Re: [PATCH v7 10/15] media: qcom: Switch to generic PAS TZ APIs

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] Unconditional call to `qcom_scm_mem_protect_video_var()` after relaxing probe deferral checks to `qcom_pas_is_available()` leads to a NULL pointer dereference on systems using non-SCM PAS backends.
--

commit c279727d5017499db9e28d15aedc68710604c9b9
Author: Sumit Garg <sumit.garg@oss.qualcomm.com>

media: qcom: Switch to generic PAS TZ APIs

This commit updates the Qualcomm media client drivers to use the generic
PAS TZ APIs instead of the SCM-specific ones. This allows supporting
multiple TrustZone implementation backends like OP-TEE in addition to the
QTEE-based SCM PAS service.

> diff --git a/drivers/media/platform/qcom/venus/firmware.c b/drivers/media/platform/qcom/venus/firmware.c
> index 1de7436713ed9..3a38ff985822f 100644
> --- a/drivers/media/platform/qcom/venus/firmware.c
> +++ b/drivers/media/platform/qcom/venus/firmware.c

[ ... ]

> @@ -218,7 +219,7 @@ int venus_boot(struct venus_core *core)
>  	int ret;
>  
>  	if (!IS_ENABLED(CONFIG_QCOM_MDT_LOADER) ||
> -	    (core->use_tz && !qcom_scm_is_available()))
> +	    (core->use_tz && !qcom_pas_is_available()))
>  		return -EPROBE_DEFER;

[Severity: High]
Can this lead to a NULL pointer dereference if SCM is not available?

By switching the availability check from qcom_scm_is_available() to
qcom_pas_is_available(), the driver can now proceed if an alternative PAS
backend (like OP-TEE) is used.

However, if content protection is configured, venus_boot() still calls
qcom_scm_mem_protect_video_var() further down in the function:

venus_boot() {
    ...
    ret = qcom_scm_mem_protect_video_var(res->cp_start,
                                         res->cp_size,
                                         res->cp_nonpixel_start,
                                         res->cp_nonpixel_size);
    ...
}

Looking at qcom_scm_mem_protect_video_var() in qcom_scm.c, it
unconditionally accesses the global __scm pointer:

qcom_scm_mem_protect_video_var() {
    ...
    ret = qcom_scm_call(__scm->dev, &desc, &res);
    ...
}

If SCM has not probed or is absent on the system, wouldn't __scm be NULL,
causing a crash when qcom_scm_mem_protect_video_var() is called? A similar
pattern also appears to exist in iris_fw_load().

>  
>  	ret = of_property_read_string_index(dev->of_node, "firmware-name", 0,

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260522115936.201208-1-sumit.garg@kernel.org?part=10