kernel/linux.git/drivers/usb/gadget/function/f_fs.c, branch v5.15.208

usb: gadget: f_fs: Fix epfile null pointer access after ep enable.

2025-12-06T21:09:15+00:00

commit cfd6f1a7b42f62523c96d9703ef32b0dbc495ba4 upstream. A race condition occurs when ffs_func_eps_enable() runs concurrently with ffs_data_reset(). The ffs_data_clear() called in ffs_data_reset() sets ffs->epfiles to NULL before resetting ffs->eps_count to 0, leading to a NULL pointer dereference when accessing epfile->ep in ffs_func_eps_enable() after successful usb_ep_enable(). The ffs->epfiles pointer is set to NULL in both ffs_data_clear() and ffs_data_close() functions, and its modification is protected by the spinlock ffs->eps_lock. And the whole ffs_func_eps_enable() function is also protected by ffs->eps_lock. Thus, add NULL pointer handling for ffs->epfiles in the ffs_func_eps_enable() function to fix issues Signed-off-by: Owen Gu Link: https://lore.kernel.org/r/20250915092907.17802-1-guhuinan@xiaomi.com Signed-off-by: Greg Kroah-Hartman

usb: gadget: f_fs: Remove WARN_ON in functionfs_bind

2025-01-23T16:15:54+00:00

commit dfc51e48bca475bbee984e90f33fdc537ce09699 upstream. This commit addresses an issue related to below kernel panic where panic_on_warn is enabled. It is caused by the unnecessary use of WARN_ON in functionsfs_bind, which easily leads to the following scenarios. 1.adb_write in adbd 2. UDC write via configfs ================= ===================== ->usb_ffs_open_thread() ->UDC write ->open_functionfs() ->configfs_write_iter() ->adb_open() ->gadget_dev_desc_UDC_store() ->adb_write() ->usb_gadget_register_driver_owner ->driver_register() ->StartMonitor() ->bus_add_driver() ->adb_read() ->gadget_bind_driver() ->configfs_composite_bind() ->usb_add_function() ->open_functionfs() ->ffs_func_bind() ->adb_open() ->functionfs_bind() state !=FFS_ACTIVE> The adb_open, adb_read, and adb_write operations are invoked from the daemon, but trying to bind the function is a process that is invoked by UDC write through configfs, which opens up the possibility of a race condition between the two paths. In this race scenario, the kernel panic occurs due to the WARN_ON from functionfs_bind when panic_on_warn is enabled. This commit fixes the kernel panic by removing the unnecessary WARN_ON. Kernel panic - not syncing: kernel: panic_on_warn set ... [ 14.542395] Call trace: [ 14.542464] ffs_func_bind+0x1c8/0x14a8 [ 14.542468] usb_add_function+0xcc/0x1f0 [ 14.542473] configfs_composite_bind+0x468/0x588 [ 14.542478] gadget_bind_driver+0x108/0x27c [ 14.542483] really_probe+0x190/0x374 [ 14.542488] __driver_probe_device+0xa0/0x12c [ 14.542492] driver_probe_device+0x3c/0x220 [ 14.542498] __driver_attach+0x11c/0x1fc [ 14.542502] bus_for_each_dev+0x104/0x160 [ 14.542506] driver_attach+0x24/0x34 [ 14.542510] bus_add_driver+0x154/0x270 [ 14.542514] driver_register+0x68/0x104 [ 14.542518] usb_gadget_register_driver_owner+0x48/0xf4 [ 14.542523] gadget_dev_desc_UDC_store+0xf8/0x144 [ 14.542526] configfs_write_iter+0xf0/0x138 Fixes: ddf8abd25994 ("USB: f_fs: the FunctionFS driver") Cc: stable Signed-off-by: Akash M Link: https://lore.kernel.org/r/20241219125221.1679-1-akash.m5@samsung.com Signed-off-by: Greg Kroah-Hartman

usb: gadget: f_fs: Fix race between aio_cancel() and AIO request complete

2024-07-05T07:14:09+00:00

[ Upstream commit 24729b307eefcd7c476065cd7351c1a018082c19 ] FFS based applications can utilize the aio_cancel() callback to dequeue pending USB requests submitted to the UDC. There is a scenario where the FFS application issues an AIO cancel call, while the UDC is handling a soft disconnect. For a DWC3 based implementation, the callstack looks like the following: DWC3 Gadget FFS Application dwc3_gadget_soft_disconnect() ... --> dwc3_stop_active_transfers() --> dwc3_gadget_giveback(-ESHUTDOWN) --> ffs_epfile_async_io_complete() ffs_aio_cancel() --> usb_ep_free_request() --> usb_ep_dequeue() There is currently no locking implemented between the AIO completion handler and AIO cancel, so the issue occurs if the completion routine is running in parallel to an AIO cancel call coming from the FFS application. As the completion call frees the USB request (io_data->req) the FFS application is also referencing it for the usb_ep_dequeue() call. This can lead to accessing a stale/hanging pointer. commit b566d38857fc ("usb: gadget: f_fs: use io_data->status consistently") relocated the usb_ep_free_request() into ffs_epfile_async_io_complete(). However, in order to properly implement locking to mitigate this issue, the spinlock can't be added to ffs_epfile_async_io_complete(), as usb_ep_dequeue() (if successfully dequeuing a USB request) will call the function driver's completion handler in the same context. Hence, leading into a deadlock. Fix this issue by moving the usb_ep_free_request() back to ffs_user_copy_worker(), and ensuring that it explicitly sets io_data->req to NULL after freeing it within the ffs->eps_lock. This resolves the race condition above, as the ffs_aio_cancel() routine will not continue attempting to dequeue a request that has already been freed, or the ffs_user_copy_work() not freeing the USB request until the AIO cancel is done referencing it. This fix depends on commit b566d38857fc ("usb: gadget: f_fs: use io_data->status consistently") Fixes: 2e4c7553cd6f ("usb: gadget: f_fs: add aio support") Cc: stable # b566d38857fc ("usb: gadget: f_fs: use io_data->status consistently") Signed-off-by: Wesley Cheng Link: https://lore.kernel.org/r/20240409014059.6740-1-quic_wcheng@quicinc.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin

usb: gadget: f_fs: use io_data->status consistently

2024-07-05T07:14:09+00:00

[ Upstream commit b566d38857fcb6777f25b674b90a831eec0817a2 ] Commit fb1f16d74e26 ("usb: gadget: f_fs: change ep->status safe in ffs_epfile_io()") added a new ffs_io_data::status field to fix lifetime issues in synchronous requests. While there are no similar lifetime issues for asynchronous requests (the separate ep member in ffs_io_data avoids them) using the status field means the USB request can be freed earlier and that there is more consistency between the synchronous and asynchronous I/O paths. Cc: Linyu Yuan Signed-off-by: John Keeping Reviewed-by: Linyu Yuan Link: https://lore.kernel.org/r/20221124170430.3998755-1-john@metanate.com Signed-off-by: Greg Kroah-Hartman Stable-dep-of: 24729b307eef ("usb: gadget: f_fs: Fix race between aio_cancel() and AIO request complete") Signed-off-by: Sasha Levin

usb: gadget: f_fs: Fix a race condition when processing setup packets.

2024-05-17T09:51:03+00:00

commit 0aea736ddb877b93f6d2dd8cf439840d6b4970a9 upstream. If the USB driver passes a pointer into the TRB buffer for creq, this buffer can be overwritten with the status response as soon as the event is queued. This can make the final check return USB_GADGET_DELAYED_STATUS when it shouldn't. Instead use the stored wLength. Fixes: 4d644abf2569 ("usb: gadget: f_fs: Only return delayed status when len is 0") Cc: stable Signed-off-by: Chris Wulff Link: https://lore.kernel.org/r/CO1PR17MB5419BD664264A558B2395E28E1112@CO1PR17MB5419.namprd17.prod.outlook.com Signed-off-by: Greg Kroah-Hartman

usb: gadget: f_fs: Add unbind event before functionfs_unbind

2023-06-09T08:32:29+00:00

commit efb6b535207395a5c7317993602e2503ca8cb4b3 upstream. While exercising the unbind path, with the current implementation the functionfs_unbind would be calling which waits for the ffs->mutex to be available, however within the same time ffs_ep0_read is invoked & if no setup packets are pending, it will invoke function wait_event_interruptible_exclusive_locked_irq which by definition waits for the ev.count to be increased inside the same mutex for which functionfs_unbind is waiting. This creates deadlock situation because the functionfs_unbind won't get the lock until ev.count is increased which can only happen if the caller ffs_func_unbind can proceed further. Following is the illustration: CPU1 CPU2 ffs_func_unbind() ffs_ep0_read() mutex_lock(ffs->mutex) wait_event(ffs->ev.count) functionfs_unbind() mutex_lock(ffs->mutex) mutex_unlock(ffs->mutex) ffs_event_add() Fix this by moving the event unbind before functionfs_unbind to ensure the ev.count is incrased properly. Fixes: 6a19da111057 ("usb: gadget: f_fs: Prevent race during ffs_ep0_queue_wait") Cc: stable Signed-off-by: Uttkarsh Aggarwal Link: https://lore.kernel.org/r/20230525092854.7992-1-quic_uaggarwa@quicinc.com Signed-off-by: Greg Kroah-Hartman

usb: gadget: f_fs: Fix unbalanced spinlock in __ffs_ep0_queue_wait

2023-02-09T10:26:40+00:00

[ Upstream commit 921deb9da15851425ccbb6ee409dc2fd8fbdfe6b ] __ffs_ep0_queue_wait executes holding the spinlock of &ffs->ev.waitq.lock and unlocks it after the assignments to usb_request are done. However in the code if the request is already NULL we bail out returning -EINVAL but never unlocked the spinlock. Fix this by adding spin_unlock_irq &ffs->ev.waitq.lock before returning. Fixes: 6a19da111057 ("usb: gadget: f_fs: Prevent race during ffs_ep0_queue_wait") Reviewed-by: John Keeping Signed-off-by: Udipto Goswami Link: https://lore.kernel.org/r/20230124091149.18647-1-quic_ugoswami@quicinc.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin

usb: gadget: f_fs: Ensure ep0req is dequeued before free_request

2023-02-01T07:27:11+00:00

[ Upstream commit ce405d561b020e5a46340eb5146805a625dcacee ] As per the documentation, function usb_ep_free_request guarantees the request will not be queued or no longer be re-queued (or otherwise used). However, with the current implementation it doesn't make sure that the request in ep0 isn't reused. Fix this by dequeuing the ep0req on functionfs_unbind before freeing the request to align with the definition. Fixes: ddf8abd25994 ("USB: f_fs: the FunctionFS driver") Signed-off-by: Udipto Goswami Tested-by: Krishna Kurapati Link: https://lore.kernel.org/r/20221215052906.8993-3-quic_ugoswami@quicinc.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin

usb: gadget: f_fs: Prevent race during ffs_ep0_queue_wait

2023-02-01T07:27:11+00:00

[ Upstream commit 6a19da111057f69214b97c62fb0ac59023970850 ] While performing fast composition switch, there is a possibility that the process of ffs_ep0_write/ffs_ep0_read get into a race condition due to ep0req being freed up from functionfs_unbind. Consider the scenario that the ffs_ep0_write calls the ffs_ep0_queue_wait by taking a lock &ffs->ev.waitq.lock. However, the functionfs_unbind isn't bounded so it can go ahead and mark the ep0req to NULL, and since there is no NULL check in ffs_ep0_queue_wait we will end up in use-after-free. Fix this by making a serialized execution between the two functions using a mutex_lock(ffs->mutex). Fixes: ddf8abd25994 ("USB: f_fs: the FunctionFS driver") Signed-off-by: Udipto Goswami Tested-by: Krishna Kurapati Link: https://lore.kernel.org/r/20221215052906.8993-2-quic_ugoswami@quicinc.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin

usb: gadget: f_fs: change ep->ep safe in ffs_epfile_io()

2022-06-22T12:22:04+00:00

commit 0698f0209d8032e8869525aeb68f65ee7fde12ad upstream. In ffs_epfile_io(), when read/write data in blocking mode, it will wait the completion in interruptible mode, if task receive a signal, it will terminate the wait, at same time, if function unbind occurs, ffs_func_unbind() will kfree all eps, ffs_epfile_io() still try to dequeue request by dereferencing ep which may become invalid. Fix it by add ep spinlock and will not dereference ep if it is not valid. Cc: # 5.15 Reported-by: Michael Wu Tested-by: Michael Wu Reviewed-by: John Keeping Signed-off-by: Linyu Yuan Link: https://lore.kernel.org/r/1654863478-26228-3-git-send-email-quic_linyyuan@quicinc.com Signed-off-by: Greg Kroah-Hartman