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. Fixes: baf8532a147d ("memstick: initial commit for Sony MemoryStick support") Reported-by: syzbot+ccffdf05833ebdaeae70@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=ccffdf05833ebdaeae70 Cc: stable@vger.kernel.org Signed-off-by: Raj Ojha --- drivers/memstick/core/memstick.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/drivers/memstick/core/memstick.c b/drivers/memstick/core/memstick.c index 7f3f47db4c98..1a2b3c4d5e6f 100644 --- a/drivers/memstick/core/memstick.c +++ b/drivers/memstick/core/memstick.c @@ -378,9 +378,7 @@ int memstick_set_rw_addr(struct memstick_dev *card) { card->next_request = h_memstick_set_rw_addr; memstick_new_req(card->host); - if (!wait_for_completion_timeout(&card->mrq_complete, - msecs_to_jiffies(500))) - card->current_mrq.error = -ETIMEDOUT; + wait_for_completion(&card->mrq_complete); return card->current_mrq.error; } @@ -413,9 +411,7 @@ static struct memstick_dev *memstick_alloc_card(struct memstick_host *host) goto err_out; card->next_request = h_memstick_read_dev_id; memstick_new_req(host); - if (!wait_for_completion_timeout(&card->mrq_complete, - msecs_to_jiffies(500))) - card->current_mrq.error = -ETIMEDOUT; + wait_for_completion(&card->mrq_complete); if (card->current_mrq.error) goto err_out; -- 2.47.0.windows.1