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zcrypt: fix possible race when unloading zcrypt driver modules

S390 Martin Schwidefsky 1 participant 1 message Mar 19, 2007

Subsystems (2)
s390 s390 zcrypt and pkey driver and AP bus
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Martin Schwidefsky

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From: Ralph Wuerthner <[email protected]>

[S390] zcrypt: fix possible race when unloading zcrypt driver modules

Move try_module_get() call into spin protected block to prevent zcrypt driver module unload while submitting a request to driver.

Signed-off-by Ralph Wuerthner <[email protected]>
Signed-off-by Martin Schwidefsky <[email protected]>

---

 drivers/s390/crypto/zcrypt_api.c |   12 ++++++------
 1 files changed, 6 insertions(+), 6 deletions(-)
drivers/s390/crypto/zcrypt_api.c +6 -6
diff -urpN linux-2.6/drivers/s390/crypto/zcrypt_api.c linux-2.6-patched/drivers/s390/crypto/zcrypt_api.c
@@ -298,14 +298,14 @@ static long zcrypt_rsa_modexpo(struct ic
 		get_device(&zdev->ap_dev->device);
 		zdev->request_count++;
 		__zcrypt_decrease_preference(zdev);
-		spin_unlock_bh(&zcrypt_device_lock);
 		if (try_module_get(zdev->ap_dev->drv->driver.owner)) {
+			spin_unlock_bh(&zcrypt_device_lock);
 			rc = zdev->ops->rsa_modexpo(zdev, mex);
+			spin_lock_bh(&zcrypt_device_lock);
 			module_put(zdev->ap_dev->drv->driver.owner);
 		}
 		else
 			rc = -EAGAIN;
-		spin_lock_bh(&zcrypt_device_lock);
 		zdev->request_count--;
 		__zcrypt_increase_preference(zdev);
 		put_device(&zdev->ap_dev->device);

@@ -373,14 +373,14 @@ static long zcrypt_rsa_crt(struct ica_rs
 		get_device(&zdev->ap_dev->device);
 		zdev->request_count++;
 		__zcrypt_decrease_preference(zdev);
-		spin_unlock_bh(&zcrypt_device_lock);
 		if (try_module_get(zdev->ap_dev->drv->driver.owner)) {
+			spin_unlock_bh(&zcrypt_device_lock);
 			rc = zdev->ops->rsa_modexpo_crt(zdev, crt);
+			spin_lock_bh(&zcrypt_device_lock);
 			module_put(zdev->ap_dev->drv->driver.owner);
 		}
 		else
 			rc = -EAGAIN;
-		spin_lock_bh(&zcrypt_device_lock);
 		zdev->request_count--;
 		__zcrypt_increase_preference(zdev);
 		put_device(&zdev->ap_dev->device);

@@ -408,14 +408,14 @@ static long zcrypt_send_cprb(struct ica_
 		get_device(&zdev->ap_dev->device);
 		zdev->request_count++;
 		__zcrypt_decrease_preference(zdev);
-		spin_unlock_bh(&zcrypt_device_lock);
 		if (try_module_get(zdev->ap_dev->drv->driver.owner)) {
+			spin_unlock_bh(&zcrypt_device_lock);
 			rc = zdev->ops->send_cprb(zdev, xcRB);
+			spin_lock_bh(&zcrypt_device_lock);
 			module_put(zdev->ap_dev->drv->driver.owner);
 		}
 		else
 			rc = -EAGAIN;
-		spin_lock_bh(&zcrypt_device_lock);
 		zdev->request_count--;
 		__zcrypt_increase_preference(zdev);
 		put_device(&zdev->ap_dev->device);