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usb: gadget: f_fs: Ensure io_completion_wq is idle during unbind

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commit 6fc1db5e6211e30fbb1cee8d7925d79d4ed2ae14 upstream.

During unbind, ffs_func_eps_disable() will be executed, resulting in
completion callbacks for any pending USB requests.  When using AIO,
irrespective of the completion status, io_data work is queued to
io_completion_wq to evaluate and handle the completed requests.  Since
work runs asynchronously to the unbind() routine, there can be a
scenario where the work runs after the USB gadget has been fully
removed, resulting in accessing of a resource which has been already
freed. (i.e. usb_ep_free_request() accessing the USB ep structure)

Explicitly drain the io_completion_wq, instead of relying on the
destroy_workqueue() (in ffs_data_put()) to make sure no pending
completion work items are running.

Signed-off-by: Wesley Cheng <wcheng@codeaurora.org>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/1621644261-1236-1-git-send-email-wcheng@codeaurora.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Wesley Cheng
2021-05-21 17:44:21 -07:00
committed by Greg Kroah-Hartman
parent 0b3bb7950e
commit 5cead89696
1 changed files with 3 additions and 0 deletions
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3
drivers/usb/gadget/function/f_fs.c
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@@ -3566,6 +3566,9 @@ static void ffs_func_unbind(struct usb_configuration *c,
ffs->func = NULL; ffs->func = NULL;
} }
/* Drain any pending AIO completions */
drain_workqueue(ffs->io_completion_wq);
if (!--opts->refcnt) if (!--opts->refcnt)
functionfs_unbind(ffs); functionfs_unbind(ffs);