RHEL Engineering is moving the tracking of its product development work on RHEL 6 through RHEL 9 to Red Hat Jira (issues.redhat.com). If you're a Red Hat customer, please continue to file support cases via the Red Hat customer portal. If you're not, please head to the "RHEL project" in Red Hat Jira and file new tickets here. Individual Bugzilla bugs in the statuses "NEW", "ASSIGNED", and "POST" are being migrated throughout September 2023. Bugs of Red Hat partners with an assigned Engineering Partner Manager (EPM) are migrated in late September as per pre-agreed dates. Bugs against components "kernel", "kernel-rt", and "kpatch" are only migrated if still in "NEW" or "ASSIGNED". If you cannot log in to RH Jira, please consult article #7032570. That failing, please send an e-mail to the RH Jira admins at rh-issues@redhat.com to troubleshoot your issue as a user management inquiry. The email creates a ServiceNow ticket with Red Hat. Individual Bugzilla bugs that are migrated will be moved to status "CLOSED", resolution "MIGRATED", and set with "MigratedToJIRA" in "Keywords". The link to the successor Jira issue will be found under "Links", have a little "two-footprint" icon next to it, and direct you to the "RHEL project" in Red Hat Jira (issue links are of type "https://issues.redhat.com/browse/RHEL-XXXX", where "X" is a digit). This same link will be available in a blue banner at the top of the page informing you that that bug has been migrated.
Bug 2172087 - fix accesses of inode->i_flctx
Summary: fix accesses of inode->i_flctx
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 9
Classification: Red Hat
Component: kernel
Version: 9.1
Hardware: Unspecified
OS: Unspecified
unspecified
medium
Target Milestone: rc
: ---
Assignee: Jeff Layton
QA Contact: Kun Wang
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2023-02-21 13:09 UTC by Jeff Layton
Modified: 2023-11-07 10:29 UTC (History)
7 users (show)

Fixed In Version: kernel-5.14.0-297.el9
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
Environment:
Last Closed: 2023-11-07 08:41:33 UTC
Type: Bug
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Gitlab redhat/centos-stream/src/kernel centos-stream-9 merge_requests 2075 0 None opened vfs: file locking fixes and cleanups for 9.3 2023-03-22 12:46:38 UTC
Red Hat Issue Tracker RHELPLAN-149519 0 None None None 2023-02-21 13:11:21 UTC
Red Hat Product Errata RHSA-2023:6583 0 None None None 2023-11-07 08:41:55 UTC

Description Jeff Layton 2023-02-21 13:09:43 UTC 
RHEL9 has a number of places that are accessing the inode->i_flctx field without using a smp_load_acquire. This is required to ensure that the caller doesn't see a partially-initialized structure.

Pull in commit 401a8b8fd5acd and the follow-on patches.
Comment 6 Jeff Layton 2023-03-21 14:16:04 UTC 
We may be technically breaking kABI with this patch:

2f6076aad206 fs/lock: add 2 callbacks to lock_manager_operations to resolve conflict

This grows the lock_manager_operations struct, so if anyone is using an out of tree lock manager (something akin to nfsd or lockd), then this could break for them. @bcodding thinks there might be a chance that GPFS is setting this field in some cases, and is going to try to confirm whether that's the case. That sounds wrong to me, but it's worth investigating before we merge this. Stay tuned.
Comment 9 Benjamin Coddington 2023-03-28 12:04:39 UTC 
(In reply to Jeff Layton from comment #6)
> This grows the lock_manager_operations struct, so if anyone is using an out
> of tree lock manager (something akin to nfsd or lockd), then this could
> break for them. @bcodding thinks there might be a chance that
> GPFS is setting this field in some cases, and is going to try to confirm
> whether that's the case. That sounds wrong to me, but it's worth
> investigating before we merge this. Stay tuned.

We did find gpfs is setting lm_ops in some cases, Jeff has modified the work to set a flag if we're going to be accessing the new offsets in the struct.  Its possible we don't need to technically do this due to the new kABI rules for RHEL-9, but doing it also makes things safer if older versions of modules are loaded.

It does seem like we should be able to restrict older/non-compatible out-of-tree-modules using structs that have changed with some versioning magic, but I'm not sure how that works.  Do we want to try to get a kABI SME to look at this?
Comment 18 errata-xmlrpc 2023-11-07 08:41:33 UTC 
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (Important: kernel security, bug fix, and enhancement update), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHSA-2023:6583
Note You need to log in before you can comment on or make changes to this bug.