[PATCH 01/17] i3c: renesas: Check that the transfer is valid before accessing it

[Claudiu Beznea <claudiu.beznea@kernel.org>]

From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>

The Renesas I3C driver uses an asynchronous model to transfer data. It
prepares a struct renesas_i3c_xfer, enqueues it, and waits for completion.
The interrupt handler dequeues the transfer, updates/uses it, and signals
the waiting thread.

If the completion times out, the waiting thread dequeues the transfer and
free it. If an interrupt fires after that, the handler may access freed
memory, leading to crashes.

Check that the transfer is still valid before accessing it in the
interrupt handler.

Fixes: d028219a9f14 ("i3c: master: Add basic driver for the Renesas I3C controller")
Cc: stable@vger.kernel.org
Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
---
 drivers/i3c/master/renesas-i3c.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/drivers/i3c/master/renesas-i3c.c b/drivers/i3c/master/renesas-i3c.c
index f39c449922ca..36e3ccbe66b0 100644
--- a/drivers/i3c/master/renesas-i3c.c
+++ b/drivers/i3c/master/renesas-i3c.c
@@ -1014,6 +1014,9 @@ static irqreturn_t renesas_i3c_tx_isr(int irq, void *data)
 
 	scoped_guard(spinlock, &i3c->xferqueue.lock) {
 		xfer = i3c->xferqueue.cur;
+		if (!xfer)
+			return IRQ_HANDLED;
+
 		cmd = xfer->cmds;
 
 		if (xfer->is_i2c_xfer) {
@@ -1054,6 +1057,9 @@ static irqreturn_t renesas_i3c_resp_isr(int irq, void *data)
 
 	scoped_guard(spinlock, &i3c->xferqueue.lock) {
 		xfer = i3c->xferqueue.cur;
+		if (!xfer)
+			return IRQ_HANDLED;
+
 		cmd = xfer->cmds;
 
 		/* Clear the Respone Queue Full status flag*/
@@ -1138,6 +1144,9 @@ static irqreturn_t renesas_i3c_tend_isr(int irq, void *data)
 
 	scoped_guard(spinlock, &i3c->xferqueue.lock) {
 		xfer = i3c->xferqueue.cur;
+		if (!xfer)
+			return IRQ_HANDLED;
+
 		cmd = xfer->cmds;
 
 		if (xfer->is_i2c_xfer) {
@@ -1184,6 +1193,9 @@ static irqreturn_t renesas_i3c_rx_isr(int irq, void *data)
 
 	scoped_guard(spinlock, &i3c->xferqueue.lock) {
 		xfer = i3c->xferqueue.cur;
+		if (!xfer)
+			return IRQ_HANDLED;
+
 		cmd = xfer->cmds;
 
 		if (xfer->is_i2c_xfer) {
@@ -1235,6 +1247,8 @@ static irqreturn_t renesas_i3c_stop_isr(int irq, void *data)
 
 	scoped_guard(spinlock, &i3c->xferqueue.lock) {
 		xfer = i3c->xferqueue.cur;
+		if (!xfer)
+			return IRQ_HANDLED;
 
 		/* read back registers to confirm writes have fully propagated */
 		renesas_writel(i3c->regs, BST, 0);
@@ -1259,6 +1273,9 @@ static irqreturn_t renesas_i3c_start_isr(int irq, void *data)
 
 	scoped_guard(spinlock, &i3c->xferqueue.lock) {
 		xfer = i3c->xferqueue.cur;
+		if (!xfer)
+			return IRQ_HANDLED;
+
 		cmd = xfer->cmds;
 
 		if (xfer->is_i2c_xfer) {
-- 
2.43.0