CVE-2026-98443xfs: fix cursor and pointer handling when recovering iunlink buckets

Official description

In the Linux kernel, the following vulnerability has been resolved: xfs: fix cursor and pointer handling when recovering iunlink buckets LOLLM pointed out a bug in xlog_recover_iunlink_bucket: 1. We don't null out prev_ip after releasing it, which can lead to UAF problems if the inodegc flush call in the loop fails. at which point I noticed even more bugs: 2. If the inodegc flush inside the loop fails, we also leak @ip. 3. We set prev_agino to agino having already advanced agino, which results in inodes with i_prev_unlinked set to itself. 4. If we exit the bottom of the loop with prev_ip set, then prev_ip aliases ip and we also set its i_prev_unlinked to itself. Bugs 3 and 4 introduce loops into the unlinked list, though these loops don't surface because we immediately flush each unlinked inode after loading it. Fix all of these issues.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/8cfde7b2fb7288f4f6b90293e8702ff897c682fe
• https://git.kernel.org/stable/c/47a948ba653a463d429e02fda2f06a3d6b78666d
• https://git.kernel.org/stable/c/8c9d5b8a96d6b93eb24e07b4163c89341ba29bd1
• https://git.kernel.org/stable/c/66a2179d02668f8df44b1a249899006f3ba38ea0
• https://git.kernel.org/stable/c/961c717e6bf0e53c2c2b1fe4aef1add9390fedab
• https://git.kernel.org/stable/c/65f39d09d73718611cee40399179323b5d4ead00