res_fax.c: crash on framehook with no dsp in fax detect

In fax_detect_framehook() a null pointer reference can occur where a
voice frame is processed but no dsp is attached to the fax detection
structure.  The code block that rejects frames that detection cannot
be processed on is checking for dsp but falls through when it should
instead return, as this change implements.

(closes issue ASTERISK-22942)
Reported by: adomjan
Review: https://reviewboard.asterisk.org/r/3076/

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/11@404351 65c4cc65-6c06-0410-ace0-fbb531ad65f3

diff --git a/res/res_fax.c b/res/res_fax.c
index bc07195eeb31f7fd524150cd767b1bdef4028234..073777a904d89838856917f25192a297871d5a91 100644 (file)
--- a/res/res_fax.c
+++ b/res/res_fax.c
@@ -3343,7 +3343,7 @@ static struct ast_frame *fax_detect_framehook(struct ast_channel *chan, struct a
        case AST_FRAME_VOICE:
                /* we have no DSP this means we not detecting CNG */
                if (!faxdetect->dsp) {
-                       break;
+                       return f;
                }
                /* We can only process some formats*/
                switch (f->subclass.format.id) {