firmware loader: Fix the concurrent request_firmware() race for kref_get/put
There is one race that both request_firmware() with the same firmware name. The race scenerio is as below: CPU1 CPU2 request_firmware() --> _request_firmware_load() return err another request_firmware() is coming --> _request_firmware_cleanup is called --> _request_firmware_prepare --> release_firmware ---> fw_lookup_and_allocate_buf --> spin_lock(&fwc->lock) ... __fw_lookup_buf() return true fw_free_buf() will be called --> ... kref_put --> decrease the refcount to 0 kref_get(&tmp->ref) ==> it will trigger warning due to refcount == 0 __fw_free_buf() --> ... spin_unlock(&fwc->lock) spin_lock(&fwc->lock) list_del(&buf->list) spin_unlock(&fwc->lock) kfree(buf) After that, the freed buf will be used. The key race is decreasing refcount to 0 and list_del is not protected together by fwc->lock, and it is possible another thread try to get it between refcount==0 and list_del. Fix it here to protect it together. Acked-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: liu chuansheng <chuansheng.liu@intel.com> Cc: stable <stable@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
parent
ce2fcbd99c
commit
bd9eb7fbe6
|
@ -246,7 +246,6 @@ static void __fw_free_buf(struct kref *ref)
|
|||
__func__, buf->fw_id, buf, buf->data,
|
||||
(unsigned int)buf->size);
|
||||
|
||||
spin_lock(&fwc->lock);
|
||||
list_del(&buf->list);
|
||||
spin_unlock(&fwc->lock);
|
||||
|
||||
|
@ -263,7 +262,10 @@ static void __fw_free_buf(struct kref *ref)
|
|||
|
||||
static void fw_free_buf(struct firmware_buf *buf)
|
||||
{
|
||||
kref_put(&buf->ref, __fw_free_buf);
|
||||
struct firmware_cache *fwc = buf->fwc;
|
||||
spin_lock(&fwc->lock);
|
||||
if (!kref_put(&buf->ref, __fw_free_buf))
|
||||
spin_unlock(&fwc->lock);
|
||||
}
|
||||
|
||||
/* direct firmware loading support */
|
||||
|
|
Loading…
Reference in a new issue