On Mon, Oct 19, 2020 at 03:46:39PM +0000, Martijn de Gouw wrote: > Hi > > On 19-10-2020 17:23, J. Bruce Fields wrote: > > On Mon, Oct 19, 2020 at 01:42:27PM +0200, Martijn de Gouw wrote: > >> When the passed token is longer than 4032 bytes, the remaining part > >> of the token must be copied from the rqstp->rq_arg.pages. But the > >> copy must make sure it happens in a consecutive way. > > > > Thanks. Apologies, but I don't immediately see where the copy is > > non-consecutive. What exactly is the bug in the existing code? > > In the first memcpy 'length' bytes are copied from argv->iobase, but > since the header is in front, this never fills the whole first page of > in_token->pages. > > The memcpy in the loop copies the following bytes, but starts writing at > the next page of in_token->pages. This leaves the last bytes of page 0 > unwritten. > > Next to that, the remaining data is in page 0 of rqstp->rq_arg.pages, > not page 1. Got it, thanks. Looks like the culprit might be a patch from a year ago from Chuck, 5866efa8cbfb "SUNRPC: Fix svcauth_gss_proxy_init()"? At least, that's the last major patch to touch this code. --b. > > Regards, Martijn > > > > > --b. > > > >> > >> Signed-off-by: Martijn de Gouw <martijn.de.gouw@xxxxxxxxxxxxxxxxxxxxxxxxx> > >> --- > >> net/sunrpc/auth_gss/svcauth_gss.c | 27 +++++++++++++++++---------- > >> 1 file changed, 17 insertions(+), 10 deletions(-) > >> > >> diff --git a/net/sunrpc/auth_gss/svcauth_gss.c b/net/sunrpc/auth_gss/svcauth_gss.c > >> index 258b04372f85..bd4678db9d76 100644 > >> --- a/net/sunrpc/auth_gss/svcauth_gss.c > >> +++ b/net/sunrpc/auth_gss/svcauth_gss.c > >> @@ -1147,9 +1147,9 @@ static int gss_read_proxy_verf(struct svc_rqst *rqstp, > >> struct gssp_in_token *in_token) > >> { > >> struct kvec *argv = &rqstp->rq_arg.head[0]; > >> - unsigned int page_base, length; > >> - int pages, i, res; > >> - size_t inlen; > >> + unsigned int length, pgto_offs, pgfrom_offs; > >> + int pages, i, res, pgto, pgfrom; > >> + size_t inlen, to_offs, from_offs; > >> > >> res = gss_read_common_verf(gc, argv, authp, in_handle); > >> if (res) > >> @@ -1177,17 +1177,24 @@ static int gss_read_proxy_verf(struct svc_rqst *rqstp, > >> memcpy(page_address(in_token->pages[0]), argv->iov_base, length); > >> inlen -= length; > >> > >> - i = 1; > >> - page_base = rqstp->rq_arg.page_base; > >> + to_offs = length; > >> + from_offs = rqstp->rq_arg.page_base; > >> while (inlen) { > >> - length = min_t(unsigned int, inlen, PAGE_SIZE); > >> - memcpy(page_address(in_token->pages[i]), > >> - page_address(rqstp->rq_arg.pages[i]) + page_base, > >> + pgto = to_offs >> PAGE_SHIFT; > >> + pgfrom = from_offs >> PAGE_SHIFT; > >> + pgto_offs = to_offs & ~PAGE_MASK; > >> + pgfrom_offs = from_offs & ~PAGE_MASK; > >> + > >> + length = min_t(unsigned int, inlen, > >> + min_t(unsigned int, PAGE_SIZE - pgto_offs, > >> + PAGE_SIZE - pgfrom_offs)); > >> + memcpy(page_address(in_token->pages[pgto]) + pgto_offs, > >> + page_address(rqstp->rq_arg.pages[pgfrom]) + pgfrom_offs, > >> length); > >> > >> + to_offs += length; > >> + from_offs += length; > >> inlen -= length; > >> - page_base = 0; > >> - i++; > >> } > >> return 0; > >> } > >> -- > >> 2.20.1 > > -- > Martijn de Gouw > Designer > Prodrive Technologies > Mobile: +31 63 17 76 161 > Phone: +31 40 26 76 200