2011-07-22 22:07:15

by Pavel Roskin

Subject: [PATCH] b43: fix invalid memory access in b43_ssb_remove()

wldev is freed in b43_one_core_detach() and should not be accessed after
that call. Keep wldev->dev in a local variable.

Signed-off-by: Pavel Roskin <[email protected]>
---

Linux 3.0 is not affected. The bug was introduced in 482f0538.

drivers/net/wireless/b43/main.c | 5 +++--
1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/b43/main.c b/drivers/net/wireless/b43/main.c
index d9f53b7..85d6a1f 100644
--- a/drivers/net/wireless/b43/main.c
+++ b/drivers/net/wireless/b43/main.c
@@ -5350,6 +5350,7 @@ static void b43_ssb_remove(struct ssb_device *sdev)
{
struct b43_wl *wl = ssb_get_devtypedata(sdev);
struct b43_wldev *wldev = ssb_get_drvdata(sdev);
+ struct b43_bus_dev *dev = wldev->dev;

/* We must cancel any work here before unregistering from ieee80211,
* as the ieee80211 unreg will destroy the workqueue. */
@@ -5365,14 +5366,14 @@ static void b43_ssb_remove(struct ssb_device *sdev)
ieee80211_unregister_hw(wl->hw);
}

- b43_one_core_detach(wldev->dev);
+ b43_one_core_detach(dev);

if (list_empty(&wl->devlist)) {
b43_leds_unregister(wl);
/* Last core on the chip unregistered.
* We can destroy common struct b43_wl.
*/
- b43_wireless_exit(wldev->dev, wl);
+ b43_wireless_exit(dev, wl);
}
}

2011-07-25 16:27:00

by Pavel Roskin

Subject: Re: [PATCH] b43: fix invalid memory access in b43_ssb_remove()

On 07/22/2011 06:07 PM, Pavel Roskin wrote:
> wldev is freed in b43_one_core_detach() and should not be accessed after
> that call. Keep wldev->dev in a local variable.
>
> Signed-off-by: Pavel Roskin<[email protected]>
> ---
>
> Linux 3.0 is not affected. The bug was introduced in 482f0538.

P.S. This needs to be propagated to Linux 3.1.

> - b43_one_core_detach(wldev->dev);
> + b43_one_core_detach(dev);

As a long term solution, we probably want a function that takes wldev
and has "free" in its name, so that the effect is clear.

--
Regards,
Pavel Roskin