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

[Frank Li]

On Fri, May 22, 2026 at 01:17:59PM +0300, Claudiu Beznea wrote:
> From: Claudiu Beznea <claudiu.beznea.uj@xxxxxxxxxxxxxx>
>
> 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@xxxxxxxxxxxxxxx
> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@xxxxxxxxxxxxxx>
> ---

Reviewed-by: Frank Li <Frank.Li@xxxxxxx>

>  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
>