<p>Friendly Automation <strong>merged</strong> this change.</p><p><a href="https://gerrit.asterisk.org/10601">View Change</a></p><div style="white-space:pre-wrap">Approvals:
George Joseph: Looks good to me, but someone else must approve
Joshua C. Colp: Looks good to me, approved
Friendly Automation: Approved for Submit
</div><pre style="font-family: monospace,monospace; white-space: pre-wrap;">res/res_pjsip: Fix crash due to misuse of session->media between threads.<br><br>This patch makes sure that thread running ast_taskprocessor_execute<br>cannot suddenly dispose the session->media object making the other<br>threads (running pbx_thread / bridge_channel_ind_thread) crash when they<br>try to access the pointer to invalid memory. We were experiencing a crash due<br>to a misuse of session->media container between threads running<br>(bridge_channel_ind_thread/pbx_thread) and the thread running<br>ast_taskprocessor_execute. Depending on the SIP flow (during a disconnection)<br>and the threads' code path, the session->media container was being destroyed<br>(and set to NULL) by the thread running ast_taskprocessor_execute while the<br>thread running t38_framehook_read was still referring to it.<br>Now res_pjsip_t38 is referring a session_media in a datastore.<br><br>ASTERISK-28156<br><br>Change-Id: Ia92e2389b8d804bf205473e92ec06217e87ce237<br>---<br>M res/res_pjsip_t38.c<br>1 file changed, 51 insertions(+), 12 deletions(-)<br><br></pre><pre style="font-family: monospace,monospace; white-space: pre-wrap;"><span>diff --git a/res/res_pjsip_t38.c b/res/res_pjsip_t38.c</span><br><span>index cff625f..cd225d4 100644</span><br><span>--- a/res/res_pjsip_t38.c</span><br><span>+++ b/res/res_pjsip_t38.c</span><br><span>@@ -79,6 +79,17 @@</span><br><span> .destroy = t38_state_destroy,</span><br><span> };</span><br><span> </span><br><span style="color: hsl(120, 100%, 40%);">+static void session_media_dec(void *obj)</span><br><span style="color: hsl(120, 100%, 40%);">+{</span><br><span style="color: hsl(120, 100%, 40%);">+ ao2_cleanup(obj);</span><br><span style="color: hsl(120, 100%, 40%);">+}</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+/*! \brief Datastore for T.38 session_media information */</span><br><span style="color: hsl(120, 100%, 40%);">+static const struct ast_datastore_info session_media_datastore = {</span><br><span style="color: hsl(120, 100%, 40%);">+ .type = "t38_session_media",</span><br><span style="color: hsl(120, 100%, 40%);">+ .destroy = session_media_dec,</span><br><span style="color: hsl(120, 100%, 40%);">+};</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span> /*! \brief Structure for T.38 parameters task data */</span><br><span> struct t38_parameters_task_data {</span><br><span> /*! \brief Session itself */</span><br><span>@@ -120,6 +131,36 @@</span><br><span> return data;</span><br><span> }</span><br><span> </span><br><span style="color: hsl(120, 100%, 40%);">+/*! \brief Helper function which retrieves a T.38 session_media from datastore */</span><br><span style="color: hsl(120, 100%, 40%);">+static struct ast_sip_session_media *session_media_from_datastore_addref(struct ast_sip_session *session)</span><br><span style="color: hsl(120, 100%, 40%);">+{</span><br><span style="color: hsl(120, 100%, 40%);">+ struct ast_datastore *datastore = NULL;</span><br><span style="color: hsl(120, 100%, 40%);">+ struct ast_sip_session_media *session_media = NULL;</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ if ((datastore = ast_sip_session_get_datastore(session, "t38_session_media"))) {</span><br><span style="color: hsl(120, 100%, 40%);">+ session_media = datastore->data;</span><br><span style="color: hsl(120, 100%, 40%);">+ ao2_ref(session_media, +1);</span><br><span style="color: hsl(120, 100%, 40%);">+ ao2_ref(datastore, -1);</span><br><span style="color: hsl(120, 100%, 40%);">+ }</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ return session_media;</span><br><span style="color: hsl(120, 100%, 40%);">+}</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+/*! \brief Helper function which allocates datastore with a session media */</span><br><span style="color: hsl(120, 100%, 40%);">+static struct ast_datastore *create_datastore_session_media(struct ast_sip_session *session, struct ast_sip_session_media *session_media)</span><br><span style="color: hsl(120, 100%, 40%);">+{</span><br><span style="color: hsl(120, 100%, 40%);">+ struct ast_datastore *datastore = NULL;</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ if (!(datastore = ast_sip_session_alloc_datastore(&session_media_datastore, "t38_session_media"))</span><br><span style="color: hsl(120, 100%, 40%);">+ || ast_sip_session_add_datastore(session, datastore)) {</span><br><span style="color: hsl(120, 100%, 40%);">+ return NULL;</span><br><span style="color: hsl(120, 100%, 40%);">+ }</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ datastore->data = session_media;</span><br><span style="color: hsl(120, 100%, 40%);">+ ao2_bump(session_media);</span><br><span style="color: hsl(120, 100%, 40%);">+ return datastore;</span><br><span style="color: hsl(120, 100%, 40%);">+}</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span> /*! \brief Helper function for changing the T.38 state */</span><br><span> static void t38_change_state(struct ast_sip_session *session, struct ast_sip_session_media *session_media,</span><br><span> struct t38_state *state, enum ast_sip_session_t38state new_state)</span><br><span>@@ -198,7 +239,7 @@</span><br><span> {</span><br><span> RAII_VAR(struct ast_sip_session *, session, obj, ao2_cleanup);</span><br><span> RAII_VAR(struct ast_datastore *, datastore, ast_sip_session_get_datastore(session, "t38"), ao2_cleanup);</span><br><span style="color: hsl(0, 100%, 40%);">- RAII_VAR(struct ast_sip_session_media *, session_media, ao2_find(session->media, "image", OBJ_KEY), ao2_cleanup);</span><br><span style="color: hsl(120, 100%, 40%);">+ RAII_VAR(struct ast_sip_session_media *, session_media, session_media_from_datastore_addref(session), ao2_cleanup);</span><br><span> </span><br><span> if (!datastore) {</span><br><span> return 0;</span><br><span>@@ -255,6 +296,10 @@</span><br><span> return 0;</span><br><span> }</span><br><span> </span><br><span style="color: hsl(120, 100%, 40%);">+ if (!create_datastore_session_media(session, session_media)) {</span><br><span style="color: hsl(120, 100%, 40%);">+ return -1;</span><br><span style="color: hsl(120, 100%, 40%);">+ }</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span> if (!(session_media->udptl = ast_udptl_new_with_bindaddr(NULL, NULL, 0, &address))) {</span><br><span> return -1;</span><br><span> }</span><br><span>@@ -292,7 +337,8 @@</span><br><span> {</span><br><span> struct pjsip_status_line status = rdata->msg_info.msg->line.status;</span><br><span> struct t38_state *state;</span><br><span style="color: hsl(0, 100%, 40%);">- struct ast_sip_session_media *session_media = NULL;</span><br><span style="color: hsl(120, 100%, 40%);">+ RAII_VAR(struct ast_sip_session_media *, session_media,</span><br><span style="color: hsl(120, 100%, 40%);">+ session_media_from_datastore_addref(session), ao2_cleanup);</span><br><span> </span><br><span> if (status.code / 100 <= 1) {</span><br><span> /* Ignore any non-final responses (1xx) */</span><br><span>@@ -300,7 +346,7 @@</span><br><span> }</span><br><span> </span><br><span> if (!session->channel || !(state = t38_state_get_or_alloc(session)) ||</span><br><span style="color: hsl(0, 100%, 40%);">- !(session_media = ao2_find(session->media, "image", OBJ_KEY))) {</span><br><span style="color: hsl(120, 100%, 40%);">+ !session_media) {</span><br><span> ast_log(LOG_WARNING, "Received %d response to T.38 re-invite on '%s' but state unavailable\n",</span><br><span> status.code,</span><br><span> session->channel ? ast_channel_name(session->channel) : "unknown channel");</span><br><span>@@ -311,7 +357,6 @@</span><br><span> t38_change_state(session, session_media, state,</span><br><span> (status.code / 100 == 2) ? T38_ENABLED : T38_REJECTED);</span><br><span> </span><br><span style="color: hsl(0, 100%, 40%);">- ao2_cleanup(session_media);</span><br><span> return 0;</span><br><span> }</span><br><span> </span><br><span>@@ -446,10 +491,7 @@</span><br><span> } else if (f->frametype == AST_FRAME_MODEM) {</span><br><span> struct ast_sip_session_media *session_media;</span><br><span> </span><br><span style="color: hsl(0, 100%, 40%);">- /* Avoid deadlock between chan and the session->media container lock */</span><br><span style="color: hsl(0, 100%, 40%);">- ast_channel_unlock(chan);</span><br><span style="color: hsl(0, 100%, 40%);">- session_media = ao2_find(session->media, "image", OBJ_SEARCH_KEY);</span><br><span style="color: hsl(0, 100%, 40%);">- ast_channel_lock(chan);</span><br><span style="color: hsl(120, 100%, 40%);">+ session_media = session_media_from_datastore_addref(session);</span><br><span> if (session_media && session_media->udptl) {</span><br><span> ast_udptl_write(session_media->udptl, f);</span><br><span> }</span><br><span>@@ -466,10 +508,7 @@</span><br><span> if (ast_channel_fdno(session->channel) == 5) {</span><br><span> struct ast_sip_session_media *session_media;</span><br><span> </span><br><span style="color: hsl(0, 100%, 40%);">- /* Avoid deadlock between chan and the session->media container lock */</span><br><span style="color: hsl(0, 100%, 40%);">- ast_channel_unlock(chan);</span><br><span style="color: hsl(0, 100%, 40%);">- session_media = ao2_find(session->media, "image", OBJ_SEARCH_KEY);</span><br><span style="color: hsl(0, 100%, 40%);">- ast_channel_lock(chan);</span><br><span style="color: hsl(120, 100%, 40%);">+ session_media = session_media_from_datastore_addref(session);</span><br><span> if (session_media && session_media->udptl) {</span><br><span> f = ast_udptl_read(session_media->udptl);</span><br><span> }</span><br><span></span><br></pre><p>To view, visit <a href="https://gerrit.asterisk.org/10601">change 10601</a>. 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<div style="display:none"> Gerrit-Project: asterisk </div>
<div style="display:none"> Gerrit-Branch: 13 </div>
<div style="display:none"> Gerrit-MessageType: merged </div>
<div style="display:none"> Gerrit-Change-Id: Ia92e2389b8d804bf205473e92ec06217e87ce237 </div>
<div style="display:none"> Gerrit-Change-Number: 10601 </div>
<div style="display:none"> Gerrit-PatchSet: 7 </div>
<div style="display:none"> Gerrit-Owner: Paulo Vicentini <paulo.vicentini@gmail.com> </div>
<div style="display:none"> Gerrit-Reviewer: Friendly Automation (1000185) </div>
<div style="display:none"> Gerrit-Reviewer: George Joseph <gjoseph@digium.com> </div>
<div style="display:none"> Gerrit-Reviewer: Joshua C. Colp <jcolp@digium.com> </div>
<div style="display:none"> Gerrit-Reviewer: Matthew Fredrickson <creslin@digium.com> </div>
<div style="display:none"> Gerrit-Reviewer: Paulo Vicentini <paulo.vicentini@gmail.com> </div>
<div style="display:none"> Gerrit-Reviewer: Torrey Searle <tsearle@gmail.com> </div>