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* [PATCH] phy: mdio: fix memory leak
@ 2021-09-27 11:20 Pavel Skripkin
  2021-09-27 19:17 ` Pavel Skripkin
  2021-09-28 20:39 ` [PATCH v2 1/2] Revert "net: mdiobus: Fix memory leak in __mdiobus_register" Pavel Skripkin
  0 siblings, 2 replies; 8+ messages in thread
From: Pavel Skripkin @ 2021-09-27 11:20 UTC (permalink / raw)
  To: andrew, hkallweit1, linux, davem, kuba, buytenh
  Cc: netdev, linux-kernel, Pavel Skripkin, syzbot+398e7dc692ddbbb4cfec

Syzbot reported memory leak in MDIO bus interface, the problem was in
wrong state logic.

MDIOBUS_ALLOCATED indicates 2 states:
	1. Bus is only allocated
	2. Bus allocated and __mdiobus_register() fails, but
	   device_register() was called

In case of device_register() has been called we should call put_device()
to correctly free the memory allocated for this device, but mdiobus_free()
was just calling kfree(dev) in case of MDIOBUS_ALLOCATED state

To avoid this behaviour we can add new intermediate state, which means,
that we have called device_regiter(), but failed on any of the next steps.
Clean up process for this state is the same as for MDIOBUS_UNREGISTERED,
but MDIOBUS_UNREGISTERED name does not fit to the logic described above.

Fixes: 46abc02175b3 ("phylib: give mdio buses a device tree presence")
Reported-and-tested-by: syzbot+398e7dc692ddbbb4cfec@syzkaller.appspotmail.com
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
---
 drivers/net/phy/mdio_bus.c | 4 +++-
 include/linux/phy.h        | 1 +
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
index 53f034fc2ef7..ed764638b449 100644
--- a/drivers/net/phy/mdio_bus.c
+++ b/drivers/net/phy/mdio_bus.c
@@ -540,6 +540,8 @@ int __mdiobus_register(struct mii_bus *bus, struct module *owner)
 		return -EINVAL;
 	}
 
+	bus->state = MDIOBUS_DEV_REGISTERED;
+
 	mutex_init(&bus->mdio_lock);
 	mutex_init(&bus->shared_lock);
 
@@ -647,7 +649,7 @@ void mdiobus_free(struct mii_bus *bus)
 		return;
 	}
 
-	BUG_ON(bus->state != MDIOBUS_UNREGISTERED);
+	BUG_ON(bus->state != MDIOBUS_UNREGISTERED && bus->state != MDIOBUS_DEV_REGISTERED);
 	bus->state = MDIOBUS_RELEASED;
 
 	put_device(&bus->dev);
diff --git a/include/linux/phy.h b/include/linux/phy.h
index 736e1d1a47c4..41d2ccdacd5e 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -343,6 +343,7 @@ struct mii_bus {
 		MDIOBUS_REGISTERED,
 		MDIOBUS_UNREGISTERED,
 		MDIOBUS_RELEASED,
+		MDIOBUS_DEV_REGISTERED,
 	} state;
 
 	/** @dev: Kernel device representation */
-- 
2.33.0


^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [PATCH] phy: mdio: fix memory leak
  2021-09-27 11:20 [PATCH] phy: mdio: fix memory leak Pavel Skripkin
@ 2021-09-27 19:17 ` Pavel Skripkin
  2021-09-28 20:39 ` [PATCH v2 1/2] Revert "net: mdiobus: Fix memory leak in __mdiobus_register" Pavel Skripkin
  1 sibling, 0 replies; 8+ messages in thread
From: Pavel Skripkin @ 2021-09-27 19:17 UTC (permalink / raw)
  To: andrew, hkallweit1, linux, davem, kuba, buytenh
  Cc: netdev, linux-kernel, syzbot+398e7dc692ddbbb4cfec

On 9/27/21 14:20, Pavel Skripkin wrote:
> Syzbot reported memory leak in MDIO bus interface, the problem was in
> wrong state logic.
> 
> MDIOBUS_ALLOCATED indicates 2 states:
> 	1. Bus is only allocated
> 	2. Bus allocated and __mdiobus_register() fails, but
> 	   device_register() was called
> 
> In case of device_register() has been called we should call put_device()
> to correctly free the memory allocated for this device, but mdiobus_free()
> was just calling kfree(dev) in case of MDIOBUS_ALLOCATED state
> 
> To avoid this behaviour we can add new intermediate state, which means,
> that we have called device_regiter(), but failed on any of the next steps.
> Clean up process for this state is the same as for MDIOBUS_UNREGISTERED,
> but MDIOBUS_UNREGISTERED name does not fit to the logic described above.
> 
> Fixes: 46abc02175b3 ("phylib: give mdio buses a device tree presence")
> Reported-and-tested-by: syzbot+398e7dc692ddbbb4cfec@syzkaller.appspotmail.com
> Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>


I've just found, that this syzkaller bug has been closed by Yanfei's 
patch [1], but Yanfei's Reported-by: is wrong, IMO.

Yanfei's patch fixed other memory leak and it's not related to bug 
reported by syzkaller. If you take a look at log [2] you won't find 
error message about mii_bus registration failure, i.e the error happened 
a bit latter (more precisely in mdiobus_scan()).

Since, Yanfei's patch is already applied, we cannot remove this tag, so 
I am informing you about this situation to break possible confusions 
about 2 different patches with same Reported-by: tag :)


Thanks


[1] 
https://lore.kernel.org/netdev/20210926045313.2267655-1-yanfei.xu@windriver.com/

[2] https://syzkaller.appspot.com/text?tag=CrashLog&x=131c754b300000


With regards,
Pavel Skripkin

^ permalink raw reply	[flat|nested] 8+ messages in thread

* [PATCH v2 1/2] Revert "net: mdiobus: Fix memory leak in __mdiobus_register"
  2021-09-27 11:20 [PATCH] phy: mdio: fix memory leak Pavel Skripkin
  2021-09-27 19:17 ` Pavel Skripkin
@ 2021-09-28 20:39 ` Pavel Skripkin
  2021-09-28 20:40   ` [PATCH v2 2/2] phy: mdio: fix memory leak Pavel Skripkin
  2021-09-29  6:32   ` [PATCH v2 1/2] Revert "net: mdiobus: Fix memory leak in __mdiobus_register" Xu, Yanfei
  1 sibling, 2 replies; 8+ messages in thread
From: Pavel Skripkin @ 2021-09-28 20:39 UTC (permalink / raw)
  To: andrew, hkallweit1, linux, davem, kuba, buytenh, afleming, dan.carpenter
  Cc: netdev, linux-kernel, Pavel Skripkin, Yanfei Xu

This reverts commit ab609f25d19858513919369ff3d9a63c02cd9e2e.

This patch is correct in the sense that we _should_ call device_put() in
case of device_register() failure, but the problem in this code is more
vast.

We need to set bus->state to UNMDIOBUS_REGISTERED before calling
device_register() to correctly release the device in mdiobus_free().
This patch prevents us from doing it, since in case of device_register()
failure put_device() will be called 2 times and it will cause UAF or
something else.

Also, Reported-by: tag in revered commit was wrong, since syzbot
reported different leak in same function.

Link: https://lore.kernel.org/netdev/20210928092657.GI2048@kadam/
Cc: Yanfei Xu <yanfei.xu@windriver.com>
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
---

Changes in v2:
	Added this revert

---
 drivers/net/phy/mdio_bus.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
index 6f4b4e5df639..53f034fc2ef7 100644
--- a/drivers/net/phy/mdio_bus.c
+++ b/drivers/net/phy/mdio_bus.c
@@ -537,7 +537,6 @@ int __mdiobus_register(struct mii_bus *bus, struct module *owner)
 	err = device_register(&bus->dev);
 	if (err) {
 		pr_err("mii_bus %s failed to register\n", bus->id);
-		put_device(&bus->dev);
 		return -EINVAL;
 	}
 
-- 
2.33.0


^ permalink raw reply	[flat|nested] 8+ messages in thread

* [PATCH v2 2/2] phy: mdio: fix memory leak
  2021-09-28 20:39 ` [PATCH v2 1/2] Revert "net: mdiobus: Fix memory leak in __mdiobus_register" Pavel Skripkin
@ 2021-09-28 20:40   ` Pavel Skripkin
  2021-09-29  6:22     ` Dan Carpenter
  2021-09-29 23:48     ` Jakub Kicinski
  2021-09-29  6:32   ` [PATCH v2 1/2] Revert "net: mdiobus: Fix memory leak in __mdiobus_register" Xu, Yanfei
  1 sibling, 2 replies; 8+ messages in thread
From: Pavel Skripkin @ 2021-09-28 20:40 UTC (permalink / raw)
  To: andrew, hkallweit1, linux, davem, kuba, buytenh, afleming, dan.carpenter
  Cc: netdev, linux-kernel, Pavel Skripkin, syzbot+398e7dc692ddbbb4cfec

Syzbot reported memory leak in MDIO bus interface, the problem was in
wrong state logic.

MDIOBUS_ALLOCATED indicates 2 states:
	1. Bus is only allocated
	2. Bus allocated and __mdiobus_register() fails, but
	   device_register() was called

In case of device_register() has been called we should call put_device()
to correctly free the memory allocated for this device, but mdiobus_free()
calls just kfree(dev) in case of MDIOBUS_ALLOCATED state

To avoid this behaviour we need to set bus->state to MDIOBUS_UNREGISTERED
_before_ calling device_register(), because put_device() should be
called even in case of device_register() failure.

Link: https://lore.kernel.org/netdev/YVMRWNDZDUOvQjHL@shell.armlinux.org.uk/
Fixes: 46abc02175b3 ("phylib: give mdio buses a device tree presence")
Reported-and-tested-by: syzbot+398e7dc692ddbbb4cfec@syzkaller.appspotmail.com
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
---

Changes in v2:
	Removed new state, since MDIOBUS_UNREGISTERED can be used. Also, moved
	bus->state initialization _before_ device_register() call, because
	Yanfei's patch is reverted in [v2 1/2]

---
 drivers/net/phy/mdio_bus.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
index 53f034fc2ef7..2d16a93af1ae 100644
--- a/drivers/net/phy/mdio_bus.c
+++ b/drivers/net/phy/mdio_bus.c
@@ -534,6 +534,13 @@ int __mdiobus_register(struct mii_bus *bus, struct module *owner)
 	bus->dev.groups = NULL;
 	dev_set_name(&bus->dev, "%s", bus->id);
 
+	/* We need to set state to MDIOBUS_UNREGISTERED to correctly realese
+	 * the device in mdiobus_free()
+	 *
+	 * State will be updated later in this function in case of success
+	 */
+	bus->state == MDIOBUS_UNREGISTERED;
+
 	err = device_register(&bus->dev);
 	if (err) {
 		pr_err("mii_bus %s failed to register\n", bus->id);
-- 
2.33.0


^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [PATCH v2 2/2] phy: mdio: fix memory leak
  2021-09-28 20:40   ` [PATCH v2 2/2] phy: mdio: fix memory leak Pavel Skripkin
@ 2021-09-29  6:22     ` Dan Carpenter
  2021-09-29 23:48     ` Jakub Kicinski
  1 sibling, 0 replies; 8+ messages in thread
From: Dan Carpenter @ 2021-09-29  6:22 UTC (permalink / raw)
  To: Pavel Skripkin
  Cc: andrew, hkallweit1, linux, davem, kuba, buytenh, afleming,
	netdev, linux-kernel, syzbot+398e7dc692ddbbb4cfec

On Tue, Sep 28, 2021 at 11:40:15PM +0300, Pavel Skripkin wrote:
> Syzbot reported memory leak in MDIO bus interface, the problem was in
> wrong state logic.
> 
> MDIOBUS_ALLOCATED indicates 2 states:
> 	1. Bus is only allocated
> 	2. Bus allocated and __mdiobus_register() fails, but
> 	   device_register() was called
> 
> In case of device_register() has been called we should call put_device()
> to correctly free the memory allocated for this device, but mdiobus_free()
> calls just kfree(dev) in case of MDIOBUS_ALLOCATED state
> 
> To avoid this behaviour we need to set bus->state to MDIOBUS_UNREGISTERED
> _before_ calling device_register(), because put_device() should be
> called even in case of device_register() failure.
> 
> Link: https://lore.kernel.org/netdev/YVMRWNDZDUOvQjHL@shell.armlinux.org.uk/ 
> Fixes: 46abc02175b3 ("phylib: give mdio buses a device tree presence")
> Reported-and-tested-by: syzbot+398e7dc692ddbbb4cfec@syzkaller.appspotmail.com
> Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>

Thanks!

Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>

regards,
dan carpenter


^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [PATCH v2 1/2] Revert "net: mdiobus: Fix memory leak in __mdiobus_register"
  2021-09-28 20:39 ` [PATCH v2 1/2] Revert "net: mdiobus: Fix memory leak in __mdiobus_register" Pavel Skripkin
  2021-09-28 20:40   ` [PATCH v2 2/2] phy: mdio: fix memory leak Pavel Skripkin
@ 2021-09-29  6:32   ` Xu, Yanfei
  1 sibling, 0 replies; 8+ messages in thread
From: Xu, Yanfei @ 2021-09-29  6:32 UTC (permalink / raw)
  To: Pavel Skripkin, andrew, hkallweit1, linux, davem, kuba, buytenh,
	afleming, dan.carpenter
  Cc: netdev, linux-kernel



On 9/29/21 4:39 AM, Pavel Skripkin wrote:
> This reverts commit ab609f25d19858513919369ff3d9a63c02cd9e2e.
> 
> This patch is correct in the sense that we_should_  call device_put() in
> case of device_register() failure, but the problem in this code is more
> vast.
> 
> We need to set bus->state to UNMDIOBUS_REGISTERED before calling
> device_register() to correctly release the device in mdiobus_free().
> This patch prevents us from doing it, since in case of device_register()
> failure put_device() will be called 2 times and it will cause UAF or
> something else.
> 
> Also, Reported-by: tag in revered commit was wrong, since syzbot
> reported different leak in same function.
> 
> Link:https://lore.kernel.org/netdev/20210928092657.GI2048@kadam/
> Cc: Yanfei Xu<yanfei.xu@windriver.com>
> Signed-off-by: Pavel Skripkin<paskripkin@gmail.com>
> ---
> 
> Changes in v2:
>          Added this revert


Acked-by: Yanfei Xu<yanfei.xu@windriver.com>

Thanks,
Yanfei

^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [PATCH v2 2/2] phy: mdio: fix memory leak
  2021-09-28 20:40   ` [PATCH v2 2/2] phy: mdio: fix memory leak Pavel Skripkin
  2021-09-29  6:22     ` Dan Carpenter
@ 2021-09-29 23:48     ` Jakub Kicinski
  2021-09-30  5:55       ` Pavel Skripkin
  1 sibling, 1 reply; 8+ messages in thread
From: Jakub Kicinski @ 2021-09-29 23:48 UTC (permalink / raw)
  To: Pavel Skripkin
  Cc: andrew, hkallweit1, linux, davem, buytenh, afleming,
	dan.carpenter, netdev, linux-kernel, syzbot+398e7dc692ddbbb4cfec

On Tue, 28 Sep 2021 23:40:15 +0300 Pavel Skripkin wrote:
> +	/* We need to set state to MDIOBUS_UNREGISTERED to correctly realese
> +	 * the device in mdiobus_free()
> +	 *
> +	 * State will be updated later in this function in case of success
> +	 */
> +	bus->state == MDIOBUS_UNREGISTERED;

IDK how syzbot has tested it but clearly we should blindly 
depend on that.

s/==/=/

Compiler would have told you this.

^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [PATCH v2 2/2] phy: mdio: fix memory leak
  2021-09-29 23:48     ` Jakub Kicinski
@ 2021-09-30  5:55       ` Pavel Skripkin
  0 siblings, 0 replies; 8+ messages in thread
From: Pavel Skripkin @ 2021-09-30  5:55 UTC (permalink / raw)
  To: Jakub Kicinski
  Cc: andrew, hkallweit1, linux, davem, buytenh, afleming,
	dan.carpenter, netdev, linux-kernel, syzbot+398e7dc692ddbbb4cfec

On 9/30/21 02:48, Jakub Kicinski wrote:
> On Tue, 28 Sep 2021 23:40:15 +0300 Pavel Skripkin wrote:
>> +	/* We need to set state to MDIOBUS_UNREGISTERED to correctly realese
>> +	 * the device in mdiobus_free()
>> +	 *
>> +	 * State will be updated later in this function in case of success
>> +	 */
>> +	bus->state == MDIOBUS_UNREGISTERED;
> 
> IDK how syzbot has tested it but clearly we should blindly
> depend on that.
> 
> s/==/=/
> 
> Compiler would have told you this.
> 
whooops... sorry about that. syzbot has tested v1. v2 is same, but 
without new state (so, the logic in v1 and v2 is the same).

I guess, it's copy-paste error on my side :). Will send v3 this evening



With regards,
Pavel Skripkin

^ permalink raw reply	[flat|nested] 8+ messages in thread

end of thread, other threads:[~2021-09-30  5:56 UTC | newest]

Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-09-27 11:20 [PATCH] phy: mdio: fix memory leak Pavel Skripkin
2021-09-27 19:17 ` Pavel Skripkin
2021-09-28 20:39 ` [PATCH v2 1/2] Revert "net: mdiobus: Fix memory leak in __mdiobus_register" Pavel Skripkin
2021-09-28 20:40   ` [PATCH v2 2/2] phy: mdio: fix memory leak Pavel Skripkin
2021-09-29  6:22     ` Dan Carpenter
2021-09-29 23:48     ` Jakub Kicinski
2021-09-30  5:55       ` Pavel Skripkin
2021-09-29  6:32   ` [PATCH v2 1/2] Revert "net: mdiobus: Fix memory leak in __mdiobus_register" Xu, Yanfei

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