CVE-2025-22020: kernel: memstick: rtsx_usb_ms: Fix slab-use-after-free in rtsx_usb_ms_drv_remove
Component: kernel
Severity: Moderate
CWE: CWE-416 (Use After Free)
CVSS v3: 7.8 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H)
Public date: 2025-04-16T00:00:00+00:00

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

memstick: rtsx_usb_ms: Fix slab-use-after-free in rtsx_usb_ms_drv_remove

This fixes the following crash:

==================================================================
BUG: KASAN: slab-use-after-free in rtsx_usb_ms_poll_card+0x159/0x200 [rtsx_usb_ms]
Read of size 8 at addr ffff888136335380 by task kworker/6:0/140241

CPU: 6 UID: 0 PID: 140241 Comm: kworker/6:0 Kdump: loaded Tainted: G            E      6.14.0-rc6+ #1
Tainted: [E]=UNSIGNED_MODULE
Hardware name: LENOVO 30FNA1V7CW/1057, BIOS S0EKT54A 07/01/2024
Workqueue: events rtsx_usb_ms_poll_card [rtsx_usb_ms]
Call Trace:
 <TASK>
 dump_stack_lvl+0x51/0x70
 print_address_description.constprop.0+0x27/0x320
 ? rtsx_usb_ms_poll_card+0x159/0x200 [rtsx_usb_ms]
 print_report+0x3e/0x70
 kasan_report+0xab/0xe0
 ? rtsx_usb_ms_poll_card+0x159/0x200 [rtsx_usb_ms]
 rtsx_usb_ms_poll_card+0x159/0x200 [rtsx_usb_ms]
 ? __pfx_rtsx_usb_ms_poll_card+0x10/0x10 [rtsx_usb_ms]
 ? __pfx___schedule+0x10/0x10
 ? kick_pool+0x3b/0x270
 process_one_work+0x357/0x660
 worker_thread+0x390/0x4c0
 ? __pfx_worker_thread+0x10/0x10
 kthread+0x190/0x1d0
 ? __pfx_kthread+0x10/0x10
 ret_from_fork+0x2d/0x50
 ? __pfx_kthread+0x10/0x10
 ret_from_fork_asm+0x1a/0x30
 </TASK>

Allocated by task 161446:
 kasan_save_stack+0x20/0x40
 kasan_save_track+0x10/0x30
 __kasan_kmalloc+0x7b/0x90
 __kmalloc_noprof+0x1a7/0x470
 memstick_alloc_host+0x1f/0xe0 [memstick]
 rtsx_usb_ms_drv_probe+0x47/0x320 [rtsx_usb_ms]
 platform_probe+0x60/0xe0
 call_driver_probe+0x35/0x120
 really_probe+0x123/0x410
 __driver_probe_device+0xc7/0x1e0
 driver_probe_device+0x49/0xf0
 __device_attach_driver+0xc6/0x160
 bus_for_each_drv+0xe4/0x160
 __device_attach+0x13a/0x2b0
 bus_probe_device+0xbd/0xd0
 device_add+0x4a5/0x760
 platform_device_add+0x189/0x370
 mfd_add_device+0x587/0x5e0
 mfd_add_devices+0xb1/0x130
 rtsx_usb_probe+0x28e/0x2e0 [rtsx_usb]
 usb_probe_interface+0x15c/0x460
 call_driver_probe+0x35/0x120
 really_probe+0x123/0x410
 __driver_probe_device+0xc7/0x1e0
 driver_probe_device+0x49/0xf0
 __device_attach_driver+0xc6/0x160
 bus_for_each_drv+0xe4/0x160
 __device_attach+0x13a/0x2b0
 rebind_marked_interfaces.isra.0+0xcc/0x110
 usb_reset_device+0x352/0x410
 usbdev_do_ioctl+0xe5c/0x1860
 usbdev_ioctl+0xa/0x20
 __x64_sys_ioctl+0xc5/0xf0
 do_syscall_64+0x59/0x170
 entry_SYSCALL_64_after_hwframe+0x76/0x7e

Freed by task 161506:
 kasan_save_stack+0x20/0x40
 kasan_save_track+0x10/0x30
 kasan_save_free_info+0x36/0x60
 __kasan_slab_free+0x34/0x50
 kfree+0x1fd/0x3b0
 device_release+0x56/0xf0
 kobject_cleanup+0x73/0x1c0
 rtsx_usb_ms_drv_remove+0x13d/0x220 [rtsx_usb_ms]
 platform_remove+0x2f/0x50
 device_release_driver_internal+0x24b/0x2e0
 bus_remove_device+0x124/0x1d0
 device_del+0x239/0x530
 platform_device_del.part.0+0x19/0xe0
 platform_device_unregister+0x1c/0x40
 mfd_remove_devices_fn+0x167/0x170
 device_for_each_child_reverse+0xc9/0x130
 mfd_remove_devices+0x6e/0xa0
 rtsx_usb_disconnect+0x2e/0xd0 [rtsx_usb]
 usb_unbind_interface+0xf3/0x3f0
 device_release_driver_internal+0x24b/0x2e0
 proc_disconnect_claim+0x13d/0x220
 usbdev_do_ioctl+0xb5e/0x1860
 usbdev_ioctl+0xa/0x20
 __x64_sys_ioctl+0xc5/0xf0
 do_syscall_64+0x59/0x170
 entry_SYSCALL_64_after_hwframe+0x76/0x7e

Last potentially related work creation:
 kasan_save_stack+0x20/0x40
 kasan_record_aux_stack+0x85/0x90
 insert_work+0x29/0x100
 __queue_work+0x34a/0x540
 call_timer_fn+0x2a/0x160
 expire_timers+0x5f/0x1f0
 __run_timer_base.part.0+0x1b6/0x1e0
 run_timer_softirq+0x8b/0xe0
 handle_softirqs+0xf9/0x360
 __irq_exit_rcu+0x114/0x130
 sysvec_apic_timer_interrupt+0x72/0x90
 asm_sysvec_apic_timer_interrupt+0x16/0x20

Second to last potentially related work creation:
 kasan_save_stack+0x20/0x40
 kasan_record_aux_stack+0x85/0x90
 insert_work+0x29/0x100
 __queue_work+0x34a/0x540
 call_timer_fn+0x2a/0x160
 expire_timers+0x5f/0x1f0
 __run_timer_base.part.0+0x1b6/0x1e0
 run_timer_softirq+0x8b/0xe0
 handle_softirqs+0xf9/0x
---truncated---

Statement: This vulnerability is caused by a race condition between the driver removal routine and a periodically scheduled work function (`poll_card`). It can be triggered by attaching and then removing a USB device, which in turn calls the removal subroutine, which runs before ensuring that the `poll_card` work item is canceled. 

If done physically, then the attack requires no particular user privileges. However, implementing a programmatic version of this vulnerability would require elevated privileges (e.g. `CAP_SYS_ADMIN`) as it would require driver unbinding and/or device removal.

Affected upstream versions: 5.0
Fixed upstream versions: 0, 5.10.236, 5.15.180, 5.4.292, 6.1.133, 6.12.22, 6.13.10, 6.14.1, 6.15, 6.6.86
Upstream repository: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Upstream fix commit: 914c5e5bfceb9878f3056eaf4d1c88f2cbe0a185