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res_fax.c: Fix deadlock potential in FAXOPT(faxdetect) framehook.

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The fax_detect_framehook() has the potential to deadlock if an incoming
fax happens during the Playback or similar application.

* Fixed the potential deadlock by not calling ast_async_goto() with the
channel lock held.

* Made always eat the fax detection frame whether there is a fax extension
or not.

* Made only detach the framehook if we detected a fax and not on other
possible frames.

ASTERISK-26216
Reported by: Richard Mudgett

Change-Id: I99da35c26d1cd802626ffb4c1b4eb5b015581b6d
This commit is contained in:
Richard Mudgett
2016-07-12 17:33:29 -05:00
parent 943bb48b59
commit 9abbea162c
1 changed files with 13 additions and 7 deletions
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20
res/res_fax.c
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@@ -3701,30 +3701,36 @@ static struct ast_frame *fax_detect_framehook(struct ast_channel *chan, struct a
}
if (result) {
const char *target_context = S_OR(ast_channel_macrocontext(chan), ast_channel_context(chan));
const char *target_context;
switch (result) {
case 'f':
case 't':
target_context = S_OR(ast_channel_macrocontext(chan), ast_channel_context(chan));
ast_channel_unlock(chan);
ast_frfree(f);
f = &ast_null_frame;
if (ast_exists_extension(chan, target_context, "fax", 1,
S_COR(ast_channel_caller(chan)->id.number.valid, ast_channel_caller(chan)->id.number.str, NULL))) {
ast_channel_lock(chan);
ast_verb(2, "Redirecting '%s' to fax extension due to %s detection\n",
ast_channel_name(chan), (result == 'f') ? "CNG" : "T38");
pbx_builtin_setvar_helper(chan, "FAXEXTEN", ast_channel_exten(chan));
if (ast_async_goto(chan, target_context, "fax", 1)) {
ast_log(LOG_NOTICE, "Failed to async goto '%s' into fax of '%s'\n", ast_channel_name(chan), target_context);
}
ast_frfree(f);
f = &ast_null_frame;
} else {
ast_channel_lock(chan);
ast_log(LOG_NOTICE, "FAX %s detected but no fax extension in context (%s)\n",
(result == 'f') ? "CNG" : "T38", target_context);
}
ast_channel_lock(chan);
ast_framehook_detach(chan, details->faxdetect_id);
details->faxdetect_id = -1;
break;
default:
break;
}
ast_framehook_detach(chan, details->faxdetect_id);
details->faxdetect_id = -1;
}
return f;