Merged revisions 114208 via svnmerge from

https://origsvn.digium.com/svn/asterisk/trunk

................
r114208 | mmichelson | 2008-04-17 11:40:12 -0500 (Thu, 17 Apr 2008) | 20 lines

Merged revisions 114207 via svnmerge from 
https://origsvn.digium.com/svn/asterisk/branches/1.4

........
r114207 | mmichelson | 2008-04-17 11:28:03 -0500 (Thu, 17 Apr 2008) | 12 lines

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


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git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.6.0@114210 65c4cc65-6c06-0410-ace0-fbb531ad65f3

include/asterisk/dsp.h

@@ -115,4 +115,16 @@ int ast_dsp_get_tstate(struct ast_dsp *dsp);
 /*! \brief Get tcount (Threshold counter) */
 int ast_dsp_get_tcount(struct ast_dsp *dsp);
 
+/*!
+ * \brief Hint that a frame from a dsp was freed
+ *
+ * This is called from ast_frame_free if AST_FRFLAG_FROM_DSP is set. This occurs
+ * because it is possible for the dsp to be freed while someone still holds a reference
+ * to the frame that is in that dsp. This has been known to happen when the dsp on a Zap
+ * channel detects a busy signal. The channel is hung up, and the application that read the
+ * frame to begin with still has a reference to the frame.
+ *
+ * \return nothing
+ */
+void ast_dsp_frame_freed(struct ast_frame *fr);
 #endif /* _ASTERISK_DSP_H */

include/asterisk/frame.h

@@ -130,6 +130,10 @@ 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

@@ -1241,6 +1241,7 @@ 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)) {
@@ -1250,6 +1251,7 @@ struct ast_frame *ast_dsp_process(struct ast_channel *chan, struct ast_dsp *dsp,
 		dsp->f.subclass = AST_CONTROL_BUSY;
 		ast_frfree(af);
 		ast_debug(1, "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) || (dsp->features & DSP_FEATURE_FAX_DETECT))) {
@@ -1271,6 +1273,7 @@ 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 {
@@ -1297,6 +1300,7 @@ 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));
@@ -1314,6 +1318,7 @@ 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;
 				}
 			}
@@ -1331,6 +1336,7 @@ 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;
 		}
 	}
@@ -1403,6 +1409,17 @@ 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 flag to destroy the dsp when the frame is freed */
+		dsp->freqcount = -1;
+
+		return;
+	}
 	ast_free(dsp);
 }
 
@@ -1516,3 +1533,17 @@ 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

@@ -37,6 +37,7 @@ ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
 #include "asterisk/threadstorage.h"
 #include "asterisk/linkedlists.h"
 #include "asterisk/translate.h"
+#include "asterisk/dsp.h"
 
 #ifdef TRACE_FRAMES
 static int headers;
@@ -308,6 +309,8 @@ 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;
@@ -357,6 +360,7 @@ 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 */