> On Sep 11, 2019, at 1:50 PM, Benjamin Coddington <bcodding@xxxxxxxxxx> wrote: > > On 11 Sep 2019, at 13:40, Benjamin Coddington wrote: > >> On 11 Sep 2019, at 13:29, Chuck Lever wrote: >> >>>> On Sep 11, 2019, at 1:26 PM, Benjamin Coddington <bcodding@xxxxxxxxxx> wrote: >>>> >>>> >>>> On 11 Sep 2019, at 12:39, Chuck Lever wrote: >>>> >>>>>> On Sep 11, 2019, at 12:25 PM, Benjamin Coddington <bcodding@xxxxxxxxxx> wrote: >>>>>> >>>> >>>>>> Instead, I think we want to make sure the mic falls squarely into the tail >>>>>> every time. >>>>> >>>>> I'm not clear how you could do that. The length of the page data is not >>>>> known to the client before it parses the reply. Are you suggesting that >>>>> gss_unwrap should do it somehow? >>>> >>>> Is it too niave to always put the mic at the end of the tail? >>> >>> The size of the page content is variable. >>> >>> The only way the MIC will fall into the tail is if the page content is >>> exactly the largest expected size. When the page content is smaller than >>> that, the receive logic will place part or all of the MIC in ->pages. >> >> Ok, right. But what I meant is that xdr_buf_read_netobj() should be renamed >> and repurposed to be "move the mic from wherever it is to the end of >> xdr_buf's tail". >> >> But now I see what you mean, and I also see that it is already trying to do >> that.. and we don't want to overlap the copy.. >> >> So, really, we need the tail to be larger than twice the mic.. less 1. That >> means the fix is probably just increasing rslack for krb5i. > > .. or we can keep the tighter tail space, and if we detect the mic straddles > the page and tail, we can move the mic into the tail with 2 copies, first > move the bit in the tail back, then move the bit in the pages. > > Which is preferred, less allocation, or in the rare case this occurs, doing > copy twice? It sounds like the bug is that the current code does not deal correctly when the MIC crosses the boundary between ->pages and ->tail? I'd like to see that addressed rather than changing rslack. -- Chuck Lever
