On 30.05.22 09:08, Muchun Song wrote:
On Mon, May 30, 2022 at 2:56 PM David Hildenbrand david@redhat.com wrote:
On 30.05.22 07:33, Muchun Song wrote:
The device_unregister() is supposed to be used to unregister devices if device_register() has succeed. And device_unregister() will put device. The caller should not do it again, otherwise, the first call of put_device() will drop the last reference count, then the next call of device_unregister() will UAF on device.
Fixes: 4fb6eabf1037 ("drivers/base/memory.c: cache memory blocks in xarray to accelerate lookup") Signed-off-by: Muchun Song songmuchun@bytedance.com Cc: stable@vger.kernel.org
drivers/base/memory.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/drivers/base/memory.c b/drivers/base/memory.c index 7222ff9b5e05..084d67fd55cc 100644 --- a/drivers/base/memory.c +++ b/drivers/base/memory.c @@ -636,10 +636,9 @@ static int __add_memory_block(struct memory_block *memory) } ret = xa_err(xa_store(&memory_blocks, memory->dev.id, memory, GFP_KERNEL));
if (ret) {put_device(&memory->dev);
if (ret) device_unregister(&memory->dev);
}
return ret;}
See
https://lkml.kernel.org/r/d44c63d78affe844f020dc02ad6af29abc448fc4.165061170...
I see. Good job by Christophe. Thanks David.
I'm curious how both of you found that issue? Just by staring at that code? :)