[PATCH net 4/6] net/ncsi: validate OEM response payloads before parsing

[Michael Bommarito <michael.bommarito@gmail.com>]

Reject truncated OEM responses before reading the manufacturer ID,
vendor-specific subheaders, or vendor MAC address payloads.

The OEM response dispatcher reads rsp->mfr_id without verifying that the
skb contains the manufacturer field and checksum. The Mellanox,
Broadcom, and Intel handlers then read their command-specific headers
without checking that the payload is large enough for those fields. The
shared GMA helper finally copies a MAC address from a
manufacturer-specific offset without validating that the payload reaches
that offset.

Validate the advertised payload before each of those reads so malformed
or truncated BMC responses are rejected before the parser touches data
past the end of the skb.

Fixes: fb4ee67529ff ("net/ncsi: Add NCSI OEM command support")
Fixes: cb10c7c0dfd9 ("net/ncsi: Add NCSI Broadcom OEM command")
Fixes: 16e8c4ca21a2 ("net/ncsi: Add NCSI Mellanox OEM command")
Fixes: 205b95fe658d ("net/ncsi: add get MAC address command to get Intel i210 MAC address")
Cc: stable@vger.kernel.org
Assisted-by: Claude:claude-opus-4-7
Signed-off-by: Michael Bommarito <michael.bommarito@gmail.com>
---
 net/ncsi/ncsi-rsp.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/net/ncsi/ncsi-rsp.c b/net/ncsi/ncsi-rsp.c
index cbddb2012f90..94354dca23ea 100644
--- a/net/ncsi/ncsi-rsp.c
+++ b/net/ncsi/ncsi-rsp.c
@@ -656,6 +656,7 @@ static int ncsi_rsp_handler_oem_gma(struct ncsi_request *nr, int mfr_id)
 	struct net_device *ndev = ndp->ndev.dev;
 	struct ncsi_rsp_oem_pkt *rsp;
 	u32 mac_addr_off = 0;
+	unsigned int payload;
 
 	/* Get the response header */
 	rsp = (struct ncsi_rsp_oem_pkt *)skb_network_header(nr->rsp);
@@ -668,6 +669,11 @@ static int ncsi_rsp_handler_oem_gma(struct ncsi_request *nr, int mfr_id)
 	else if (mfr_id == NCSI_OEM_MFR_INTEL_ID)
 		mac_addr_off = INTEL_MAC_ADDR_OFFSET;
 
+	payload = ncsi_rsp_payload(nr->rsp);
+	if (payload < sizeof(rsp->mfr_id) + mac_addr_off + ETH_ALEN +
+		      sizeof(__be32))
+		return -EINVAL;
+
 	saddr->ss_family = ndev->type;
 	memcpy(saddr->__data, &rsp->data[mac_addr_off], ETH_ALEN);
 	if (mfr_id == NCSI_OEM_MFR_BCM_ID || mfr_id == NCSI_OEM_MFR_INTEL_ID)
@@ -686,9 +692,14 @@ static int ncsi_rsp_handler_oem_mlx(struct ncsi_request *nr)
 {
 	struct ncsi_rsp_oem_mlx_pkt *mlx;
 	struct ncsi_rsp_oem_pkt *rsp;
+	unsigned int payload;
 
 	/* Get the response header */
 	rsp = (struct ncsi_rsp_oem_pkt *)skb_network_header(nr->rsp);
+	payload = ncsi_rsp_payload(nr->rsp);
+	if (payload < sizeof(rsp->mfr_id) + sizeof(*mlx) + sizeof(__be32))
+		return -EINVAL;
+
 	mlx = (struct ncsi_rsp_oem_mlx_pkt *)(rsp->data);
 
 	if (mlx->cmd == NCSI_OEM_MLX_CMD_GMA &&
@@ -702,9 +713,14 @@ static int ncsi_rsp_handler_oem_bcm(struct ncsi_request *nr)
 {
 	struct ncsi_rsp_oem_bcm_pkt *bcm;
 	struct ncsi_rsp_oem_pkt *rsp;
+	unsigned int payload;
 
 	/* Get the response header */
 	rsp = (struct ncsi_rsp_oem_pkt *)skb_network_header(nr->rsp);
+	payload = ncsi_rsp_payload(nr->rsp);
+	if (payload < sizeof(rsp->mfr_id) + sizeof(*bcm) + sizeof(__be32))
+		return -EINVAL;
+
 	bcm = (struct ncsi_rsp_oem_bcm_pkt *)(rsp->data);
 
 	if (bcm->type == NCSI_OEM_BCM_CMD_GMA)
@@ -717,9 +733,14 @@ static int ncsi_rsp_handler_oem_intel(struct ncsi_request *nr)
 {
 	struct ncsi_rsp_oem_intel_pkt *intel;
 	struct ncsi_rsp_oem_pkt *rsp;
+	unsigned int payload;
 
 	/* Get the response header */
 	rsp = (struct ncsi_rsp_oem_pkt *)skb_network_header(nr->rsp);
+	payload = ncsi_rsp_payload(nr->rsp);
+	if (payload < sizeof(rsp->mfr_id) + sizeof(*intel) + sizeof(__be32))
+		return -EINVAL;
+
 	intel = (struct ncsi_rsp_oem_intel_pkt *)(rsp->data);
 
 	if (intel->cmd == NCSI_OEM_INTEL_CMD_GMA)
@@ -742,10 +763,15 @@ static int ncsi_rsp_handler_oem(struct ncsi_request *nr)
 {
 	struct ncsi_rsp_oem_handler *nrh = NULL;
 	struct ncsi_rsp_oem_pkt *rsp;
+	unsigned int payload;
 	unsigned int mfr_id, i;
 
 	/* Get the response header */
 	rsp = (struct ncsi_rsp_oem_pkt *)skb_network_header(nr->rsp);
+	payload = ncsi_rsp_payload(nr->rsp);
+	if (payload < sizeof(rsp->mfr_id) + sizeof(__be32))
+		return -EINVAL;
+
 	mfr_id = ntohl(rsp->mfr_id);
 
 	/* Check for manufacturer id and Find the handler */
-- 
2.53.0