linux-kernel - [PATCH 5.4 163/270] usb: dwc2: Fix error path in gadget registration

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Date:   Mon, 17 Aug 2020 17:16:04 +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, Minas Harutyunyan <hminas@...opsys.com>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Felipe Balbi <balbi@...nel.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.4 163/270] usb: dwc2: Fix error path in gadget registration

From: Marek Szyprowski <m.szyprowski@...sung.com>

[ Upstream commit 33a06f1300a79cfd461cea0268f05e969d4f34ec ]

When gadget registration fails, one should not call usb_del_gadget_udc().
Ensure this by setting gadget->udc to NULL. Also in case of a failure
there is no need to disable low-level hardware, so return immiedetly
instead of jumping to error_init label.

This fixes the following kernel NULL ptr dereference on gadget failure
(can be easily triggered with g_mass_storage without any module
parameters):

dwc2 12480000.hsotg: dwc2_check_params: Invalid parameter besl=1
dwc2 12480000.hsotg: dwc2_check_params: Invalid parameter g_np_tx_fifo_size=1024
dwc2 12480000.hsotg: EPs: 16, dedicated fifos, 7808 entries in SPRAM
Mass Storage Function, version: 2009/09/11
LUN: removable file: (no medium)
no file given for LUN0
g_mass_storage 12480000.hsotg: failed to start g_mass_storage: -22
8<--- cut here ---
Unable to handle kernel NULL pointer dereference at virtual address 00000104
pgd = (ptrval)
[00000104] *pgd=00000000
Internal error: Oops: 805 [#1] PREEMPT SMP ARM
Modules linked in:
CPU: 0 PID: 12 Comm: kworker/0:1 Not tainted 5.8.0-rc5 #3133
Hardware name: Samsung Exynos (Flattened Device Tree)
Workqueue: events deferred_probe_work_func
PC is at usb_del_gadget_udc+0x38/0xc4
LR is at __mutex_lock+0x31c/0xb18
...
Process kworker/0:1 (pid: 12, stack limit = 0x(ptrval))
Stack: (0xef121db0 to 0xef122000)
...
[<c076bf3c>] (usb_del_gadget_udc) from [<c0726bec>] (dwc2_hsotg_remove+0x10/0x20)
[<c0726bec>] (dwc2_hsotg_remove) from [<c0711208>] (dwc2_driver_probe+0x57c/0x69c)
[<c0711208>] (dwc2_driver_probe) from [<c06247c0>] (platform_drv_probe+0x6c/0xa4)
[<c06247c0>] (platform_drv_probe) from [<c0621df4>] (really_probe+0x200/0x48c)
[<c0621df4>] (really_probe) from [<c06221e8>] (driver_probe_device+0x78/0x1fc)
[<c06221e8>] (driver_probe_device) from [<c061fcd4>] (bus_for_each_drv+0x74/0xb8)
[<c061fcd4>] (bus_for_each_drv) from [<c0621b54>] (__device_attach+0xd4/0x16c)
[<c0621b54>] (__device_attach) from [<c0620c98>] (bus_probe_device+0x88/0x90)
[<c0620c98>] (bus_probe_device) from [<c06211b0>] (deferred_probe_work_func+0x3c/0xd0)
[<c06211b0>] (deferred_probe_work_func) from [<c0149280>] (process_one_work+0x234/0x7dc)
[<c0149280>] (process_one_work) from [<c014986c>] (worker_thread+0x44/0x51c)
[<c014986c>] (worker_thread) from [<c0150b1c>] (kthread+0x158/0x1a0)
[<c0150b1c>] (kthread) from [<c0100114>] (ret_from_fork+0x14/0x20)
Exception stack(0xef121fb0 to 0xef121ff8)
...
---[ end trace 9724c2fc7cc9c982 ]---

While fixing this also fix the double call to dwc2_lowlevel_hw_disable()
if dr_mode is set to USB_DR_MODE_PERIPHERAL. In such case low-level
hardware is already disabled before calling usb_add_gadget_udc(). That
function correctly preserves low-level hardware state, there is no need
for the second unconditional dwc2_lowlevel_hw_disable() call.

Fixes: 207324a321a8 ("usb: dwc2: Postponed gadget registration to the udc class driver")
Acked-by: Minas Harutyunyan <hminas@...opsys.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@...sung.com>
Signed-off-by: Felipe Balbi <balbi@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/usb/dwc2/platform.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/dwc2/platform.c b/drivers/usb/dwc2/platform.c
index 4e14c4f7fed7a..34bb6124f1e2f 100644
--- a/drivers/usb/dwc2/platform.c
+++ b/drivers/usb/dwc2/platform.c
@@ -514,6 +514,7 @@ static int dwc2_driver_probe(struct platform_device *dev)
 	if (hsotg->gadget_enabled) {
 		retval = usb_add_gadget_udc(hsotg->dev, &hsotg->gadget);
 		if (retval) {
+			hsotg->gadget.udc = NULL;
 			dwc2_hsotg_remove(hsotg);
 			goto error;
 		}
@@ -522,7 +523,8 @@ static int dwc2_driver_probe(struct platform_device *dev)
 	return 0;
 
 error:
-	dwc2_lowlevel_hw_disable(hsotg);
+	if (hsotg->dr_mode != USB_DR_MODE_PERIPHERAL)
+		dwc2_lowlevel_hw_disable(hsotg);
 	return retval;
 }
 
-- 
2.25.1