CVE-2026-99039

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

memstick: core: wait for request completion before freeing card

In memstick_alloc_card() and memstick_set_rw_addr(), wait_for_completion_timeout() is used to wait for device identification and address configuration requests to complete.

The memstick subsystem does not provide an abort or cancellation callback in struct memstick_host for in-flight requests. If wait_for_completion_timeout() expires (for instance, when a USB transfer or command retry is delayed), memstick_alloc_card() returns an error and frees the memstick_dev structure via kfree(card).

However, the host controller driver (such as rtsx_usb_ms) is still running the request asynchronously in worker context. When the transfer eventually finishes, the driver writes into host->req->data, which points to memory inside the already freed card structure. This leads to a KASAN slab-use-after-free write:

BUG: KASAN: slab-use-after-free in ms_read_bytes+0x8fe/0x990 Write of size 1 at addr ffff88813c188079 by task kworker/1:5/5239 Workqueue: events rtsx_usb_ms_handle_req Call Trace: ms_read_bytes+0x8fe/0x990 drivers/memstick/host/rtsx_usb_ms.c:450 rtsx_usb_ms_issue_cmd drivers/memstick/host/rtsx_usb_ms.c:477 [inline] rtsx_usb_ms_handle_req+0x557/0x1a00 drivers/memstick/host/rtsx_usb_ms.c:531 process_one_work+0xac7/0x1b10 kernel/workqueue.c:3396 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3560 kthread+0x373/0x450 kernel/kthread.c:436

Allocated by task 1662: memstick_alloc_card drivers/memstick/core/memstick.c:383 [inline] memstick_check+0x2c1/0x10d0 drivers/memstick/core/memstick.c:452 process_one_work+0xac7/0x1b10 kernel/workqueue.c:3396

Freed by task 1662: kfree+0x20c/0x650 mm/slub.c:6792 memstick_alloc_card drivers/memstick/core/memstick.c:420 [inline] memstick_check+0x72b/0x10d0 drivers/memstick/core/memstick.c:452 process_one_work+0xac7/0x1b10 kernel/workqueue.c:3396

Host controller drivers (rtsx_usb_ms, jmb38x_ms, tifm_ms, r592) already implement their own hardware and bus timeouts, and callers in mspro_block and ms_block already rely on wait_for_completion() unconditionally.

Replace wait_for_completion_timeout() with wait_for_completion() in memstick_set_rw_addr() and memstick_alloc_card() so that the card structure is never freed while an asynchronous request is in flight.

Affected Software

References

• https://git.kernel.org/stable/c/1c23da6f148089d59b3d3e9b2e7f1eefa927cab9
• https://git.kernel.org/stable/c/3af81770e2011c6ac7bb597a4af2e4f3591f928c
• https://git.kernel.org/stable/c/810580cf60edc75c9891c2de3225e4cda78e4d9f
• https://git.kernel.org/stable/c/a2f1aa3341f185ca52103dc4908647570b208855
• https://git.kernel.org/stable/c/aa0a37b5024d921e96ac4f8f487c8bfbf1f1a582
• https://git.kernel.org/stable/c/b90f33ad9179c69658342323382bfed158f88cb9
• https://git.kernel.org/stable/c/c3ab92542475d59ae685cbb294e70ca4d0ba38e9
• https://git.kernel.org/stable/c/f2795c50144d528dabc2cf2fd53c0f0c63a823a1