Re: [WT PATCH 6/6] mac80211: Tell user why beacons fail to parse.

[Johannes Berg <johannes@sipsolutions.net>]

On Thu, 2013-07-11 at 08:10 -0700, Ben Greear wrote:

> >>   	/* Keep track of what bits of information we have valid info for. */
> >>   	u8 valid_data;
> >> +	char corrupt_elems_msg[80];
> >
> > you should store a "what's bad" type field and the broken IE number or
> > so, to reduce memory usage
> 
> I thought of this, but the problem is then you cannot tell the details
> (for instance the actual lengths when length is bad, the ID that is duplicated, etc).
> I figure if we are going to provide the info to the user, we might as well
> be specific about it.

It doesn't seem so difficult?

enum ies_parse_error {
	NO_ERROR,
	BAD_IE_LEN, // uses eid+len
	DUPLICATE_IE, // uses eid
	...
} parse_error;
int parse_error_eid, parse_error_len;

> >> +				snprintf(elems->parse_err_msg,
> >> +					 sizeof(elems->parse_err_msg),
> >> +					 "seen id: %i already", id);
> >
> > Your snprintf() usage is also unsafe.
> 
> What is unsafe about it?

using printk("%s", result) is unsafe due to potentially missing
NUL-termination.

johannes