Re: [PATCH] i3c: fix potential NULL dereference in send_ccc_cmd_locked

[Mukesh Savaliya]

On 7/28/2026 12:00 PM, Hongling Zeng wrote:
> The retry loop added in commit 02cc832191dd ("i3c: master: Validate GET
>   CCC payload length and retry Direct GET once") resets payload actual_len
> before each attempt. However, cmd->dests is only validated for DIRECT
> CCC commands (I3C_CCC_DIRECT bit set). For broadcast commands, dests
> can be NULL while ndests > 0, causing a NULL pointer dereference at
> cmd->dests[i].payload.actual_len.
>
> Fix by restricting the actual_len reset to DIRECT commands.
>
> Fixes: 02cc832191dd ("i3c: master: Validate GET CCC payload length and retry Direct GET once")
> Signed-off-by: Hongling Zeng <zenghongling@xxxxxxxxxx>
> ---
>   drivers/i3c/master.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c
> index fd3e79d10c84..21212c34c31e 100644
> --- a/drivers/i3c/master.c
> +++ b/drivers/i3c/master.c
> @@ -1051,7 +1051,7 @@ static int i3c_master_send_ccc_cmd_locked(struct i3c_master_controller *master,
>   	for (attempt = 0; attempt < max_attempts; attempt++) {
>   		unsigned int i;
>   
> -		if (cmd->rnw)
> +		if (cmd->rnw && (cmd->id & I3C_CCC_DIRECT))

Please review this recent fix @
https://lore.kernel.org/all/amJau9LgehYLnR20@lizhi-Precision-Tower-5810/

>   			for (i = 0; i < cmd->ndests; i++)
>   				cmd->dests[i].payload.actual_len = 0;
>