iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

usb: dwc3: Fix race between dwc3_set_mode and __dwc3_set_mode

Browse Source 
commit 62c73bfea048e66168df09da6d3e4510ecda40bb upstream.

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>
This commit is contained in:
Sven Peter 2022-11-28 17:15:26 +01:00 committed by Greg Kroah-Hartman
parent 0e883f3bc8
commit e6bf6c4022
1 changed files with 10 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
drivers/usb/dwc3/core.c
View File

@ -120,21 +120,25 @@ 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) {
@ -162,7 +166,7 @@ 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);
@ -182,11 +186,11 @@ 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) {