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res_musiconhold: avoid moh state access on unlocked chan 

Move channel unlock to after moh state access to avoid
potential unlocked access to state.

Resolves: #133
(cherry picked from commit 9c889911ad)
This commit is contained in:
Mike Bradeen 2023-05-31 10:37:53 -06:00 committed by Asterisk Development Team
parent 714950bd7c
commit 9dbd80ab73
1 changed files with 22 additions and 11 deletions
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33
res/res_musiconhold.c
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@ -464,24 +464,22 @@ static void moh_files_write_format_change(struct ast_channel *chan, void *data)
static int moh_files_generator(struct ast_channel *chan, void *data, int len, int samples)
{
struct moh_files_state *state = ast_channel_music_state(chan);
struct moh_files_state *state;
struct ast_frame *f = NULL;
int res = 0;
int res = 0, sample_queue = 0;
ast_channel_lock(chan);
state = ast_channel_music_state(chan);
state->sample_queue += samples;
/* save the sample queue value for un-locked access */
sample_queue = state->sample_queue;
ast_channel_unlock(chan);
while (state->sample_queue > 0) {
while (sample_queue > 0) {
ast_channel_lock(chan);
f = moh_files_readframe(chan);
/* We need to be sure that we unlock
* the channel prior to calling
* ast_write. Otherwise, the recursive locking
* that occurs can cause deadlocks when using
* indirect channels, like local channels
*/
ast_channel_unlock(chan);
if (!f) {
ast_channel_unlock(chan);
return -1;
}
@ -495,6 +493,19 @@ static int moh_files_generator(struct ast_channel *chan, void *data, int len, in
if (ast_format_cmp(f->subclass.format, state->mohwfmt) == AST_FORMAT_CMP_NOT_EQUAL) {
ao2_replace(state->mohwfmt, f->subclass.format);
}
/* We need to be sure that we unlock
* the channel prior to calling
* ast_write, but after our references to state
* as it refers to chan->music_state. Update
* sample_queue for our loop
* Otherwise, the recursive locking that occurs
* can cause deadlocks when using indirect
* channels, like local channels
*/
sample_queue = state->sample_queue;
ast_channel_unlock(chan);
res = ast_write(chan, f);
ast_frfree(f);
if (res < 0) {