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Wesley Cheng 73c05ad46b usb: gadget: f_fs: Fix race between aio_cancel() and AIO request complete 
commit 24729b307e upstream.

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 b566d38857 ("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 b566d38857 ("usb: gadget: f_fs: use io_data->status
  consistently")

Fixes: 2e4c7553cd ("usb: gadget: f_fs: add aio support")
Cc: stable <stable@kernel.org>	# b566d38857 ("usb: gadget: f_fs: use io_data->status consistently")
Signed-off-by: Wesley Cheng <quic_wcheng@quicinc.com>
Link: https://lore.kernel.org/r/20240409014059.6740-1-quic_wcheng@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2024-05-17 12:02:28 +02:00
arch ARM: 9381/1: kasan: clear stale stack poison 2024-05-17 12:02:20 +02:00
block blk-iocost: do not WARN if iocg was already offlined 2024-05-17 12:02:20 +02:00
certs certs: Reference revocation list for all keyrings 2023-08-17 20:12:41 +00:00
crypto crypto: jitter - fix CRYPTO_JITTERENTROPY help text 2024-03-26 18:19:52 -04:00
Documentation dt-bindings: net: mediatek: remove wrongly added clocks and SerDes 2024-05-17 12:02:23 +02:00
drivers usb: gadget: f_fs: Fix race between aio_cancel() and AIO request complete 2024-05-17 12:02:28 +02:00
fs btrfs: fix kvcalloc() arguments order in btrfs_ioctl_send() 2024-05-17 12:02:27 +02:00
include Reapply "drm/qxl: simplify qxl_fence_wait" 2024-05-17 12:02:27 +02:00
init rust: make mutually exclusive with CFI_CLANG 2024-05-02 16:32:42 +02:00
io_uring io_uring: Fix io_cqring_wait() not restoring sigmask on get_timespec64() failure 2024-04-27 17:11:30 +02:00
ipc Add x86 shadow stack support 2023-08-31 12:20:12 -07:00
kernel bpf: Check bloom filter map value size 2024-05-17 12:02:11 +02:00
lib Fix a potential infinite loop in extract_user_to_sg() 2024-05-17 12:02:02 +02:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm mm: turn folio_test_hugetlb into a PageType 2024-05-02 16:32:47 +02:00
net net/smc: fix neighbour and rtable leak in smc_ib_find_route() 2024-05-17 12:02:24 +02:00
rust rust: kernel: require Send for Module implementations 2024-05-17 12:01:56 +02:00
samples work around gcc bugs with 'asm goto' with outputs 2024-02-23 09:24:47 +01:00
scripts kbuild: Disable KCSAN for autogenerated *.mod.c intermediaries 2024-05-17 12:02:12 +02:00
security selinux: avoid dereference of garbage after mount failure 2024-04-10 16:35:48 +02:00
sound ALSA: line6: Zero-initialize message buffers 2024-05-17 12:02:13 +02:00
tools selftests: test_bridge_neigh_suppress.sh: Fix failures due to duplicate MAC 2024-05-17 12:02:23 +02:00
usr initramfs: Encode dependency on KBUILD_BUILD_TIMESTAMP 2023-06-06 17:54:49 +09:00
virt KVM: Always flush async #PF workqueue when vCPU is being destroyed 2024-04-03 15:28:18 +02:00
.clang-format iommu: Add for_each_group_device() 2023-05-23 08:15:51 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: rpm-pkg: rename binkernel.spec to kernel.spec 2023-07-25 00:59:33 +09:00
.mailmap 20 hotfixes. 12 are cc:stable and the remainder address post-6.5 issues 2023-10-24 09:52:16 -10:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS USB: Remove Wireless USB and UWB documentation 2023-08-09 14:17:32 +02:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS ALSA: scarlett2: Rename scarlett_gen2 to scarlett2 2024-04-27 17:11:36 +02:00
Makefile Linux 6.6.30 2024-05-02 16:32:50 +02:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.