> On Sep 1, 2021, at 7:30 PM, NeilBrown <neilb@xxxxxxx> wrote: > > > When the NFS server receives a large gss (kerberos) credential and tries > to pass it up to rpc.svcgssd (which is deprecated), it triggers an > infinite loop in cache_read(). > > cache_request() always returns -EAGAIN, and this causes a "goto again". > > This patch: > - changes the error to -E2BIG to avoid the infinite loop, and > - generates a WARN_ONCE when rsi_request first sees an over-sized > credential. The warning suggests switching to gssproxy. > > Link: https://bugzilla.kernel.org/show_bug.cgi?id=196583 > Signed-off-by: NeilBrown <neilb@xxxxxxx> Thanks, Neil, I've queued this up for nfsd-5.15-1. > --- > net/sunrpc/auth_gss/svcauth_gss.c | 2 ++ > net/sunrpc/cache.c | 2 +- > 2 files changed, 3 insertions(+), 1 deletion(-) > > diff --git a/net/sunrpc/auth_gss/svcauth_gss.c b/net/sunrpc/auth_gss/svcauth_gss.c > index a81be45f40d9..e738c0182f09 100644 > --- a/net/sunrpc/auth_gss/svcauth_gss.c > +++ b/net/sunrpc/auth_gss/svcauth_gss.c > @@ -194,6 +194,8 @@ static void rsi_request(struct cache_detail *cd, > qword_addhex(bpp, blen, rsii->in_handle.data, rsii->in_handle.len); > qword_addhex(bpp, blen, rsii->in_token.data, rsii->in_token.len); > (*bpp)[-1] = '\n'; > + WARN_ONCE(*blen < 0, > + "RPCSEC/GSS credential too large - please use gssproxy\n"); > } > > static int rsi_parse(struct cache_detail *cd, > diff --git a/net/sunrpc/cache.c b/net/sunrpc/cache.c > index 1a2c1c44bb00..59641803472c 100644 > --- a/net/sunrpc/cache.c > +++ b/net/sunrpc/cache.c > @@ -803,7 +803,7 @@ static int cache_request(struct cache_detail *detail, > > detail->cache_request(detail, crq->item, &bp, &len); > if (len < 0) > - return -EAGAIN; > + return -E2BIG; > return PAGE_SIZE - len; > } > > -- > 2.32.0 > -- Chuck Lever
