Re: [PATCH v2] staging: erofs: keep corrupted fs from crashing kernel in erofs_namei()

[Dan Carpenter]

On Fri, Feb 15, 2019 at 05:32:33PM +0800, Chao Yu wrote:
> On 2019/2/15 15:57, Dan Carpenter wrote:
> > On Fri, Feb 15, 2019 at 03:02:25PM +0800, Chao Yu wrote:
> >> On 2019/2/1 20:16, Gao Xiang wrote:
> >>> +	/*
> >>> +	 * on-disk error, let's only BUG_ON in the debugging mode.
> >>> +	 * otherwise, it will return 1 to just skip the invalid name
> >>> +	 * and go on (in consideration of the lookup performance).
> >>> +	 */
> >>> +	DBG_BUGON(qd->name > qd->end);
> >>
> >> qd->name == qd->end is not allowed as well?
> >>
> >> So will it be better to return directly here?
> >>
> >> 	if (unlikely(qd->name >= qd->end)) {
> >> 		DBG_BUGON(1);
> >> 		return 1;
> >> 	}
> > 
> > Please don't add likely/unlikely() annotations unless you have
> > benchmarked it and it makes a difference.
> 
> Well, it only occur for corrupted image, since the image is readonly, so it
> is really rare.

The likely/unlikely() annotations make the code harder to read.  It's
only worth it if it's is a speedup on a fast path.

regards,
dan carpenter