[PATCH 0/2] net: fix use-after-free bugs

[PATCH 0/2] net: fix use-after-free bugs

[Pavel Skripkin]

I've added new checker to smatch yesterday. It warns about using
netdev_priv() pointer after free_{netdev,candev}() call. I hope, it will
get into next smatch release.

Some of the reported bugs are fixed and upstreamed already, but Dan ran new
smatch with allmodconfig and found 2 more. Big thanks to Dan for doing it,
because I totally forgot to do it.

Pavel Skripkin (2):
  net: fec: fix use-after-free in fec_drv_remove
  net: vxge: fix use-after-free in vxge_device_unregister

 drivers/net/ethernet/freescale/fec_main.c      | 2 +-
 drivers/net/ethernet/neterion/vxge/vxge-main.c | 6 +++---
 2 files changed, 4 insertions(+), 4 deletions(-)

-- 
2.32.0

[PATCH 1/2] net: fec: fix use-after-free in fec_drv_remove

[Pavel Skripkin]

Smatch says:
	drivers/net/ethernet/freescale/fec_main.c:3994 fec_drv_remove() error: Using fep after free_{netdev,candev}(ndev);
	drivers/net/ethernet/freescale/fec_main.c:3995 fec_drv_remove() error: Using fep after free_{netdev,candev}(ndev);

Since fep pointer is netdev private data, accessing it after free_netdev()
call can cause use-after-free bug. Fix it by moving free_netdev() call at
the end of the function

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Fixes: a31eda65ba21 ("net: fec: fix clock count mis-match")
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
---
 drivers/net/ethernet/freescale/fec_main.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index 8aea707a65a7..7e4c4980ced7 100644
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -3843,13 +3843,13 @@ fec_drv_remove(struct platform_device *pdev)
 	if (of_phy_is_fixed_link(np))
 		of_phy_deregister_fixed_link(np);
 	of_node_put(fep->phy_node);
-	free_netdev(ndev);
 
 	clk_disable_unprepare(fep->clk_ahb);
 	clk_disable_unprepare(fep->clk_ipg);
 	pm_runtime_put_noidle(&pdev->dev);
 	pm_runtime_disable(&pdev->dev);
 
+	free_netdev(ndev);
 	return 0;
 }
 
-- 
2.32.0

[PATCH 2/2] net: vxge: fix use-after-free in vxge_device_unregister

[Pavel Skripkin]

Smatch says:
drivers/net/ethernet/neterion/vxge/vxge-main.c:3518 vxge_device_unregister() error: Using vdev after free_{netdev,candev}(dev);
drivers/net/ethernet/neterion/vxge/vxge-main.c:3518 vxge_device_unregister() error: Using vdev after free_{netdev,candev}(dev);
drivers/net/ethernet/neterion/vxge/vxge-main.c:3520 vxge_device_unregister() error: Using vdev after free_{netdev,candev}(dev);
drivers/net/ethernet/neterion/vxge/vxge-main.c:3520 vxge_device_unregister() error: Using vdev after free_{netdev,candev}(dev);

Since vdev pointer is netdev private data accessing it after free_netdev()
call can cause use-after-free bug. Fix it by moving free_netdev() call at
the end of the function

Fixes: 6cca200362b4 ("vxge: cleanup probe error paths")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
---
 drivers/net/ethernet/neterion/vxge/vxge-main.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/neterion/vxge/vxge-main.c b/drivers/net/ethernet/neterion/vxge/vxge-main.c
index 82eef4c72f01..7abd13e69471 100644
--- a/drivers/net/ethernet/neterion/vxge/vxge-main.c
+++ b/drivers/net/ethernet/neterion/vxge/vxge-main.c
@@ -3512,13 +3512,13 @@ static void vxge_device_unregister(struct __vxge_hw_device *hldev)
 
 	kfree(vdev->vpaths);
 
-	/* we are safe to free it now */
-	free_netdev(dev);
-
 	vxge_debug_init(vdev->level_trace, "%s: ethernet device unregistered",
 			buf);
 	vxge_debug_entryexit(vdev->level_trace,	"%s: %s:%d  Exiting...", buf,
 			     __func__, __LINE__);
+
+	/* we are safe to free it now */
+	free_netdev(dev);
 }
 
 /*
-- 
2.32.0

Re: [PATCH 0/2] net: fix use-after-free bugs

[Jesse Brandeburg]

On 8/4/2021 8:48 AM, Pavel Skripkin wrote:
> I've added new checker to smatch yesterday. It warns about using
> netdev_priv() pointer after free_{netdev,candev}() call. I hope, it will
> get into next smatch release.
>
> Some of the reported bugs are fixed and upstreamed already, but Dan ran new
> smatch with allmodconfig and found 2 more. Big thanks to Dan for doing it,
> because I totally forgot to do it.
>
> Pavel Skripkin (2):
>   net: fec: fix use-after-free in fec_drv_remove
>   net: vxge: fix use-after-free in vxge_device_unregister
>
>  drivers/net/ethernet/freescale/fec_main.c      | 2 +-
>  drivers/net/ethernet/neterion/vxge/vxge-main.c | 6 +++---
>  2 files changed, 4 insertions(+), 4 deletions(-)


Looks like a good new check! For the series:

Reviewed-by: Jesse Brandeburg <jesse.brandeburg@intel.com>

RE: [PATCH 1/2] net: fec: fix use-after-free in fec_drv_remove

[Joakim Zhang]

> -----Original Message-----
> From: Pavel Skripkin <paskripkin@gmail.com>
> Sent: 2021年8月4日 23:52
> To: davem@davemloft.net; kuba@kernel.org; Joakim Zhang
> <qiangqing.zhang@nxp.com>; hslester96@gmail.com; fugang.duan@nxp.com
> Cc: dan.carpenter@oracle.com; netdev@vger.kernel.org;
> linux-kernel@vger.kernel.org; Pavel Skripkin <paskripkin@gmail.com>
> Subject: [PATCH 1/2] net: fec: fix use-after-free in fec_drv_remove
> 
> Smatch says:
> 	drivers/net/ethernet/freescale/fec_main.c:3994 fec_drv_remove() error:
> Using fep after free_{netdev,candev}(ndev);
> 	drivers/net/ethernet/freescale/fec_main.c:3995 fec_drv_remove() error:
> Using fep after free_{netdev,candev}(ndev);
> 
> Since fep pointer is netdev private data, accessing it after free_netdev() call can
> cause use-after-free bug. Fix it by moving free_netdev() call at the end of the
> function
> 
> Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
> Fixes: a31eda65ba21 ("net: fec: fix clock count mis-match")
> Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
> ---
Thanks.

Reviewed-by: Joakim Zhang <qiangqing.zhang@nxp.com>

Best Regards,
Joakim Zhang

Re: [PATCH 0/2] net: fix use-after-free bugs

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net.git (refs/heads/master):

On Wed,  4 Aug 2021 18:48:57 +0300 you wrote:
> I've added new checker to smatch yesterday. It warns about using
> netdev_priv() pointer after free_{netdev,candev}() call. I hope, it will
> get into next smatch release.
> 
> Some of the reported bugs are fixed and upstreamed already, but Dan ran new
> smatch with allmodconfig and found 2 more. Big thanks to Dan for doing it,
> because I totally forgot to do it.
> 
> [...]

Here is the summary with links:
  - [1/2] net: fec: fix use-after-free in fec_drv_remove
    https://git.kernel.org/netdev/net/c/44712965bf12
  - [2/2] net: vxge: fix use-after-free in vxge_device_unregister
    https://git.kernel.org/netdev/net/c/942e560a3d38

You are awesome, thank you!
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