linux-kernel - Re: [PATCH] media: amphion: fix potential NULL deref in vpu_core_parse

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Message-ID: <77ed36f63ec02156d480efebafb80f3af3ea50f0.camel@ndufresne.ca>
Date: Fri, 11 Apr 2025 17:20:23 -0400
From: Nicolas Dufresne <nicolas@...fresne.ca>
To: Chenyuan Yang <chenyuan0y@...il.com>, ming.qian@....com,
 eagle.zhou@....com, 	mchehab@...nel.org, shijie.qin@....com,
 hverkuil@...all.nl
Cc: linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] media: amphion: fix potential NULL deref in
 vpu_core_parse_dt()

Hi,

Le vendredi 11 avril 2025 à 13:43 -0500, Chenyuan Yang a écrit :
> The result of memremap() may be NULL on failure, leading to a null
> dereference in the subsequent memset(). Add explicit checks after
> each memremap() call: if the firmware region fails to map, return
> immediately; if the RPC region fails, unmap the firmware window before
> returning.

Its hard to believe that its a coincidence that someone else sent a
patch for this. A colleague, the same person ?

I do prefer this version though, the commits message is better, the
code is nicer. If its you, adding a [PATCH v2], or just adding a
comment that its a better version would be nice.

> 
> This is similar to the commit 966d47e1f27c
> ("efi: fix potential NULL deref in efi_mem_reserve_persistent").
> 
> This is found by our static analysis tool KNighter.
> 
> Signed-off-by: Chenyuan Yang <chenyuan0y@...il.com>
> Fixes: 9f599f351e86 ("media: amphion: add vpu core driver")
> ---
>  drivers/media/platform/amphion/vpu_core.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/drivers/media/platform/amphion/vpu_core.c b/drivers/media/platform/amphion/vpu_core.c
> index 8df85c14ab3f..26568987586d 100644
> --- a/drivers/media/platform/amphion/vpu_core.c
> +++ b/drivers/media/platform/amphion/vpu_core.c
> @@ -586,7 +586,18 @@ static int vpu_core_parse_dt(struct vpu_core *core, struct device_node *np)
>  	}
>  
>  	core->fw.virt = memremap(core->fw.phys, core->fw.length, MEMREMAP_WC);
> +	if (!core->fw.virt) {
> +		dev_err(core->dev, "failed to remap fw region\n");
> +		of_node_put(node);

nit: node and res are no longer used passed line 579. Meaning you could
unref the node earlier, and remove the repeated of_node_put(node) call
in the error conditions.

> +		return -ENOMEM;
> +	}
>  	core->rpc.virt = memremap(core->rpc.phys, core->rpc.length, MEMREMAP_WC);

I really enjoy blank lines after closing scope, even though its not a
strict coding standard.

> +	if (!core->rpc.virt) {
> +		dev_err(core->dev, "failed to remap rpc region\n");
> +		memunmap(core->fw.virt);

Its interesting that you thought of cleaning that up here, since its
not being cleanup in the error case of "if (ret !=
VPU_CORE_MEMORY_UNCACHED)".  And its also not being cleanup if the
probe fails later for other reasons. Perhaps your chance to add more
fixes to this driver.

> +		of_node_put(node);
> +		return -ENOMEM;
> +	}
>  	memset(core->rpc.virt, 0, core->rpc.length);

Same, I like blank lines (but you are free to ignore me if Ming does
not care).

>  
>  	ret = vpu_iface_check_memory_region(core, core->rpc.phys, core->rpc.length);

regards,
Nicolas