From: Torrey Searle <torrey@voxbone.com>
Date: Thu, 29 Sep 2016 18:08:07 +0000 (+0200)
Subject: res_fax: Fix a tight race condition causing fax to crash in audio fallback
X-Git-Tag: 11.24.0-rc1~2^2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c0c041d9c7b3196344342adbda062046806e874a;p=thirdparty%2Fasterisk.git

res_fax: Fix a tight race condition causing fax to crash in audio fallback

When T.38 gets rejected and G711 failback occurs there is a period of
time where neither AST_FAX_TECH_T38 nor AST_FAX_TECH_AUDIO is set,
leading to a crash.

Change-Id: Icc3f457b2292d48a9d7843dac0028347420cc982
---

diff --git a/res/res_fax.c b/res/res_fax.c
index 833a3c8eec..0636540398 100644
--- a/res/res_fax.c
+++ b/res/res_fax.c
@@ -1344,6 +1344,13 @@ static int generic_fax_exec(struct ast_channel *chan, struct ast_fax_session_det
 	ast_format_clear(&orig_read_format);
 	chancount = 1;
 
+	/* Make sure one or the other is set to avoid race condition */
+	if (t38negotiated) {
+		details->caps |= AST_FAX_TECH_T38;
+	} else {
+		details->caps |= AST_FAX_TECH_AUDIO;
+	}
+
 	/* create the FAX session */
 	if (!(fax = fax_session_new(details, chan, reserved, token))) {
 		ast_log(LOG_ERROR, "Can't create a FAX session, FAX attempt failed.\n");