Re: [PATCH] rtw89: Fix crash by loading compressed firmware file

On Thu, 11 Nov 2021 03:28:09 +0100,
Pkshih wrote:

quoted

-----Original Message-----
From: Takashi Iwai <redacted>
Sent: Friday, November 5, 2021 11:07 PM
To: Pkshih <pkshih@realtek.com>
Cc: kvalo@codeaurora.org; linux-wireless@vger.kernel.org; Larry.Finger@gmail.com;
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] rtw89: Fix crash by loading compressed firmware file


You should put const in the cast in le32_get_bits() invocations, at
least.

For the le32_replace_bits(), ideally it should be rewritten in some
better way the compiler can catch.  e.g. use an inline function to
take a void * argument without const,

static inline void RTW89_SET_FWCMD_CXRFK_TYPE(void *cmd, unsigned int val)
{
	le32p_replace_bits((__le32 *)((u8 *)(cmd) + 2), val, GENMASK(17, 10));
}

Then the compiler will warn when you pass a const pointer there.

I have sent a patchset [1] to do these two things by patch 2 and 3.

quoted

BTW, while reading your reply, I noticed that it's an unaligned access
to a 32bit value, which is another potential breakage on some
architectures.  So the whole stuff has to be rewritten in anyway...

We use these macros/inline function on skb->data mostly, and I 
suppose skb->data is a 32bit aligned address. Since I don't have
this kind of machine on hand, I would like to defer this work until
I have one.

I actually misread the code.  The register offset is applied to __le32
pointer, so this should be fine.

quoted

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partition size we are going to download, and it is only used
by rtw89_fw_download_hdr(). So, I will set the partition size
after copying constant firmware header into skb->data.

Sounds good.

Please check if my patch works on your platform.
Thanks you.

[1] https://lore.kernel.org/linux-wireless/20211111021457.13776-1-pkshih@realtek.com/T/#t (local)

Thanks.  I'll ask people testing those patches.


Takashi