Vulnerability in Linux

[ Description ]Official description

In the Linux kernel, the following vulnerability has been resolved: mm: filemap: retain mapped dropbehind folios Fault-around can map ready dropbehind folios without going through the normal page-cache lookup that clears dropbehind. A mapping represents a competing cached user, so retain the folio instead of forcibly unmapping it when writeback completes. For a mapped folio, folio_unmap_invalidate() can call unmap_mapping_folio(), which takes i_mmap_rwsem and may sleep. Retaining mapped folios avoids this path when folio_end_dropbehind() runs in non-preemptible task context. Tal was able to trigger a sleeping-in-atomic warning due to this [1]. Unmapped dropbehind folios continue through the existing invalidation path.

[ Fixes ]Fixes and patches

No fix or interim patch is linked from our sources yet. Check the vendor references below and limit exposure of affected systems until a fix is available.

[ Advisories ]Government CERT advisories

• BSI CERT-Bund5 Oct 2026WID-SEC-2026-3743

  Linux Kernel: Multiple vulnerabilities Translated from German

  Risk mediumCVE-2026-98221CVE-2026-98181CVE-2026-98248+204 more CVEs

[ References ]References

• git.kernel.org/stable/c/2897601dffe576fcd87a4259102f41f7fb0cbfc8
• git.kernel.org/stable/c/77c0fade37c80e8aa16ac048a9828249055e3f66
• git.kernel.org/stable/c/848d2ce2fce15fbdc083fbf9691bfa72911033c4