linux-kernel - Re: [PATCH v2] staging: pi433: add mutex fixing concurrency issues.

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Message-ID: <20180613005807.GB2265@hle-laptop.local>
Date:   Tue, 12 Jun 2018 20:58:07 -0400
From:   Hugo Lefeuvre <hle@....eu.com>
To:     Dan Carpenter <dan.carpenter@...cle.com>
Cc:     devel@...verdev.osuosl.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        kernelnewbies@...nelnewbies.org, linux-kernel@...r.kernel.org,
        Valentin Vidic <Valentin.Vidic@...Net.hr>
Subject: Re: [PATCH v2] staging: pi433: add mutex fixing concurrency issues.

> > case PI433_IOC_WR_TX_CFG:
> >         if (copy_from_user(&instance->tx_cfg, argp,
> >                    sizeof(struct pi433_tx_cfg)))
> >             return -EFAULT;
> >         break;
> 
> Btw, it looks so wrong to me that we copy partial data to
> &instance->tx_cfg...  I'd really prefer copying it to a tmp buffer and
> then verifying it's corrent then memcpy()ing it to &instance->tx_cfg.

AFAIK this piece of code is not supposed to check passed tx config.
These checks are realised later by rf69_set_tx_cfg (called by
pi433_tx_thread) after the config has been written to the fifo by
pi433_write.

What kind of checks do you want to perform exactly ?

But, right, I prefer the idea of the temporary buffer too, and seeing the
rest of kernel code it seems to be the usual way to go.

Regards,
 Hugo

-- 
             Hugo Lefeuvre (hle)    |    www.owl.eu.com
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