[PATCH 1/2] winealsa: Don't acquire the sessions lock after the client lock.

[Huw Davies]

This could lead to a deadlock with AudioSessionControl_GetState()
which acquires the locks in the other order.

Signed-off-by: Huw Davies 
---
 dlls/winealsa.drv/mmdevdrv.c | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/dlls/winealsa.drv/mmdevdrv.c b/dlls/winealsa.drv/mmdevdrv.c
index 7f25cdcce1b..5aa1b4aab63 100644
--- a/dlls/winealsa.drv/mmdevdrv.c
+++ b/dlls/winealsa.drv/mmdevdrv.c
@@ -1344,10 +1344,12 @@ static HRESULT WINAPI AudioClient_Initialize(IAudioClient3 *iface,
         }
     }

+    EnterCriticalSection(&g_sessions_lock);
     EnterCriticalSection(&This->lock);

if(This->initted){
         LeaveCriticalSection(&This->lock);
+        LeaveCriticalSection(&g_sessions_lock);
         return AUDCLNT_E_ALREADY_INITIALIZED;
     }

@@ -1537,19 +1539,13 @@ static HRESULT WINAPI AudioClient_Initialize(IAudioClient3 *iface,
     This->share = mode;
     This->flags = flags;

-    EnterCriticalSection(&g_sessions_lock);
-
     hr = get_audio_session(sessionguid, This->parent, fmt->nChannels,
             &This->session);
-    if(FAILED(hr)){
-        LeaveCriticalSection(&g_sessions_lock);
+    if(FAILED(hr))
         goto exit;
-    }

list_add_tail(&This->session->clients, &This->entry);

-    LeaveCriticalSection(&g_sessions_lock);
-
     This->initted = TRUE;

TRACE("ALSA period: %lu frames\n", This->alsa_period_frames);
@@ -1569,6 +1565,7 @@ exit:
     }

LeaveCriticalSection(&This->lock);
+    LeaveCriticalSection(&g_sessions_lock);

return hr;
 }

[Andrew Eikum]

Signed-off-by: Andrew Eikum

On Thu, Dec 02, 2021 at 12:02:38PM +0000, Huw Davies wrote:
> This could lead to a deadlock with AudioSessionControl_GetState()
> which acquires the locks in the other order.
> Signed-off-by: Huw Davies
>
> dlls/winealsa.drv/mmdevdrv.c | 11 ++++-------
>  1 file changed, 4 insertions(+), 7 deletions(-)
>
> diff --git a/dlls/winealsa.drv/mmdevdrv.c b/dlls/winealsa.drv/mmdevdrv.c
> index 7f25cdcce1b..5aa1b4aab63 100644
> --- a/dlls/winealsa.drv/mmdevdrv.c
> +++ b/dlls/winealsa.drv/mmdevdrv.c
> @@ -1344,10 +1344,12 @@ static HRESULT WINAPI AudioClient_Initialize(IAudioClient3 *iface,
>          }
>      }
> -
>
> EnterCriticalSection(&g_sessions_lock);
> EnterCriticalSection(&This->lock);
>
> if(This->initted){
>     LeaveCriticalSection(&This->lock);
> -
>    LeaveCriticalSection(&g_sessions_lock);
>    return AUDCLNT_E_ALREADY_INITIALIZED;
>
> }
>
> @@ -1537,19 +1539,13 @@ static HRESULT WINAPI AudioClient_Initialize(IAudioClient3 *iface,
>      This->share = mode;
>      This->flags = flags;
> - EnterCriticalSection(&g_sessions_lock);
> - hr = get_audio_session(sessionguid, This->parent, fmt->nChannels,
>            &This->session);
> - if(FAILED(hr)){
> -
>    LeaveCriticalSection(&g_sessions_lock);
> - if(FAILED(hr))
>     goto exit;
> -
>
> }
>
> list_add_tail(&This->session->clients, &This->entry);
> -
>
> LeaveCriticalSection(&g_sessions_lock);
> -
>
> This->initted = TRUE;
>
> TRACE("ALSA period: %lu frames\n", This->alsa_period_frames);
>
> @@ -1569,6 +1565,7 @@ exit:
>      }
>  LeaveCriticalSection(&This->lock);
> -
>
> LeaveCriticalSection(&g_sessions_lock);
>
> return hr;
> }
>
> 2.23.0