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    Subject[PATCH 4.14 114/228] usb: dwc2: Fix error path in gadget registration
    Date
    From: Marek Szyprowski <m.szyprowski@samsung.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@synopsys.com>
    Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
    Signed-off-by: Felipe Balbi <balbi@kernel.org>
    Signed-off-by: Sasha Levin <sashal@kernel.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 442cb93935dd4..405dccf92a315 100644
    --- a/drivers/usb/dwc2/platform.c
    +++ b/drivers/usb/dwc2/platform.c
    @@ -459,6 +459,7 @@ 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;
    }
    @@ -467,7 +468,8 @@ 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


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