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

Author: Praveen Chavan<pchavan@codeaurora.org>

Change-Id: I6141e81d7dbd50bc3601c8df066fd8cbd06b4e0b
(cherry picked from commit a5698533111c13936e65581ba15c32725e47ebfc)
diff --git a/msm8996/mm-video-v4l2/vidc/venc/inc/omx_video_base.h b/msm8996/mm-video-v4l2/vidc/venc/inc/omx_video_base.h
index fd88eca..1a537e4 100644
--- a/msm8996/mm-video-v4l2/vidc/venc/inc/omx_video_base.h
+++ b/msm8996/mm-video-v4l2/vidc/venc/inc/omx_video_base.h
@@ -1,5 +1,5 @@
 /*--------------------------------------------------------------------------
-Copyright (c) 2010-2016, The Linux Foundation. All rights reserved.
+Copyright (c) 2010-2017, The Linux Foundation. All rights reserved.
 
 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions are
@@ -649,6 +649,7 @@
         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/msm8996/mm-video-v4l2/vidc/venc/src/omx_video_base.cpp b/msm8996/mm-video-v4l2/vidc/venc/src/omx_video_base.cpp
index eeaf630..fa6b08f 100644
--- a/msm8996/mm-video-v4l2/vidc/venc/src/omx_video_base.cpp
+++ b/msm8996/mm-video-v4l2/vidc/venc/src/omx_video_base.cpp
@@ -1,5 +1,5 @@
 /*--------------------------------------------------------------------------
-Copyright (c) 2010-2016, Linux Foundation. All rights reserved.
+Copyright (c) 2010-2017, Linux Foundation. All rights reserved.
 
 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions are met:
@@ -314,6 +314,8 @@
     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);
 }
 
 
@@ -354,6 +356,8 @@
     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 ...");
 }
@@ -2594,6 +2598,7 @@
         return OMX_ErrorBadParameter;
     }
 
+    auto_lock l(m_buf_lock);
     if (!m_out_mem_ptr) {
         output_use_buffer = true;
         int nBufHdrSize        = 0;
@@ -3512,6 +3517,7 @@
                 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/msm8996/mm-video-v4l2/vidc/venc/src/omx_video_encoder.cpp b/msm8996/mm-video-v4l2/vidc/venc/src/omx_video_encoder.cpp
index 2591dc6..b09400a 100644
--- a/msm8996/mm-video-v4l2/vidc/venc/src/omx_video_encoder.cpp
+++ b/msm8996/mm-video-v4l2/vidc/venc/src/omx_video_encoder.cpp
@@ -2430,11 +2430,18 @@
                     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)) {
-                if (m_sVenc_msg->buf.len <=  omxhdr->nAllocLen) {
+                    (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;
                     omxhdr->nTimeStamp = m_sVenc_msg->buf.timestamp;
@@ -2459,6 +2466,7 @@
             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;