[PATCH-next] mailbox: th1520: Fix out of bounds write

[PATCH-next] mailbox: th1520: Fix out of bounds write

[Advait Dhamorikar]

The loop in the function iterates up to `TH_1520_MBOX_CHANS`,
but the `ctx->intr_mask` array only has 3 elements. When 
`TH_1520_MBOX_CHANS` is set to a value larger than 3, this
causes an out-of-bounds write at `ctx->intr_mask[3]`.
This could cause an immediate crash or incorrect computations.

Signed-off-by: Advait Dhamorikar <advaitdhamorikar@gmail.com>
---
 drivers/mailbox/mailbox-th1520.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/mailbox/mailbox-th1520.c b/drivers/mailbox/mailbox-th1520.c
index 4e84640ac3b8..759634a4fb72 100644
--- a/drivers/mailbox/mailbox-th1520.c
+++ b/drivers/mailbox/mailbox-th1520.c
@@ -532,6 +532,9 @@ static int __maybe_unused th1520_mbox_suspend_noirq(struct device *dev)
 	 * INFO data all assumed to be lost.
 	 */
 	for (i = 0; i < TH_1520_MBOX_CHANS; i++) {
+		if (i >= ARRAY_SIZE(ctx->intr_mask))
+			break;
+
 		ctx->intr_mask[i] =
 			ioread32(priv->local_icu[i] + TH_1520_MBOX_MASK);
 	}
-- 
2.34.1

Re: [PATCH-next] mailbox: th1520: Fix out of bounds write

[Jassi Brar]

On Mon, Nov 25, 2024 at 1:10 PM Advait Dhamorikar
<advaitdhamorikar@gmail.com> wrote:
>
> The loop in the function iterates up to `TH_1520_MBOX_CHANS`,
> but the `ctx->intr_mask` array only has 3 elements. When
> `TH_1520_MBOX_CHANS` is set to a value larger than 3, this
> causes an out-of-bounds write at `ctx->intr_mask[3]`.
> This could cause an immediate crash or incorrect computations.
>
> Signed-off-by: Advait Dhamorikar <advaitdhamorikar@gmail.com>
> ---
>  drivers/mailbox/mailbox-th1520.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/drivers/mailbox/mailbox-th1520.c b/drivers/mailbox/mailbox-th1520.c
> index 4e84640ac3b8..759634a4fb72 100644
> --- a/drivers/mailbox/mailbox-th1520.c
> +++ b/drivers/mailbox/mailbox-th1520.c
> @@ -532,6 +532,9 @@ static int __maybe_unused th1520_mbox_suspend_noirq(struct device *dev)
>          * INFO data all assumed to be lost.
>          */
>         for (i = 0; i < TH_1520_MBOX_CHANS; i++) {
> +               if (i >= ARRAY_SIZE(ctx->intr_mask))
> +                       break;
> +
Maybe simply reduce the loop by one OR iterate for
ARRAY_SIZE(ctx->intr_mask), here and elsewhere?
I have a gut feeling that intr_mask is declared one element short.
CC'ing the author.

Thanks