From: Johan Hovold johan@kernel.org
stable inclusion from stable-5.10.73 commit fc8b3e838bdf343e3341df176fa7d8170ea5c691 bugzilla: 182983 https://gitee.com/openeuler/kernel/issues/I4I3M0
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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commit 65a205e6113506e69a503b61d97efec43fc10fd7 upstream.
A recent change that started reporting break events to the line discipline caused the tty-buffer insertions to no longer be serialised by inserting events also from the completion handler for the interrupt endpoint.
Completion calls for distinct endpoints are not guaranteed to be serialised. For example, in case a host-controller driver uses bottom-half completion, the interrupt and bulk-in completion handlers can end up running in parallel on two CPUs (high-and low-prio tasklets, respectively) thereby breaking the tty layer's single producer assumption.
Fix this by holding the read lock also when inserting characters from the bulk endpoint.
Fixes: 08dff274edda ("cdc-acm: fix BREAK rx code path adding necessary calls") Cc: stable@vger.kernel.org Acked-by: Oliver Neukum oneukum@suse.com Signed-off-by: Johan Hovold johan@kernel.org Link: https://lore.kernel.org/r/20210929090937.7410-2-johan@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Chen Jun chenjun102@huawei.com Acked-by: Weilong Chen chenweilong@huawei.com
Signed-off-by: Chen Jun chenjun102@huawei.com --- drivers/usb/class/cdc-acm.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c index 7748b1335558..80508daf75ac 100644 --- a/drivers/usb/class/cdc-acm.c +++ b/drivers/usb/class/cdc-acm.c @@ -475,11 +475,16 @@ static int acm_submit_read_urbs(struct acm *acm, gfp_t mem_flags)
static void acm_process_read_urb(struct acm *acm, struct urb *urb) { + unsigned long flags; + if (!urb->actual_length) return;
+ spin_lock_irqsave(&acm->read_lock, flags); tty_insert_flip_string(&acm->port, urb->transfer_buffer, urb->actual_length); + spin_unlock_irqrestore(&acm->read_lock, flags); + tty_flip_buffer_push(&acm->port); }