[SRU][N][PATCH 1/1] HID: i2c-hid: remove I2C_HID_READ_PENDING flag to prevent lock-up
Bethany Jamison
bethany.jamison at canonical.com
Tue Jun 25 17:46:07 UTC 2024
From: Nam Cao <namcao at linutronix.de>
commit 9c0f59e47a90c54d0153f8ddc0f80d7a36207d0e upstream.
The flag I2C_HID_READ_PENDING is used to serialize I2C operations.
However, this is not necessary, because I2C core already has its own
locking for that.
More importantly, this flag can cause a lock-up: if the flag is set in
i2c_hid_xfer() and an interrupt happens, the interrupt handler
(i2c_hid_irq) will check this flag and return immediately without doing
anything, then the interrupt handler will be invoked again in an
infinite loop.
Since interrupt handler is an RT task, it takes over the CPU and the
flag-clearing task never gets scheduled, thus we have a lock-up.
Delete this unnecessary flag.
Reported-and-tested-by: Eva Kurchatova <nyandarknessgirl at gmail.com>
Closes: https://lore.kernel.org/r/CA+eeCSPUDpUg76ZO8dszSbAGn+UHjcyv8F1J-CUPVARAzEtW9w@mail.gmail.com
Fixes: 4a200c3b9a40 ("HID: i2c-hid: introduce HID over i2c specification implementation")
Cc: <stable at vger.kernel.org>
Signed-off-by: Nam Cao <namcao at linutronix.de>
Signed-off-by: Jiri Kosina <jkosina at suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
(cherry picked from commit 418c5575d56410c6e186ab727bf32ae32447d497 linux-6.8.y)
CVE-2024-35997
Signed-off-by: Bethany Jamison <bethany.jamison at canonical.com>
---
drivers/hid/i2c-hid/i2c-hid-core.c | 9 ---------
1 file changed, 9 deletions(-)
diff --git a/drivers/hid/i2c-hid/i2c-hid-core.c b/drivers/hid/i2c-hid/i2c-hid-core.c
index 13d67d7c67b46..d965382196c69 100644
--- a/drivers/hid/i2c-hid/i2c-hid-core.c
+++ b/drivers/hid/i2c-hid/i2c-hid-core.c
@@ -64,7 +64,6 @@
/* flags */
#define I2C_HID_STARTED 0
#define I2C_HID_RESET_PENDING 1
-#define I2C_HID_READ_PENDING 2
#define I2C_HID_PWR_ON 0x00
#define I2C_HID_PWR_SLEEP 0x01
@@ -190,15 +189,10 @@ static int i2c_hid_xfer(struct i2c_hid *ihid,
msgs[n].len = recv_len;
msgs[n].buf = recv_buf;
n++;
-
- set_bit(I2C_HID_READ_PENDING, &ihid->flags);
}
ret = i2c_transfer(client->adapter, msgs, n);
- if (recv_len)
- clear_bit(I2C_HID_READ_PENDING, &ihid->flags);
-
if (ret != n)
return ret < 0 ? ret : -EIO;
@@ -556,9 +550,6 @@ static irqreturn_t i2c_hid_irq(int irq, void *dev_id)
{
struct i2c_hid *ihid = dev_id;
- if (test_bit(I2C_HID_READ_PENDING, &ihid->flags))
- return IRQ_HANDLED;
-
i2c_hid_get_input(ihid);
return IRQ_HANDLED;
--
2.34.1
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