CVE-2026-90384

In the Linux kernel, the following vulnerability has been resolved:

iomap: release the folio batch on iomap callback failures

A sashiko review of an unrelated patch points out that the folio

batch mechanism used for iomap zero range fails to release the batch

in a couple error scenarios. If either calls to ->iomap_end() or

->iomap_begin() fail, the direct return paths bypass the batch

cleanup.

The ->iomap_end() case is not a practical issue at the moment

because there is no user of the mechanism that returns an error from

this path. The ->iomap_begin() case is theoretically possible

because XFS can invoke the fill helper and error out at various

points thereafter. This subtly complicates things because XFS does

not transfer iomap_flags to the iomap data structure in the error

path.

To deal with both of these issues, first make sure to invoke the

cleanup helper in the error path for either fs callback. Second,

update the helper to clear the flag unconditionally and release the

batch so long as it is populated. This more clearly delineates the

purpose of the flag to control the I/O path and not necessarily the

status of the fbatch, so add a comment around this as well.