[PATCH 5.5 066/399] usb: gadget: udc: fix possible sleep-in-atomic-context bugs in gr_probe()

Greg Kroah-Hartman
2020-02-21T07:46:20Z

From: Jia-Ju Bai <baijiaju1990@gmail.com>

[ Upstream commit 9c1ed62ae0690dfe5d5e31d8f70e70a95cb48e52 ]

The driver may sleep while holding a spinlock.
The function call path (from bottom to top) in Linux 4.19 is:

drivers/usb/gadget/udc/core.c, 1175:
kzalloc(GFP_KERNEL) in usb_add_gadget_udc_release
drivers/usb/gadget/udc/core.c, 1272:
usb_add_gadget_udc_release in usb_add_gadget_udc
drivers/usb/gadget/udc/gr_udc.c, 2186:
usb_add_gadget_udc in gr_probe
drivers/usb/gadget/udc/gr_udc.c, 2183:
spin_lock in gr_probe

drivers/usb/gadget/udc/core.c, 1195:
mutex_lock in usb_add_gadget_udc_release
drivers/usb/gadget/udc/core.c, 1272:
usb_add_gadget_udc_release in usb_add_gadget_udc
drivers/usb/gadget/udc/gr_udc.c, 2186:
usb_add_gadget_udc in gr_probe
drivers/usb/gadget/udc/gr_udc.c, 2183:
spin_lock in gr_probe

drivers/usb/gadget/udc/gr_udc.c, 212:
debugfs_create_file in gr_probe
drivers/usb/gadget/udc/gr_udc.c, 2197:
gr_dfs_create in gr_probe
drivers/usb/gadget/udc/gr_udc.c, 2183:
spin_lock in gr_probe

drivers/usb/gadget/udc/gr_udc.c, 2114:
devm_request_threaded_irq in gr_request_irq
drivers/usb/gadget/udc/gr_udc.c, 2202:
gr_request_irq in gr_probe
drivers/usb/gadget/udc/gr_udc.c, 2183:
spin_lock in gr_probe

kzalloc(GFP_KERNEL), mutex_lock(), debugfs_create_file() and
devm_request_threaded_irq() can sleep at runtime.

To fix these possible bugs, usb_add_gadget_udc(), gr_dfs_create() and
gr_request_irq() are called without handling the spinlock.

These bugs are found by a static analysis tool STCheck written by myself.

Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/usb/gadget/udc/gr_udc.c | 16 +++++++++-------
1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/drivers/usb/gadget/udc/gr_udc.c b/drivers/usb/gadget/udc/gr_udc.c
index 64d80c65bb967..aaf975c809bf9 100644
--- a/drivers/usb/gadget/udc/gr_udc.c
+++ b/drivers/usb/gadget/udc/gr_udc.c
@@ -2175,8 +2175,6 @@ static int gr_probe(struct platform_device *pdev)
return -ENOMEM;
}

- spin_lock(&dev->lock);
-
/* Inside lock so that no gadget can use this udc until probe is done */
retval = usb_add_gadget_udc(dev->dev, &dev->gadget);
if (retval) {
@@ -2185,15 +2183,21 @@ static int gr_probe(struct platform_device *pdev)
}
dev->added = 1;

+ spin_lock(&dev->lock);
+
retval = gr_udc_init(dev);
- if (retval)
+ if (retval) {
+ spin_unlock(&dev->lock);
goto out;
-
- gr_dfs_create(dev);
+ }

/* Clear all interrupt enables that might be left on since last boot */
gr_disable_interrupts_and_pullup(dev);

+ spin_unlock(&dev->lock);
+
+ gr_dfs_create(dev);
+
retval = gr_request_irq(dev, dev->irq);
if (retval) {
dev_err(dev->dev, "Failed to request irq %d\n", dev->irq);
@@ -2222,8 +2226,6 @@ static int gr_probe(struct platform_device *pdev)
dev_info(dev->dev, "regs: %p, irq %d\n", dev->regs, dev->irq);

out:
- spin_unlock(&dev->lock);
-
if (retval)
gr_remove(pdev);

--
2.20.1