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Message-Id: <20210614102701.455627186@linuxfoundation.org>
Date: Mon, 14 Jun 2021 12:27:11 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, Wesley Cheng <wcheng@...eaurora.org>
Subject: [PATCH 5.12 099/173] usb: gadget: f_fs: Ensure io_completion_wq is idle during unbind
From: Wesley Cheng <wcheng@...eaurora.org>
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@...eaurora.org>
Cc: stable <stable@...r.kernel.org>
Link: https://lore.kernel.org/r/1621644261-1236-1-git-send-email-wcheng@codeaurora.org
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
drivers/usb/gadget/function/f_fs.c | 3 +++
1 file changed, 3 insertions(+)
--- a/drivers/usb/gadget/function/f_fs.c
+++ b/drivers/usb/gadget/function/f_fs.c
@@ -3567,6 +3567,9 @@ static void ffs_func_unbind(struct usb_c
ffs->func = NULL;
}
+ /* Drain any pending AIO completions */
+ drain_workqueue(ffs->io_completion_wq);
+
if (!--opts->refcnt)
functionfs_unbind(ffs);
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