[PATCH v2] btusb: fix wrong use of PTR_ERR()

From: Adam Lee
Date: Tue Jul 09 2013 - 04:48:26 EST


PTR_ERR() returns a signed long type value which is limited by IS_ERR(),
it must be a negative number and bigger than -MAX_ERRNO(-4095).

The bug here, btusb_setup_intel_patching()'s return value might come
from -PTR_ERR() which must be a positive number, we can't judge if it's
an error by "if (ret < 0)", the wrong use here leads to failure as
below, even panic.

Error log:

[ 12.958920] Bluetooth: hci0 command 0xfc8e tx timeout
[ 14.961765] Bluetooth: hci0 command 0xfc8e tx timeout
[ 16.964688] Bluetooth: hci0 command 0xfc8e tx timeout
[ 20.954501] Bluetooth: hci0 sending Intel patch command (0xfc8e) failed (-110)
[ 22.957358] Bluetooth: hci0 command 0xfc8e tx timeout
[ 30.948922] Bluetooth: hci0 sending Intel patch command (0xfc8e) failed (-110)
[ 32.951780] Bluetooth: hci0 command 0xfc8e tx timeout
[ 40.943359] Bluetooth: hci0 sending Intel patch command (0xfc8e) failed (-110)
[ 42.946219] Bluetooth: hci0 command 0xfc8e tx timeout
[ 50.937812] Bluetooth: hci0 sending Intel patch command (0xfc8e) failed (-110)
[ 52.940670] Bluetooth: hci0 command 0xfc8e tx timeout
[ 60.932236] Bluetooth: hci0 sending Intel patch command (0xfc8e) failed (-110)
[ 62.935092] Bluetooth: hci0 command 0xfc8e tx timeout
[ 70.926688] Bluetooth: hci0 sending Intel patch command (0xfc8e) failed (-110)
[ 72.929545] Bluetooth: hci0 command 0xfc8e tx timeout
[ 80.921111] Bluetooth: hci0 sending Intel patch command (0xfc8e) failed (-110)
[ 82.923969] Bluetooth: hci0 command 0xfc2f tx timeout
[ 90.915542] Bluetooth: hci0 sending Intel patch command (0xfc2f) failed (-110)
[ 92.918406] Bluetooth: hci0 command 0xfc11 tx timeout
[ 100.909955] Bluetooth: hci0 sending Intel patch command (0xfc11) failed (-110)
[ 102.912858] Bluetooth: hci0 command 0xfc60 tx timeout
[ 110.904394] Bluetooth: hci0 sending Intel patch command (0xfc60) failed (-110)
[ 112.907293] Bluetooth: hci0 command 0xfc11 tx timeout
[ 120.898831] Bluetooth: hci0 exiting Intel manufacturer mode failed (-110)
[ 120.904757] bluetoothd[1030]: segfault at 4 ip 00007f8b2eb55236 sp 00007fff53ff6920 error 4 in bluetoothd[7f8b2eaff000+cb000]

Signed-off-by: Adam Lee <adam.lee@xxxxxxxxxxxxx>
---
drivers/bluetooth/btusb.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
index 7a7e5f8..05a38a2 100644
--- a/drivers/bluetooth/btusb.c
+++ b/drivers/bluetooth/btusb.c
@@ -1256,7 +1256,7 @@ static int btusb_setup_intel(struct hci_dev *hdev)

ret = btusb_setup_intel_patching(hdev, fw, &fw_ptr,
&disable_patch);
- if (ret < 0)
+ if (!ret)
goto exit_mfg_deactivate;
}

--
1.8.3.2
#include <stdio.h>

#define MAX_ERRNO 4095

#define IS_ERR_VALUE(x) ((x) >= (unsigned long)-MAX_ERRNO)

static inline long IS_ERR(const void *ptr)
{
return IS_ERR_VALUE((unsigned long)ptr);
}

static inline long PTR_ERR(const void *ptr)
{
return (long) ptr;
}

int main(int argc, const char *argv[])
{
void *ptr = (void *)-1;

printf("ptr = %p, -PTR_ERR(ptr) = %ld\n\n", ptr, -PTR_ERR(ptr));

if(IS_ERR(ptr)) {
if (-PTR_ERR(ptr) < 0)
printf("That's what the codes want.\n");
else
printf("Bug happens!\n");
}

return 0;
}