[Bug 2173036] Re: Tasks can hang forever when using NFSv4 with the sec=krb5 mount option

** Tags added: kernel-daily-bug -- You received this bug notification because you are subscribed to linux in Ubuntu. Matching subscriptions: Bgg, Bmail, Nb https://bugs.launchpad.net/bugs/2173036 Title: Tasks can hang forever when using NFSv4 with the sec=krb5 mount option Status in linux package in Ubuntu: Invalid Status in linux source package in Jammy: In Progress Status in linux source package in Noble: In Progress Bug description: [Impact] NFSv3 and v4 clients using a sec=krb5* mount option can run into a situation where the GSS context expires between sending a request and verifying its reply, causing gss_validate() to fail with GSS_S_CONTEXT_EXPIRED. This results in an EACCES error returned from gss_validate(), which behaves differently on Jammy vs Noble: On Jammy 5.15 kernels, this results in an I/O error being returned. On Noble 6.8 kernels (version 6.8.0-98 and later), because commit fadc0f3bb2de ("sunrpc: don't immediately retransmit on seqno miss") was backported without 9b62ef6d239e ("SUNRPC: fix handling expired GSS context"), the client discards the reply, which results in the task issuing the request never seeing that reply and thus hanging indefinitely. [Fix] The fix exists upstream as commit 9b62ef6d239e ("SUNRPC: fix handling expired GSS context"). The fix solves the issue by catching an error caused by an expired auth context and in that scenario, returning EKEYREJECTED, which triggers the caller to obtain new context and retry instead of stalling. This is a clean cherry pick to Noble 6.8 and Jammy 5.15. [Test plan] Build and boot tested. [Where issues could occur] This modifies the SUNRPC client implementation. Regressions could occur in either it or users of it, including NFSv3 and v4 mounts using Kerberos. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2173036/+subscriptions