In the Linux kernel, the following vulnerability has been resolved: iomap: avoid potential null folio->mapping deref during error reporting When a buffered read fails, iomap_finish_folio_read() reports the error with fserror_report_io(folio->mapping->host, ...). This is called after ifs->read_bytes_pending has been decremented by the bytes attempted to be read. For a folio split across multiple read completions, the folio is only guaranteed to stay locked while read_bytes_pending > 0. Once iomap_finish_folio_read() decrements read_bytes_pending, another in-flight read can complete and end the read on the folio, which unlocks it. This allows truncate logic to run and detach the folio (set folio->mapping to NULL). The error reporting path then can dereference a NULL folio->mapping. As reported by Sam Sun, this is the race that can occur: CPU0: failed completion CPU1: final completion CPU2: truncate ----------------------- ---------------------- -------------- read_bytes_pending -= len finished = false /* preempted before fserror_report_io() */ read_bytes_pending -= len finished = true folio_end_read() truncate clears folio->mapping fserror_report_io( folio->mapping->host, ...) ^ NULL deref Fix this by reporting the error first before decrementing ifs->read_bytes_pending.

A flaw was found in the Linux kernel's `iomap` subsystem. A race condition can occur during buffered read error reporting, specifically in the `iomap_finish_folio_read()` function. This allows a separate process to clear a folio's mapping while an error is being reported, leading to a null pointer dereference. This vulnerability can result in a system crash, causing a Denial of Service (DoS).

Red Hat Enterprise Linux 10 Not affected kernel Red Hat Enterprise Linux 6 Not affected kernel Red Hat Enterprise Linux 7 Not affected kernel Red Hat Enterprise Linux 7 Not affected kernel-rt Red Hat Enterprise Linux 8 Not affected kernel Red Hat Enterprise Linux 8 Not affected kernel-rt Red Hat Enterprise Linux 9 Not affected kernel Red Hat Enterprise Linux 9 Not affected kernel-rt https://www.cve.org/CVERecord?id=CVE-2026-53165 https://nvd.nist.gov/vuln/detail/CVE-2026-53165 https://lore.kernel.org/linux-cve-announce/2026062550-CVE-2026-53165-7592@gregkh/T