[asterisk-commits] dvossel: branch 1.4 r228692 - /branches/1.4/main/channel.c

[SVN commits to the Asterisk project]

Author: dvossel
Date: Fri Nov  6 16:33:27 2009
New Revision: 228692

URL: http://svnview.digium.com/svn/asterisk?view=rev&rev=228692
Log:
fixes audiohook write crash occuring in chan_spy whisper mode.

After writing to the audiohook list in ast_write(), frames
were being freed incorrectly.  Under certain conditions this
resulted in a double free crash.

(closes issue #16133)
Reported by: wetwired

Modified:
    branches/1.4/main/channel.c

Modified: branches/1.4/main/channel.c
URL: http://svnview.digium.com/svn/asterisk/branches/1.4/main/channel.c?view=diff&rev=228692&r1=228691&r2=228692
==============================================================================
--- branches/1.4/main/channel.c (original)
+++ branches/1.4/main/channel.c Fri Nov  6 16:33:27 2009
@@ -2949,6 +2949,11 @@
 
 		if (chan->audiohooks) {
 			struct ast_frame *prev = NULL, *new_frame, *cur, *dup;
+			int freeoldlist = 0;
+
+			if (f != fr) {
+				freeoldlist = 1;
+			}
 
 			/* Since ast_audiohook_write may return a new frame, and the cur frame is
 			 * an item in a list of frames, create a new list adding each cur frame back to it
@@ -2959,13 +2964,16 @@
 				/* if this frame is different than cur, preserve the end of the list,
 				 * free the old frames, and set cur to be the new frame */
 				if (new_frame != cur) {
+
 					/* doing an ast_frisolate here seems silly, but we are not guaranteed the new_frame
 					 * isn't part of local storage, meaning if ast_audiohook_write is called multiple
 					 * times it may override the previous frame we got from it unless we dup it */
 					if ((dup = ast_frisolate(new_frame))) {
 						AST_LIST_NEXT(dup, frame_list) = AST_LIST_NEXT(cur, frame_list);
-						ast_frfree(new_frame);
-						ast_frfree(cur);
+						if (freeoldlist) {
+							AST_LIST_NEXT(cur, frame_list) = NULL;
+							ast_frfree(cur);
+						}
 						cur = dup;
 					}
 				}