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Subject[PATCH] hid: hid-lg4ff: fix possible sleep-in-atomic-context bug
Date
The driver may sleep while holding a read lock.
The function call path (from bottom to top) in Linux 4.19 is:

drivers/hid/hid-core.c, 1459:
hid_alloc_report_buf(GFP_KERNEL) in __hid_request
./include/linux/hid.h, 1051:
__hid_request in hid_hw_request
drivers/hid/hid-lg4ff.c, 538:
hid_hw_request in lg4ff_set_autocenter_default
drivers/hid/hid-lg4ff.c, 497:
_raw_spin_lock_irqsave in lg4ff_set_autocenter_default

drivers/hid/hid-core.c, 1459:
hid_alloc_report_buf(GFP_KERNEL) in __hid_request
./include/linux/hid.h, 1051:
__hid_request in hid_hw_request
drivers/hid/hid-lg4ff.c, 585:
hid_hw_request in lg4ff_set_autocenter_ffex
drivers/hid/hid-lg4ff.c, 576:
_raw_spin_lock_irqsave in lg4ff_set_autocenter_ffex

drivers/hid/hid-core.c, 1459:
hid_alloc_report_buf(GFP_KERNEL) in __hid_request
./include/linux/hid.h, 1051:
__hid_request in hid_hw_request
drivers/hid/hid-lg4ff.c, 1116:
hid_hw_request in lg4ff_set_leds
drivers/hid/hid-lg4ff.c, 1108:
_raw_spin_lock_irqsave in lg4ff_set_leds

drivers/hid/hid-core.c, 1459:
hid_alloc_report_buf(GFP_KERNEL) in __hid_request
./include/linux/hid.h, 1051:
__hid_request in hid_hw_request
drivers/hid/hid-lg4ff.c, 465:
hid_hw_request in lg4ff_play
drivers/hid/hid-lg4ff.c, 441:
_raw_spin_lock_irqsave in lg4ff_play

drivers/hid/hid-core.c, 1459:
hid_alloc_report_buf(GFP_KERNEL) in __hid_request
./include/linux/hid.h, 1051:
__hid_request in hid_hw_request
drivers/hid/hid-lg4ff.c, 664:
hid_hw_request in lg4ff_set_range_dfp
drivers/hid/hid-lg4ff.c, 648:
_raw_spin_lock_irqsave in lg4ff_set_range_dfp

drivers/hid/hid-core.c, 1459:
hid_alloc_report_buf(GFP_KERNEL) in __hid_request
./include/linux/hid.h, 1051:
__hid_request in hid_hw_request
drivers/hid/hid-lg4ff.c, 620:
hid_hw_request in lg4ff_set_range_g25
drivers/hid/hid-lg4ff.c, 611:
_raw_spin_lock_irqsave in lg4ff_set_range_g25

hid_alloc_report_buf(GFP_KERNEL) can sleep at runtime.

To fix these bugs, hid_hw_request() is called without holding the
spinlock.

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

Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
---
drivers/hid/hid-lg4ff.c | 22 +++++++++++++---------
1 file changed, 13 insertions(+), 9 deletions(-)

diff --git a/drivers/hid/hid-lg4ff.c b/drivers/hid/hid-lg4ff.c
index 5e6a0cef2a06..047a19da3aed 100644
--- a/drivers/hid/hid-lg4ff.c
+++ b/drivers/hid/hid-lg4ff.c
@@ -443,8 +443,8 @@ static int lg4ff_play(struct input_dev *dev, void *data, struct ff_effect *effec
value[5] = 0x00;
value[6] = 0x00;

- hid_hw_request(hid, entry->report, HID_REQ_SET_REPORT);
spin_unlock_irqrestore(&entry->report_lock, flags);
+ hid_hw_request(hid, entry->report, HID_REQ_SET_REPORT);
return 0;
}

@@ -456,8 +456,8 @@ static int lg4ff_play(struct input_dev *dev, void *data, struct ff_effect *effec
value[5] = 0x00;
value[6] = 0x00;

- hid_hw_request(hid, entry->report, HID_REQ_SET_REPORT);
spin_unlock_irqrestore(&entry->report_lock, flags);
+ hid_hw_request(hid, entry->report, HID_REQ_SET_REPORT);
break;
}
return 0;
@@ -498,8 +498,8 @@ static void lg4ff_set_autocenter_default(struct input_dev *dev, u16 magnitude)
value[5] = 0x00;
value[6] = 0x00;

- hid_hw_request(hid, entry->report, HID_REQ_SET_REPORT);
spin_unlock_irqrestore(&entry->report_lock, flags);
+ hid_hw_request(hid, entry->report, HID_REQ_SET_REPORT);
return;
}

@@ -529,7 +529,9 @@ static void lg4ff_set_autocenter_default(struct input_dev *dev, u16 magnitude)
value[5] = 0x00;
value[6] = 0x00;

+ spin_unlock_irqrestore(&entry->report_lock, flags);
hid_hw_request(hid, entry->report, HID_REQ_SET_REPORT);
+ spin_lock_irqsave(&entry->report_lock, flags);

/* Activate Auto-Center */
value[0] = 0x14;
@@ -540,8 +542,8 @@ static void lg4ff_set_autocenter_default(struct input_dev *dev, u16 magnitude)
value[5] = 0x00;
value[6] = 0x00;

- hid_hw_request(hid, entry->report, HID_REQ_SET_REPORT);
spin_unlock_irqrestore(&entry->report_lock, flags);
+ hid_hw_request(hid, entry->report, HID_REQ_SET_REPORT);
}

/* Sends autocentering command compatible with Formula Force EX */
@@ -576,8 +578,8 @@ static void lg4ff_set_autocenter_ffex(struct input_dev *dev, u16 magnitude)
value[5] = 0x00;
value[6] = 0x00;

- hid_hw_request(hid, entry->report, HID_REQ_SET_REPORT);
spin_unlock_irqrestore(&entry->report_lock, flags);
+ hid_hw_request(hid, entry->report, HID_REQ_SET_REPORT);
}

/* Sends command to set range compatible with G25/G27/Driving Force GT */
@@ -611,8 +613,8 @@ static void lg4ff_set_range_g25(struct hid_device *hid, u16 range)
value[5] = 0x00;
value[6] = 0x00;

- hid_hw_request(hid, entry->report, HID_REQ_SET_REPORT);
spin_unlock_irqrestore(&entry->report_lock, flags);
+ hid_hw_request(hid, entry->report, HID_REQ_SET_REPORT);
}

/* Sends commands to set range compatible with Driving Force Pro wheel */
@@ -655,7 +657,9 @@ static void lg4ff_set_range_dfp(struct hid_device *hid, u16 range)
value[1] = 0x02;
full_range = 200;
}
+ spin_unlock_irqrestore(&entry->report_lock, flags);
hid_hw_request(hid, entry->report, HID_REQ_SET_REPORT);
+ spin_lock_irqsave(&entry->report_lock, flags);

/* Prepare "fine" limit command */
value[0] = 0x81;
@@ -667,8 +671,8 @@ static void lg4ff_set_range_dfp(struct hid_device *hid, u16 range)
value[6] = 0x00;

if (range == 200 || range == 900) { /* Do not apply any fine limit */
- hid_hw_request(hid, entry->report, HID_REQ_SET_REPORT);
spin_unlock_irqrestore(&entry->report_lock, flags);
+ hid_hw_request(hid, entry->report, HID_REQ_SET_REPORT);
return;
}

@@ -682,8 +686,8 @@ static void lg4ff_set_range_dfp(struct hid_device *hid, u16 range)
value[5] = (start_right & 0xe) << 4 | (start_left & 0xe);
value[6] = 0xff;

- hid_hw_request(hid, entry->report, HID_REQ_SET_REPORT);
spin_unlock_irqrestore(&entry->report_lock, flags);
+ hid_hw_request(hid, entry->report, HID_REQ_SET_REPORT);
}

static const struct lg4ff_compat_mode_switch *lg4ff_get_mode_switch_command(const u16 real_product_id, const u16 target_product_id)
@@ -1107,8 +1111,8 @@ static void lg4ff_set_leds(struct hid_device *hid, u8 leds)
value[4] = 0x00;
value[5] = 0x00;
value[6] = 0x00;
- hid_hw_request(hid, entry->report, HID_REQ_SET_REPORT);
spin_unlock_irqrestore(&entry->report_lock, flags);
+ hid_hw_request(hid, entry->report, HID_REQ_SET_REPORT);
}

static void lg4ff_led_set_brightness(struct led_classdev *led_cdev,
--
2.17.1
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