mmc: mtk-sd: Cancel request timeout work on remove

Overview

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

mmc: mtk-sd: Cancel request timeout work on remove

The driver queues req_timeout while a request is active. msdc_request_done() uses cancel_delayed_work(), which does not wait for a timeout callback that has already started.

The timeout callback calls mmc_request_done(), which wakes the request waiter, and then continues to use host->dev_comp and check the SDIO IRQ. During unbind, msdc_drv_remove() can return and the managed mmc_host can be freed before the callback finishes.

KASAN reported use-after-free accesses in msdc_request_done() and msdc_recheck_sdio_irq() in each of three unbind tests. The same tests completed without a kernel diagnostic after this change.

Call cancel_delayed_work_sync() after mmc_remove_host() has stopped new requests and before the driver releases the host resources.

Affected

• Linux >= 208489032bdd8d4a7de50f3057c175058f271956 < 9e799f25c420e759641eb25102967ea091fc758f
• Linux >= 208489032bdd8d4a7de50f3057c175058f271956 < f37e0367ad6f2147a0b37564b442b7a25bec0d23
• Linux >= 208489032bdd8d4a7de50f3057c175058f271956 < 46e75703ca3f00fb8c935b3ce35b90836e34e8af
• Linux >= 208489032bdd8d4a7de50f3057c175058f271956 < edef1355224c0799a502a46b71d3649fa0dd218e
• Linux >= 208489032bdd8d4a7de50f3057c175058f271956 < b38af5386a74416e898955443f2e26547b358cb2
• Linux 4.2

Remediation

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