It was possible for a reference to a frame which was part of a freed DSP to still be

referenced, leading to memory corruption and eventual crashes. This code change ensures
that the dsp is freed when we are finished with the frame. This change is very similar
to a change Russell made with translators back a month or so ago.

(closes issue #11999)
Reported by: destiny6628
Patches:
      11999.patch uploaded by putnopvut (license 60)
Tested by: destiny6628, victoryure



git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@114207 65c4cc65-6c06-0410-ace0-fbb531ad65f3

include/asterisk/frame.h

@@ -131,6 +131,10 @@ enum {
 	 *  The translator can not be free'd if the frame inside of it still has
 	 *  this flag set. */
 	AST_FRFLAG_FROM_TRANSLATOR = (1 << 1),
+	/*! This frame came from a dsp and is still the original frame.
+	 *  The dsp cannot be free'd if the frame inside of it still has
+	 *  this flag set. */
+	AST_FRFLAG_FROM_DSP = (1 << 2),
 };
 
 /*! \brief Data structure associated with a single frame of data

main/dsp.c

@@ -1486,6 +1486,7 @@ struct ast_frame *ast_dsp_process(struct ast_channel *chan, struct ast_dsp *dsp,
 		memset(&dsp->f, 0, sizeof(dsp->f));
 		dsp->f.frametype = AST_FRAME_NULL;
 		ast_frfree(af);
+		ast_set_flag(&dsp->f, AST_FRFLAG_FROM_DSP);
 		return &dsp->f;
 	}
 	if ((dsp->features & DSP_FEATURE_BUSY_DETECT) && ast_dsp_busydetect(dsp)) {
@@ -1494,7 +1495,7 @@ struct ast_frame *ast_dsp_process(struct ast_channel *chan, struct ast_dsp *dsp,
 		dsp->f.frametype = AST_FRAME_CONTROL;
 		dsp->f.subclass = AST_CONTROL_BUSY;
 		ast_frfree(af);
-		ast_log(LOG_DEBUG, "Requesting Hangup because the busy tone was detected on channel %s\n", chan->name);
+		ast_set_flag(&dsp->f, AST_FRFLAG_FROM_DSP);
 		return &dsp->f;
 	}
 	if ((dsp->features & DSP_FEATURE_DTMF_DETECT)) {
@@ -1516,6 +1517,7 @@ struct ast_frame *ast_dsp_process(struct ast_channel *chan, struct ast_dsp *dsp,
 					if (chan)
 						ast_queue_frame(chan, af);
 					ast_frfree(af);
+					ast_set_flag(&dsp->f, AST_FRFLAG_FROM_DSP);
 					return &dsp->f;
 				}
 			} else {
@@ -1542,6 +1544,7 @@ struct ast_frame *ast_dsp_process(struct ast_channel *chan, struct ast_dsp *dsp,
 							ast_queue_frame(chan, af);
 						ast_frfree(af);
 					}
+					ast_set_flag(&dsp->f, AST_FRFLAG_FROM_DSP);
 					return &dsp->f;
 				} else {
 					memset(&dsp->f, 0, sizeof(dsp->f));
@@ -1559,6 +1562,7 @@ struct ast_frame *ast_dsp_process(struct ast_channel *chan, struct ast_dsp *dsp,
 					if (chan)
 						ast_queue_frame(chan, af);
 					ast_frfree(af);
+					ast_set_flag(&dsp->f, AST_FRFLAG_FROM_DSP);
 					return &dsp->f;
 				}
 			}
@@ -1575,6 +1579,7 @@ struct ast_frame *ast_dsp_process(struct ast_channel *chan, struct ast_dsp *dsp,
 					if (chan)
 						ast_queue_frame(chan, af);
 					ast_frfree(af);
+					ast_set_flag(&dsp->f, AST_FRFLAG_FROM_DSP);
 					return &dsp->f;
 				}
 			} else {
@@ -1588,6 +1593,7 @@ struct ast_frame *ast_dsp_process(struct ast_channel *chan, struct ast_dsp *dsp,
 					if (chan)
 						ast_queue_frame(chan, af);
 					ast_frfree(af);
+					ast_set_flag(&dsp->f, AST_FRFLAG_FROM_DSP);
 					return &dsp->f;
 				}
 			}
@@ -1658,6 +1664,17 @@ void ast_dsp_set_features(struct ast_dsp *dsp, int features)
 
 void ast_dsp_free(struct ast_dsp *dsp)
 {
+	if (ast_test_flag(&dsp->f, AST_FRFLAG_FROM_DSP)) {
+		/* If this flag is still set, that means that the dsp's destruction 
+		 * been torn down, while we still have a frame out there being used.
+		 * When ast_frfree() gets called on that frame, this ast_trans_pvt
+		 * will get destroyed, too. */
+
+		/* Set the magic hint that this has been requested to be destroyed. */
+		dsp->freqcount = -1;
+
+		return;
+	}
 	free(dsp);
 }
 
@@ -1786,3 +1803,17 @@ int ast_dsp_get_tcount(struct ast_dsp *dsp)
 {
 	return dsp->tcount;
 }
+
+void ast_dsp_frame_freed(struct ast_frame *fr)
+{
+	struct ast_dsp *dsp;
+
+	ast_clear_flag(fr, AST_FRFLAG_FROM_DSP);
+
+	dsp = (struct ast_dsp *) (((char *) fr) - offsetof(struct ast_dsp, f));
+
+	if (dsp->freqcount != -1)
+		return;
+	
+	ast_dsp_free(dsp);
+}

main/frame.c

@@ -321,6 +321,8 @@ void ast_frame_free(struct ast_frame *fr, int cache)
 {
 	if (ast_test_flag(fr, AST_FRFLAG_FROM_TRANSLATOR))
 		ast_translate_frame_freed(fr);
+	else if (ast_test_flag(fr, AST_FRFLAG_FROM_DSP))
+		ast_dsp_frame_freed(fr);
 
 	if (!fr->mallocd)
 		return;
@@ -370,6 +372,7 @@ struct ast_frame *ast_frisolate(struct ast_frame *fr)
 	void *newdata;
 
 	ast_clear_flag(fr, AST_FRFLAG_FROM_TRANSLATOR);
+	ast_clear_flag(fr, AST_FRFLAG_FROM_DSP);
 
 	if (!(fr->mallocd & AST_MALLOCD_HDR)) {
 		/* Allocate a new header if needed */