Bug#1120598: ls input/output error ("NFS: readdir(/) returns -5") on krb5 NFSv4 client using SHA2

From	"Tyler W. Ross" <TWR@tylerwross.com>
Newsgroups	linux.debian.bugs.dist, linux.kernel, linux.debian.kernel
Subject	Bug#1120598: ls input/output error ("NFS: readdir(/) returns -5") on krb5 NFSv4 client using SHA2
Date	2025-11-13 20:00 +0100
Message-ID	<LQKI1-cIMi-5@gated-at.bofh.it> (permalink)
References	(4 earlier) <LQJVD-cIsP-3@gated-at.bofh.it> <LQJVD-cIsP-1@gated-at.bofh.it> <LQKI1-cIMi-7@gated-at.bofh.it> <LQqSZ-cvae-3@gated-at.bofh.it> <LQKI1-cIMi-7@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Cross-posted to 3 groups.

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On Thursday, November 13th, 2025 at 11:12 AM, Chuck Lever <chuck.lever@oracle.com> wrote:

> Then I would start looking for differences between the Debian 13 and
> Fedora 43 kernel code base under net/sunrpc/ .
> 
> Alternatively, "git bisect first, ask questions later" ... :-)

This is outside my day-to-day, so I don't have a workflow for this kind of
testing/debugging, but I'll see what I can do.

Thanks for the starting place.

> So I didn't find an indication of whether this was sec=krb5, sec=krb5i,
> or sec=krb5p. That might narrow down where the code changed.

I confirmed the issue with all 3 krb5 sec modes, in both the 6.12 kernel
that ships with Debian 13 and the 6.17 that currently ships with Debian
Sid/unstable. Similarly, I confirmed NFSv4.2, 4.1 and 4.0 are impacted.

> Also, the xdr_buf might have a page boundary positioned in the middle of
> an XDR data item. Knowing which data item is being decoded where the
> "overflow" occurs might be helpful (I think adding pr_info() call sites
> or trace_printk() will be adequate to gain some better observability).

No experience with kernel hacking, so I'm not confident I can locate
meaningful places to insert those.

I'll see where some snooping and a bisect gets me. Failing that, if
anyone has recommendations on where to add those calls, I'd appreciate
the guidance.

TWR

Thread

Bug#1120598: nfs-common: ls input/output error ("NFS: readdir(/) returns -5") on krb5 NFSv4 client using SHA2 "Tyler W. Ross" <twr+debbugs@tylerwross.com> - 2025-11-12 22:50 +0100
  Bug#1120598: ls input/output error ("NFS: readdir(/) returns -5") on krb5 NFSv4 client using SHA2 Salvatore Bonaccorso <carnil@debian.org> - 2025-11-13 06:10 +0100
  Bug#1120598: ls input/output error ("NFS: readdir(/) returns -5") on krb5 NFSv4 client using SHA2 "Tyler W. Ross" <TWR@tylerwross.com> - 2025-11-13 18:20 +0100
  Bug#1120598: ls input/output error ("NFS: readdir(/) returns -5") on krb5 NFSv4 client using SHA2 "Tyler W. Ross" <TWR@tylerwross.com> - 2025-11-13 19:10 +0100
  Bug#1120598: ls input/output error ("NFS: readdir(/) returns -5") on krb5 NFSv4 client using SHA2 "Tyler W. Ross" <TWR@tylerwross.com> - 2025-11-13 20:00 +0100
  Bug#1120598: ls input/output error ("NFS: readdir(/) returns -5") on krb5 NFSv4 client using SHA2 "Tyler W. Ross" <TWR@tylerwross.com> - 2025-11-14 05:40 +0100
    Bug#1120598: ls input/output error ("NFS: readdir(/) returns -5") on krb5 NFSv4 client using SHA2 "Tyler W. Ross" <TWR@tylerwross.com> - 2025-11-14 06:20 +0100
  Bug#1120598: ls input/output error ("NFS: readdir(/) returns -5") on krb5 NFSv4 client using SHA2 "Tyler W. Ross" <TWR@tylerwross.com> - 2025-11-16 01:50 +0100
  Bug#1120598: ls input/output error ("NFS: readdir(/) returns -5") on krb5 NFSv4 client using SHA2 Trond Myklebust <trondmy@kernel.org> - 2025-11-16 19:30 +0100
    Bug#1120598: ls input/output error ("NFS: readdir(/) returns -5") on krb5 NFSv4 client using SHA2 "Tyler W. Ross" <TWR@tylerwross.com> - 2025-11-17 06:30 +0100
      Bug#1120598: ls input/output error ("NFS: readdir(/) returns -5") on krb5 NFSv4 client using SHA2 Scott Mayhew <smayhew@redhat.com> - 2025-11-18 00:10 +0100
    Bug#1120598: ls input/output error ("NFS: readdir(/) returns -5") on krb5 NFSv4 client using SHA2 Scott Mayhew <smayhew@redhat.com> - 2025-11-18 00:10 +0100
      Bug#1120598: ls input/output error ("NFS: readdir(/) returns -5") on krb5 NFSv4 client using SHA2 "Tyler W. Ross" <TWR@tylerwross.com> - 2025-11-18 05:20 +0100
        Bug#1120598: ls input/output error ("NFS: readdir(/) returns -5") on krb5 NFSv4 client using SHA2 Scott Mayhew <smayhew@redhat.com> - 2025-11-18 19:00 +0100
          Bug#1120598: ls input/output error ("NFS: readdir(/) returns -5") on krb5 NFSv4 client using SHA2 "Tyler W. Ross" <TWR@tylerwross.com> - 2025-11-19 00:50 +0100
  Bug#1120598: ls input/output error ("NFS: readdir(/) returns -5") on krb5 NFSv4 client using SHA2 "Tyler W. Ross" <TWR@tylerwross.com> - 2025-11-17 19:50 +0100
  Bug#1120598: ls input/output error ("NFS: readdir(/) returns -5") on krb5 NFSv4 client using SHA2 "Tyler W. Ross" <TWR@tylerwross.com> - 2025-11-18 05:40 +0100
  Bug#1120598: ls input/output error ("NFS: readdir(/) returns -5") on krb5 NFSv4 client using SHA2 Scott Mayhew <smayhew@redhat.com> - 2025-11-19 14:40 +0100
  Bug#1120598: ls input/output error ("NFS: readdir(/) returns -5") on krb5 NFSv4 client using SHA2 "Tyler W. Ross" <TWR@tylerwross.com> - 2025-11-19 18:30 +0100
  Bug#1120598: marked as done (nfs: ls input/output error ("NFS:  readdir(/) returns -5") on krb5 NFSv4 client using SHA2) "Debian Bug Tracking System" <owner@bugs.debian.org> - 2026-03-09 22:10 +0100

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