From: Dan Carpenter <dan.carpenter(a)oracle.com>

stable inclusion from stable-v5.10.44 commit be23c4af3d8a1b986fe9b43b8966797653a76ca4 bugzilla: https://bugzilla.openeuler.org/show_bug.cgi?id=341 CVE: NA

--------------------------------

[ Upstream commit 1dde47a66d4fb181830d6fa000e5ea86907b639e ]

We spotted a bug recently during a review where a driver was unregistering a bus that wasn't registered, which would trigger this BUG_ON(). Let's handle that situation more gracefully, and just print a warning and return.

Reported-by: Russell King (Oracle) <rmk+kernel(a)armlinux.org.uk> Signed-off-by: Dan Carpenter <dan.carpenter(a)oracle.com> Reviewed-by: Russell King (Oracle) <rmk+kernel(a)armlinux.org.uk> Reviewed-by: Andrew Lunn <andrew(a)lunn.ch> Signed-off-by: David S. Miller <davem(a)davemloft.net> Signed-off-by: Sasha Levin <sashal(a)kernel.org> Signed-off-by: wangqing <wangqing(a)uniontech.com> Reviewed-by: Xie XiuQi xiexiuqi@huawei.com Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com --- drivers/net/phy/mdio_bus.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c index 757e950fb745..b848439fa837 100644 --- a/drivers/net/phy/mdio_bus.c +++ b/drivers/net/phy/mdio_bus.c @@ -608,7 +608,8 @@ void mdiobus_unregister(struct mii_bus *bus) struct mdio_device *mdiodev; int i;

- BUG_ON(bus->state != MDIOBUS_REGISTERED); + if (WARN_ON_ONCE(bus->state != MDIOBUS_REGISTERED)) + return; bus->state = MDIOBUS_UNREGISTERED;

for (i = 0; i < PHY_MAX_ADDR; i++) {

Reviewed-by: Wang ShaoBo bobo.shaobowang@huawei.com

在 2021/10/18 10:51, holmes 写道:

From: Desmond Cheong Zhi Xi desmondcheongzx@gmail.com

stable inclusion from stable-v5.10.44 commit aa8591a58cbd2986090709e4202881f18e8ae30e bugzilla:https://bugzilla.openeuler.org/show_bug.cgi?id=435 CVE: NA

---

commit c336a5ee984708db4826ef9e47d184e638e29717 upstream.

This patch eliminates the following smatch warning: drivers/gpu/drm/drm_auth.c:320 drm_master_release() warn: unlocked access 'master' (line 318) expected lock '&dev->master_mutex'

The 'file_priv->master' field should be protected by the mutex lock to '&dev->master_mutex'. This is because other processes can concurrently modify this field and free the current 'file_priv->master' pointer. This could result in a use-after-free error when 'master' is dereferenced in subsequent function calls to 'drm_legacy_lock_master_cleanup()' or to 'drm_lease_revoke()'.

An example of a scenario that would produce this error can be seen from a similar bug in 'drm_getunique()' that was reported by Syzbot: https://syzkaller.appspot.com/bug?id=148d2f1dfac64af52ffd27b661981a540724f80...

In the Syzbot report, another process concurrently acquired the device's master mutex in 'drm_setmaster_ioctl()', then overwrote 'fpriv->master' in 'drm_new_set_master()'. The old value of 'fpriv->master' was subsequently freed before the mutex was unlocked.

Reported-by: Dan Carpenter dan.carpenter@oracle.com Signed-off-by: Desmond Cheong Zhi Xi desmondcheongzx@gmail.com Cc: stable@vger.kernel.org Signed-off-by: Daniel Vetter daniel.vetter@ffwll.ch Link: https://patchwork.freedesktop.org/patch/msgid/20210609092119.173590-1-desmon... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: holmes holmes@my.swjtu.edu.cn

---

drivers/gpu/drm/drm_auth.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_auth.c b/drivers/gpu/drm/drm_auth.c index f2d46b7ac6f9..232abbba3686 100644 --- a/drivers/gpu/drm/drm_auth.c +++ b/drivers/gpu/drm/drm_auth.c @@ -314,9 +314,10 @@ int drm_master_open(struct drm_file *file_priv) void drm_master_release(struct drm_file *file_priv) { struct drm_device *dev = file_priv->minor->dev;

• struct drm_master *master = file_priv->master;

• struct drm_master *master;

  mutex_lock(&dev->master_mutex);

• master = file_priv->master; if (file_priv->magic) idr_remove(&file_priv->master->magic_map, file_priv->magic);