ext4: don't enable large folios on encrypted inodes

Overview

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

ext4: don't enable large folios on encrypted inodes

Commit 709f0f1f1bf5 ("ext4: add checks for large folio incompatibilities when BS > PS") disables large folios at mount time if the "encrypt" feature is set. However, enabling that feature on a mounted filesystem circumvents that check, and writing encrypted data results in a crash:

BUG: kernel NULL pointer dereference, address: 0000000000000028 Workqueue: ext4-rsv-conversion ext4_end_io_rsv_work RIP: 0010:ext4_finish_bio+0xf7/0x3e0 Call Trace: ext4_release_io_end+0x51/0x110 ext4_end_io_end+0x4c/0xe0 ext4_end_io_rsv_work+0xb3/0x100

Fix this by disabling large folios on encrypted inodes, as is already done for inodes that use data journaling.

This affects all kernels between v6.19 and v7.2, but it is not needed in v7.3, where the code was significantly refactored.

Affected

• Linux >= 709f0f1f1bf5ca62a000084e5446ca6b57c8678c < 40554d1221e3d2ff2e0d192b74a05d89eb3620e7
• Linux 6.19

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.