net: ti: icss-iep: Fix possible NULL pointer dereference for perout request

The ICSS IEP driver tracks perout and pps enable state with flags.
Currently when disabling pps and perout signals during icss_iep_exit(),
results in NULL pointer dereference for perout.

To fix the null pointer dereference issue, the icss_iep_perout_enable_hw
function can be modified to directly clear the IEP CMP registers when
disabling PPS or PEROUT, without referencing the ptp_perout_request
structure, as its contents are irrelevant in this case.

Fixes: 9b11536 ("net: ti: icssg-prueth: Fix clearing of IEP_CMP_CFG registers during iep_init")
Reported-by: Dan Carpenter <[email protected]>
Closes: https://lore.kernel.org/all/[email protected]/
Signed-off-by: Meghana Malladi <[email protected]>
Reviewed-by: Jacob Keller <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Paolo Abeni <[email protected]>

Author: MeghanaMalladiTI

drivers/net/ethernet/ti/icssg/icss_iep.c

@@ -412,6 +412,22 @@ static int icss_iep_perout_enable_hw(struct icss_iep *iep,
 	int ret;
 	u64 cmp;
 
+	if (!on) {
+		/* Disable CMP 1 */
+		regmap_update_bits(iep->map, ICSS_IEP_CMP_CFG_REG,
+				   IEP_CMP_CFG_CMP_EN(1), 0);
+
+		/* clear CMP regs */
+		regmap_write(iep->map, ICSS_IEP_CMP1_REG0, 0);
+		if (iep->plat_data->flags & ICSS_IEP_64BIT_COUNTER_SUPPORT)
+			regmap_write(iep->map, ICSS_IEP_CMP1_REG1, 0);
+
+		/* Disable sync */
+		regmap_write(iep->map, ICSS_IEP_SYNC_CTRL_REG, 0);
+
+		return 0;
+	}
+
 	/* Calculate width of the signal for PPS/PEROUT handling */
 	ts.tv_sec = req->on.sec;
 	ts.tv_nsec = req->on.nsec;
@@ -430,64 +446,39 @@ static int icss_iep_perout_enable_hw(struct icss_iep *iep,
 		if (ret)
 			return ret;
 
-		if (on) {
-			/* Configure CMP */
-			regmap_write(iep->map, ICSS_IEP_CMP1_REG0, lower_32_bits(cmp));
-			if (iep->plat_data->flags & ICSS_IEP_64BIT_COUNTER_SUPPORT)
-				regmap_write(iep->map, ICSS_IEP_CMP1_REG1, upper_32_bits(cmp));
-			/* Configure SYNC, based on req on width */
-			regmap_write(iep->map, ICSS_IEP_SYNC_PWIDTH_REG,
-				     div_u64(ns_width, iep->def_inc));
-			regmap_write(iep->map, ICSS_IEP_SYNC0_PERIOD_REG, 0);
-			regmap_write(iep->map, ICSS_IEP_SYNC_START_REG,
-				     div_u64(ns_start, iep->def_inc));
-			regmap_write(iep->map, ICSS_IEP_SYNC_CTRL_REG, 0); /* one-shot mode */
-			/* Enable CMP 1 */
-			regmap_update_bits(iep->map, ICSS_IEP_CMP_CFG_REG,
-					   IEP_CMP_CFG_CMP_EN(1), IEP_CMP_CFG_CMP_EN(1));
-		} else {
-			/* Disable CMP 1 */
-			regmap_update_bits(iep->map, ICSS_IEP_CMP_CFG_REG,
-					   IEP_CMP_CFG_CMP_EN(1), 0);
-
-			/* clear regs */
-			regmap_write(iep->map, ICSS_IEP_CMP1_REG0, 0);
-			if (iep->plat_data->flags & ICSS_IEP_64BIT_COUNTER_SUPPORT)
-				regmap_write(iep->map, ICSS_IEP_CMP1_REG1, 0);
-		}
+		/* Configure CMP */
+		regmap_write(iep->map, ICSS_IEP_CMP1_REG0, lower_32_bits(cmp));
+		if (iep->plat_data->flags & ICSS_IEP_64BIT_COUNTER_SUPPORT)
+			regmap_write(iep->map, ICSS_IEP_CMP1_REG1, upper_32_bits(cmp));
+		/* Configure SYNC, based on req on width */
+		regmap_write(iep->map, ICSS_IEP_SYNC_PWIDTH_REG,
+			     div_u64(ns_width, iep->def_inc));
+		regmap_write(iep->map, ICSS_IEP_SYNC0_PERIOD_REG, 0);
+		regmap_write(iep->map, ICSS_IEP_SYNC_START_REG,
+			     div_u64(ns_start, iep->def_inc));
+		regmap_write(iep->map, ICSS_IEP_SYNC_CTRL_REG, 0); /* one-shot mode */
+		/* Enable CMP 1 */
+		regmap_update_bits(iep->map, ICSS_IEP_CMP_CFG_REG,
+				   IEP_CMP_CFG_CMP_EN(1), IEP_CMP_CFG_CMP_EN(1));
 	} else {
-		if (on) {
-			u64 start_ns;
-
-			iep->period = ((u64)req->period.sec * NSEC_PER_SEC) +
-				      req->period.nsec;
-			start_ns = ((u64)req->period.sec * NSEC_PER_SEC)
-				   + req->period.nsec;
-			icss_iep_update_to_next_boundary(iep, start_ns);
-
-			regmap_write(iep->map, ICSS_IEP_SYNC_PWIDTH_REG,
-				     div_u64(ns_width, iep->def_inc));
-			regmap_write(iep->map, ICSS_IEP_SYNC_START_REG,
-				     div_u64(ns_start, iep->def_inc));
-			/* Enable Sync in single shot mode  */
-			regmap_write(iep->map, ICSS_IEP_SYNC_CTRL_REG,
-				     IEP_SYNC_CTRL_SYNC_N_EN(0) | IEP_SYNC_CTRL_SYNC_EN);
-			/* Enable CMP 1 */
-			regmap_update_bits(iep->map, ICSS_IEP_CMP_CFG_REG,
-					   IEP_CMP_CFG_CMP_EN(1), IEP_CMP_CFG_CMP_EN(1));
-		} else {
-			/* Disable CMP 1 */
-			regmap_update_bits(iep->map, ICSS_IEP_CMP_CFG_REG,
-					   IEP_CMP_CFG_CMP_EN(1), 0);
-
-			/* clear CMP regs */
-			regmap_write(iep->map, ICSS_IEP_CMP1_REG0, 0);
-			if (iep->plat_data->flags & ICSS_IEP_64BIT_COUNTER_SUPPORT)
-				regmap_write(iep->map, ICSS_IEP_CMP1_REG1, 0);
-
-			/* Disable sync */
-			regmap_write(iep->map, ICSS_IEP_SYNC_CTRL_REG, 0);
-		}
+		u64 start_ns;
+
+		iep->period = ((u64)req->period.sec * NSEC_PER_SEC) +
+				req->period.nsec;
+		start_ns = ((u64)req->period.sec * NSEC_PER_SEC)
+				+ req->period.nsec;
+		icss_iep_update_to_next_boundary(iep, start_ns);
+
+		regmap_write(iep->map, ICSS_IEP_SYNC_PWIDTH_REG,
+			     div_u64(ns_width, iep->def_inc));
+		regmap_write(iep->map, ICSS_IEP_SYNC_START_REG,
+			     div_u64(ns_start, iep->def_inc));
+		/* Enable Sync in single shot mode  */
+		regmap_write(iep->map, ICSS_IEP_SYNC_CTRL_REG,
+			     IEP_SYNC_CTRL_SYNC_N_EN(0) | IEP_SYNC_CTRL_SYNC_EN);
+		/* Enable CMP 1 */
+		regmap_update_bits(iep->map, ICSS_IEP_CMP_CFG_REG,
+				   IEP_CMP_CFG_CMP_EN(1), IEP_CMP_CFG_CMP_EN(1));
 	}
 
 	return 0;
@@ -498,11 +489,21 @@ static int icss_iep_perout_enable(struct icss_iep *iep,
 {
 	int ret = 0;
 
+	if (!on)
+		goto disable;
+
 	/* Reject requests with unsupported flags */
 	if (req->flags & ~(PTP_PEROUT_DUTY_CYCLE |
 			  PTP_PEROUT_PHASE))
 		return -EOPNOTSUPP;
 
+	/* Set default "on" time (1ms) for the signal if not passed by the app */
+	if (!(req->flags & PTP_PEROUT_DUTY_CYCLE)) {
+		req->on.sec = 0;
+		req->on.nsec = NSEC_PER_MSEC;
+	}
+
+disable:
 	mutex_lock(&iep->ptp_clk_mutex);
 
 	if (iep->pps_enabled) {
@@ -513,12 +514,6 @@ static int icss_iep_perout_enable(struct icss_iep *iep,
 	if (iep->perout_enabled == !!on)
 		goto exit;
 
-	/* Set default "on" time (1ms) for the signal if not passed by the app */
-	if (!(req->flags & PTP_PEROUT_DUTY_CYCLE)) {
-		req->on.sec = 0;
-		req->on.nsec = NSEC_PER_MSEC;
-	}
-
 	ret = icss_iep_perout_enable_hw(iep, req, on);
 	if (!ret)
 		iep->perout_enabled = !!on;