Re: PROPOSAL: dot-proc interface [was: /proc stuff]

[Remco Post]

Hi,

still,

char name[80]
if (sscanf(line, "%4u %4u %llu %80s", &major, &minor, &size, name) == 4)

would safeguard you agains whatever you might read from your line, this is 
better protection agains buffer overflows than looking up the code that you 
think you'll be reading the output from. This code is NOT under your control, 
usually...

> On Tue Nov 06, 2001 at 02:49:23PM -0500, [e-mail] wrote:
> > In article <[e-mail]> Erik Anderson wrote:
> > > Come now, it really isn't that difficult: 
> > 
> > >    char name[80];
> > >    if (sscanf(line, "%4u %4u %llu %s", &major, &minor, &size, name) == 4)
> > 
> > if it's so easy to do, why do you have a great big buffer overflow here?
> 
> 
> Sorry, no doughnut for you.  drivers/block/genhd.c:
> 
>     #ifdef CONFIG_PROC_FS
>     int get_partition_list(char *page, char **start, off_t offset, int count)
>     {
> 	...
> 	char buf[64];
> 
> 	...
> 
> 	len += snprintf(page + len, 63, "%4d  %4d %10d %s\n", gp->major, n, 
> 		gp->sizes[n], disk_name(gp, n, buf));
> 
> so each /proc/partitions line maxes out at 63 bytes.  So not only
> is there no overflow, I am providing 16 extra bytes of padding.
> 
>  -Erik
> 
> --
> Erik B. Andersen             http://codepoet-consulting.com/
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-- 
Met vriendelijke groeten,

Remco Post

SARA - Stichting Academisch Rekencentrum Amsterdam
High Performance Computing  Tel. [phone]    Fax. [phone]

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