linux-kernel - Re: [PATCH v2 2/2] staging: gs

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Message-ID: <20170718015608.ehpguip72poza4ev@kerndev>
Date:   Mon, 17 Jul 2017 21:56:08 -0400
From:   Jacob von Chorus <jacobvonchorus@...hoto.ca>
To:     Joe Perches <joe@...ches.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Insop Song <insop.song@...nspeed.com>,
        devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org,
        dan.carpenter@...cle.com
Subject: Re: [PATCH v2 2/2] staging: gs_fpgaboot: change char to u8

On Mon, Jul 17, 2017 at 06:22:08PM -0700, Joe Perches wrote:
> read_bitstream takes an int rdsize, not a u16.
> and this function will overflow tbuf if len > 64
>
> static void readinfo_bitstream(char *bitdata, char *buf, int *offset)
> {
> 	char tbuf[64];
> 	s32 len;
> 
> 	/* read section char */
> 	read_bitstream(bitdata, tbuf, offset, 1);
> 
> 	/* read length */
> 	read_bitstream(bitdata, tbuf, offset, 2);
> 
> 	len = tbuf[0] << 8 | tbuf[1];
> 
> 	read_bitstream(bitdata, buf, offset, len);
> 	buf[len] = '\0';
> }
> 
> len is up to 64k but tbuf is 64 bytes.

tbuf is used here to read a total of 3 bytes over two calls to
read_bitstream. The larger read of size, len, is stored to buf which is
MAX_STR bytes in length. 

> 	len = get_unaligned_le16(tbuf)
> 
> might be nicer than
> 
> 	len = tbuf[0] << 8 | tbuf[1];

Agreed, though it should be "get_unaligned_be16". 

Thanks.

Regards,
Jacob von Chorus