struct rvu *rvu)
> 		rvu_mcs_set_lmac_bmap(rvu);
> 	}
>
>+	for (mcs_id = 0; mcs_id < rvu->mcs_blk_cnt; mcs_id++) {
>+		if (!mcs_get_pdata(mcs_id))
>+			return -ENODEV;
>+	}
>+
> 	/* Install default tcam bypass entry and set port to operational mode
>*/
> 	for (mcs_id = 0; mcs_id < rvu->mcs_blk_cnt; mcs_id++) {
> 		mcs = mcs_get_pdata(mcs_id);

Thanks, Slavin, for the patch.
The additional check can be moved into the existing loop below, which avoids iterating over the MCS blocks twice.

Also, on CN10KB silicon, the MCS block count is always 1. Therefore, the existing check: "if (!rvu->mcs_blk_cnt)" 
should be sufficient to handle the absence of MCS blocks.
          
@@ -892,6 +892,8 @@ int rvu_mcs_init(struct rvu *rvu)
        /* Install default tcam bypass entry and set port to operational mode */
        for (mcs_id = 0; mcs_id < rvu->mcs_blk_cnt; mcs_id++) {
                mcs = mcs_get_pdata(mcs_id);
+               if (!mcs_get_pdata(mcs_id))
+                       return -ENODEV
                mcs_install_flowid_bypass_entry(mcs);