2023-04-13 22:23:24

by Conor Dooley

Subject: [PATCH v1] clk: microchip: fix potential UAF in auxdev release callback

From: Conor Dooley <[email protected]>

Similar to commit 1c11289b34ab ("peci: cpu: Fix use-after-free in
adev_release()"), the auxiliary device is not torn down in the correct
order. If auxiliary_device_add() fails, the release callback will be
called twice, resulting in a UAF. Due to timing, the auxdev code in this
driver "took inspiration" from the aforementioned commit, and thus its
bugs too!

Moving auxiliary_device_uninit() to the unregister callback instead
avoids the issue.

CC: [email protected]
Fixes: b56bae2dd6fd ("clk: microchip: mpfs: add reset controller")
Signed-off-by: Conor Dooley <[email protected]>
---
Stephen,
Claudiu is on leave at the moment, and although I can push stuff to the
at-91 tree etc, it's probably simpler if you just take this yourself?

CC: Stephen Boyd <[email protected]>
CC: Conor Dooley <[email protected]>
CC: Daire McNamara <[email protected]>
CC: Michael Turquette <[email protected]>
CC: Stephen Boyd <[email protected]>
CC: Claudiu Beznea <[email protected]>
CC: [email protected]
CC: [email protected]
---
drivers/clk/microchip/clk-mpfs.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/clk/microchip/clk-mpfs.c b/drivers/clk/microchip/clk-mpfs.c
index 4f0a19db7ed7..cc5d7dee59f0 100644
--- a/drivers/clk/microchip/clk-mpfs.c
+++ b/drivers/clk/microchip/clk-mpfs.c
@@ -374,14 +374,13 @@ static void mpfs_reset_unregister_adev(void *_adev)
struct auxiliary_device *adev = _adev;

auxiliary_device_delete(adev);
+ auxiliary_device_uninit(adev);
}

static void mpfs_reset_adev_release(struct device *dev)
{
struct auxiliary_device *adev = to_auxiliary_dev(dev);

- auxiliary_device_uninit(adev);
-
kfree(adev);
}

--
2.39.2

2023-04-13 22:44:08

by Stephen Boyd

Subject: Re: [PATCH v1] clk: microchip: fix potential UAF in auxdev release callback

Quoting Conor Dooley (2023-04-13 15:20:45)
> From: Conor Dooley <[email protected]>
>
> Similar to commit 1c11289b34ab ("peci: cpu: Fix use-after-free in
> adev_release()"), the auxiliary device is not torn down in the correct
> order. If auxiliary_device_add() fails, the release callback will be
> called twice, resulting in a UAF. Due to timing, the auxdev code in this
> driver "took inspiration" from the aforementioned commit, and thus its
> bugs too!
>
> Moving auxiliary_device_uninit() to the unregister callback instead
> avoids the issue.
>
> CC: [email protected]
> Fixes: b56bae2dd6fd ("clk: microchip: mpfs: add reset controller")
> Signed-off-by: Conor Dooley <[email protected]>
> ---

Applied to clk-next