mm-video-v4l2: venc: Protect buffer from being freed while accessing

Output buffer (in use-buffer mode) has an internal backup ion buffer.
The contents of this buffer are deep-copied in client's buffer in
the context of VideoEncCallBackThread; while this buffer can be
freed in the client thread's context.
Check the allocation bitmask before attempting to copy and
synchronize these operations by holding a lock

Fixes bug 36130225
 Security Vulnerability - Heap use after free in libOmxVenc

CRs-Fixed: 2053101

Change-Id: I6141e81d7dbd50bc3601c8df066fd8cbd06b4e0b

3 files changed, 16 insertions, 1 deletions

diff --git a/mm-video-v4l2/vidc/venc/inc/omx_video_base.h b/mm-video-v4l2/vidc/venc/inc/omx_video_base.h
index 3daf08cd..08a43603 100644
--- a/mm-video-v4l2/vidc/venc/inc/omx_video_base.h
+++ b/mm-video-v4l2/vidc/venc/inc/omx_video_base.h
@@ -645,6 +645,7 @@ class omx_video: public qc_omx_component
         omx_cmd_queue m_opq_meta_q;
         omx_cmd_queue m_opq_pmem_q;
         OMX_BUFFERHEADERTYPE meta_buffer_hdr[MAX_NUM_INPUT_BUFFERS];
+        pthread_mutex_t m_buf_lock;
 
         bool input_flush_progress;
         bool output_flush_progress;
diff --git a/mm-video-v4l2/vidc/venc/src/omx_video_base.cpp b/mm-video-v4l2/vidc/venc/src/omx_video_base.cpp
index ba071037..c3696ec2 100644
--- a/mm-video-v4l2/vidc/venc/src/omx_video_base.cpp
+++ b/mm-video-v4l2/vidc/venc/src/omx_video_base.cpp
@@ -258,6 +258,8 @@ omx_video::omx_video():
     pthread_mutex_init(&m_lock, NULL);
     sem_init(&m_cmd_lock,0,0);
     DEBUG_PRINT_LOW("meta_buffer_hdr = %p", meta_buffer_hdr);
+
+    pthread_mutex_init(&m_buf_lock, NULL);
 }
 
 
@@ -293,6 +295,8 @@ omx_video::~omx_video()
     sem_destroy(&m_cmd_lock);
     DEBUG_PRINT_HIGH("m_etb_count = %" PRIu64" , m_fbd_count = %" PRIu64, m_etb_count,
             m_fbd_count);
+
+    pthread_mutex_destroy(&m_buf_lock);
     DEBUG_PRINT_HIGH("omx_video: Destructor exit");
     DEBUG_PRINT_HIGH("Exiting OMX Video Encoder ...");
 }
@@ -2396,6 +2400,7 @@ OMX_ERRORTYPE  omx_video::use_output_buffer(
         return OMX_ErrorBadParameter;
     }
 
+    auto_lock l(m_buf_lock);
     if (!m_out_mem_ptr) {
         output_use_buffer = true;
         int nBufHdrSize        = 0;
@@ -3322,6 +3327,7 @@ OMX_ERRORTYPE  omx_video::free_buffer(OMX_IN OMX_HANDLETYPE         hComp,
                 nPortIndex, (unsigned int)m_sOutPortDef.nBufferCountActual);
         if (nPortIndex < m_sOutPortDef.nBufferCountActual &&
                 BITMASK_PRESENT(&m_out_bm_count, nPortIndex)) {
+            auto_lock l(m_buf_lock);
             // Clear the bit associated with it.
             BITMASK_CLEAR(&m_out_bm_count,nPortIndex);
             m_sOutPortDef.bPopulated = OMX_FALSE;
diff --git a/mm-video-v4l2/vidc/venc/src/omx_video_encoder.cpp b/mm-video-v4l2/vidc/venc/src/omx_video_encoder.cpp
index b6e7fd87..c05a73af 100644
--- a/mm-video-v4l2/vidc/venc/src/omx_video_encoder.cpp
+++ b/mm-video-v4l2/vidc/venc/src/omx_video_encoder.cpp
@@ -2214,10 +2214,17 @@ int omx_venc::async_message_process (void *context, void* message)
                     OMX_COMPONENT_GENERATE_EBD);
             break;
         case VEN_MSG_OUTPUT_BUFFER_DONE:
+        {
             omxhdr = (OMX_BUFFERHEADERTYPE*)m_sVenc_msg->buf.clientdata;
+            OMX_U32 bufIndex = (OMX_U32)(omxhdr - omx->m_out_mem_ptr);
 
             if ( (omxhdr != NULL) &&
-                    ((OMX_U32)(omxhdr - omx->m_out_mem_ptr)  < omx->m_sOutPortDef.nBufferCountActual)) {
+                    (bufIndex  < omx->m_sOutPortDef.nBufferCountActual)) {
+                auto_lock l(omx->m_buf_lock);
+                if (BITMASK_ABSENT(&(omx->m_out_bm_count), bufIndex)) {
+                    DEBUG_PRINT_ERROR("Recieved FBD for buffer that is already freed !");
+                    break;
+                }
                 if (!omx->is_secure_session() && (m_sVenc_msg->buf.len <=  omxhdr->nAllocLen)) {
                     omxhdr->nFilledLen = m_sVenc_msg->buf.len;
                     omxhdr->nOffset = m_sVenc_msg->buf.offset;
@@ -2251,6 +2258,7 @@ int omx_venc::async_message_process (void *context, void* message)
             omx->post_event ((unsigned long)omxhdr,m_sVenc_msg->statuscode,
                     OMX_COMPONENT_GENERATE_FBD);
             break;
+        }
         case VEN_MSG_NEED_OUTPUT_BUFFER:
             //TBD what action needs to be done here??
             break;