diff options
| author | Sven Peter <sven@svenpeter.dev> | 2022-11-28 17:15:26 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-11-29 13:27:49 +0100 |
| commit | 62c73bfea048e66168df09da6d3e4510ecda40bb (patch) | |
| tree | c96b0eed8ab7bf22a81db38809f139ff3e6e9485 /drivers/usb | |
| parent | 4051a1c96e4883f3445cc8f239c214be622f4c6c (diff) | |
usb: dwc3: Fix race between dwc3_set_mode and __dwc3_set_mode
dwc->desired_dr_role is changed by dwc3_set_mode inside a spinlock but
then read by __dwc3_set_mode outside of that lock. This can lead to a
race condition when very quick successive role switch events happen:
CPU A
dwc3_set_mode(DWC3_GCTL_PRTCAP_HOST) // first role switch event
spin_lock_irqsave(&dwc->lock, flags);
dwc->desired_dr_role = mode; // DWC3_GCTL_PRTCAP_HOST
spin_unlock_irqrestore(&dwc->lock, flags);
queue_work(system_freezable_wq, &dwc->drd_work);
CPU B
__dwc3_set_mode
// ....
spin_lock_irqsave(&dwc->lock, flags);
// desired_dr_role is DWC3_GCTL_PRTCAP_HOST
dwc3_set_prtcap(dwc, dwc->desired_dr_role);
spin_unlock_irqrestore(&dwc->lock, flags);
CPU A
dwc3_set_mode(DWC3_GCTL_PRTCAP_DEVICE) // second event
spin_lock_irqsave(&dwc->lock, flags);
dwc->desired_dr_role = mode; // DWC3_GCTL_PRTCAP_DEVICE
spin_unlock_irqrestore(&dwc->lock, flags);
CPU B (continues running __dwc3_set_mode)
switch (dwc->desired_dr_role) { // DWC3_GCTL_PRTCAP_DEVICE
// ....
case DWC3_GCTL_PRTCAP_DEVICE:
// ....
ret = dwc3_gadget_init(dwc);
We then have DWC3_GCTL.DWC3_GCTL_PRTCAPDIR = DWC3_GCTL_PRTCAP_HOST and
dwc->current_dr_role = DWC3_GCTL_PRTCAP_HOST but initialized the
controller in device mode. It's also possible to get into a state
where both host and device are intialized at the same time.
Fix this race by creating a local copy of desired_dr_role inside
__dwc3_set_mode while holding dwc->lock.
Fixes: 41ce1456e1db ("usb: dwc3: core: make dwc3_set_mode() work properly")
Cc: stable <stable@kernel.org>
Acked-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Signed-off-by: Sven Peter <sven@svenpeter.dev>
Link: https://lore.kernel.org/r/20221128161526.79730-1-sven@svenpeter.dev
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/usb')
| -rw-r--r-- | drivers/usb/dwc3/core.c | 16 |
1 files changed, 10 insertions, 6 deletions
diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c index 1f348bc867c2..fc38a8b13efa 100644 --- a/drivers/usb/dwc3/core.c +++ b/drivers/usb/dwc3/core.c @@ -122,21 +122,25 @@ static void __dwc3_set_mode(struct work_struct *work) unsigned long flags; int ret; u32 reg; + u32 desired_dr_role; mutex_lock(&dwc->mutex); + spin_lock_irqsave(&dwc->lock, flags); + desired_dr_role = dwc->desired_dr_role; + spin_unlock_irqrestore(&dwc->lock, flags); pm_runtime_get_sync(dwc->dev); if (dwc->current_dr_role == DWC3_GCTL_PRTCAP_OTG) dwc3_otg_update(dwc, 0); - if (!dwc->desired_dr_role) + if (!desired_dr_role) goto out; - if (dwc->desired_dr_role == dwc->current_dr_role) + if (desired_dr_role == dwc->current_dr_role) goto out; - if (dwc->desired_dr_role == DWC3_GCTL_PRTCAP_OTG && dwc->edev) + if (desired_dr_role == DWC3_GCTL_PRTCAP_OTG && dwc->edev) goto out; switch (dwc->current_dr_role) { @@ -164,7 +168,7 @@ static void __dwc3_set_mode(struct work_struct *work) */ if (dwc->current_dr_role && ((DWC3_IP_IS(DWC3) || DWC3_VER_IS_PRIOR(DWC31, 190A)) && - dwc->desired_dr_role != DWC3_GCTL_PRTCAP_OTG)) { + desired_dr_role != DWC3_GCTL_PRTCAP_OTG)) { reg = dwc3_readl(dwc->regs, DWC3_GCTL); reg |= DWC3_GCTL_CORESOFTRESET; dwc3_writel(dwc->regs, DWC3_GCTL, reg); @@ -184,11 +188,11 @@ static void __dwc3_set_mode(struct work_struct *work) spin_lock_irqsave(&dwc->lock, flags); - dwc3_set_prtcap(dwc, dwc->desired_dr_role); + dwc3_set_prtcap(dwc, desired_dr_role); spin_unlock_irqrestore(&dwc->lock, flags); - switch (dwc->desired_dr_role) { + switch (desired_dr_role) { case DWC3_GCTL_PRTCAP_HOST: ret = dwc3_host_init(dwc); if (ret) { |