On Thu, Sep 05, 2019 at 03:40:32PM +1000, Herbert Xu wrote: > On Wed, Sep 04, 2019 at 10:22:17PM -0700, Eric Biggers wrote: > > > > Okay, but what about external callers that pass in an error? (I mean, I don't > > actually see any currently, but the point of this patch is to allow it...) > > What would prevent the crash in scatterwalk_done() in that case? > > With external callers the pages are always mapped and therefore > they have to be unmapped, regardless of whether the actual crypto > succeeded or not. > That's not what I'm talking about. I'm talking about flushing the page, in scatterwalk_done(). It assumes the page that was just processed was: sg_page(walk->sg) + ((walk->offset - 1) >> PAGE_SHIFT) But if no bytes were processed, this is invalid. Notably, if no bytes were processed then walk->offset can be 0, causing a crash. - Eric
