diff mbox series

[Bluez,v4] a2dp: Fix crash in channel_free while waiting cmd resp

Message ID 20210714170153.Bluez.v4.1.Id7aa1152377161d17b442bf258773d9b6c624ca3@changeid (mailing list archive)
State Accepted
Delegated to: Luiz Von Dentz
Headers show
Series [Bluez,v4] a2dp: Fix crash in channel_free while waiting cmd resp | expand

Commit Message

Howard Chung July 14, 2021, 9:02 a.m. UTC 
From: Yun-Hao Chung <howardchung@chromium.org>

When channel_free is called and we are waiting for a command response
from the peer, bluez NULL the setup->session but would not free its
setup_cb. Since setup_cb holds a ref of setup, the setup wouldn't be
freed and if service_removed is called after channel_free, a2dp_cancel
tries to abort the ongoing avdtp commands, which accesses the
setup->session and triggers a crash.

This change finalizes all avdtp commands before assigning setup->session
to NULL in channel_free.

Crash stack trace:
0x000059f01943e688	(bluetoothd -avdtp.c:3690)
avdtp_abort
0x000059f01943928a	(bluetoothd -a2dp.c:3069)
a2dp_cancel
0x000059f0194377fa	(bluetoothd -sink.c:324)
sink_unregister
0x000059f01948715a	(bluetoothd -service.c:177)
service_remove
0x000059f01948d77c	(bluetoothd -device.c:5346)
device_remove
0x000059f019476d14	(bluetoothd -adapter.c:7202)
adapter_remove
0x000059f019476c3e	(bluetoothd -adapter.c:10827)
adapter_cleanup
0x000059f01949d8d7	(bluetoothd -main.c:1114)		main
0x0000787b36185d74	(libc.so.6 -libc-start.c:308)
__libc_start_main
0x000059f019433e39	(bluetoothd + 0x00026e39)		_start
0x00007fff2d2c0127

Reviewed-by: Archie Pusaka <apusaka@chromium.org>
---
There are two other options to fix this crash.
1. add a NULL check in a2dp_cancel before calling avdtp_abort.
2. call setup_cb_free to every setup_cb in setup->cb in channel_free.

Since each setup_cb needs setup->session, I think there is no need to
keep the setup_cb after assigning setup->session to NULL. So the first
option is not ideal. If the second option is adopted, there would be
some time that sink/source->connect_id/disconnect_id is not zero, but
there is no corresponding setup_cb.

Test steps:
Reproduce the crash with the following steps. Verify the crash is
no longer observed after this change.
1. ignore AVDTP_SET_CONFIGURATION resp by modifying avdtp.c
2. turn on a paired headset
3. check the bluetooth.log, while bluez is waiting for
   AVDTP_SET_CONFIGURATION resp, stop bluetoothd immediately.
   This will trigger:
   session_cb (I/O error) -> connection_lost
   -> avdtp_set_state (AVDTP_SESSION_STATE_DISCONNECTED)
   -> avdtp_state_cb -> channel_remove -> channel_free
   then:
   adapter_cleanup -> adapter_remove -> device_remove -> service_remove
   -> a2dp_sink_remove -> sink_unregister -> sink_free -> a2dp_cancel
4. check if bluetoothd crash
The above steps can trigger the crash 100%.

Changes in v4:
- Fix compiling errors in finalize_all

Changes in v3:
- Remove the duplicated finalize_all

Changes in v2:
- Implement helper function finalize_all
- add setup_ref before finalize_all, in case the setup is freed during
  finalize

 profiles/audio/a2dp.c | 40 +++++++++++++++++++++++++++++++++++++++-
 1 file changed, 39 insertions(+), 1 deletion(-)

Comments

bluez.test.bot@gmail.com July 14, 2021, 9:36 a.m. UTC | #1 
This is automated email and please do not reply to this email!

Dear submitter,

Thank you for submitting the patches to the linux bluetooth mailing list.
This is a CI test results with your patch series:
PW Link:https://patchwork.kernel.org/project/bluetooth/list/?series=515283

---Test result---

Test Summary:
CheckPatch                    PASS      0.34 seconds
GitLint                       FAIL      0.09 seconds
Prep - Setup ELL              PASS      37.99 seconds
Build - Prep                  PASS      0.10 seconds
Build - Configure             PASS      6.53 seconds
Build - Make                  PASS      165.22 seconds
Make Check                    PASS      9.22 seconds
Make Distcheck                PASS      193.33 seconds
Build w/ext ELL - Configure   PASS      6.37 seconds
Build w/ext ELL - Make        PASS      153.23 seconds

Details
##############################
Test: CheckPatch - PASS
Desc: Run checkpatch.pl script with rule in .checkpatch.conf

##############################
Test: GitLint - FAIL
Desc: Run gitlint with rule in .gitlint
Output:
a2dp: Fix crash in channel_free while waiting cmd resp
14: B3 Line contains hard tab characters (\t): "0x000059f01943e688	(bluetoothd -avdtp.c:3690)"
16: B3 Line contains hard tab characters (\t): "0x000059f01943928a	(bluetoothd -a2dp.c:3069)"
18: B3 Line contains hard tab characters (\t): "0x000059f0194377fa	(bluetoothd -sink.c:324)"
20: B3 Line contains hard tab characters (\t): "0x000059f01948715a	(bluetoothd -service.c:177)"
22: B3 Line contains hard tab characters (\t): "0x000059f01948d77c	(bluetoothd -device.c:5346)"
24: B3 Line contains hard tab characters (\t): "0x000059f019476d14	(bluetoothd -adapter.c:7202)"
26: B3 Line contains hard tab characters (\t): "0x000059f019476c3e	(bluetoothd -adapter.c:10827)"
28: B3 Line contains hard tab characters (\t): "0x000059f01949d8d7	(bluetoothd -main.c:1114)		main"
29: B3 Line contains hard tab characters (\t): "0x0000787b36185d74	(libc.so.6 -libc-start.c:308)"
31: B3 Line contains hard tab characters (\t): "0x000059f019433e39	(bluetoothd + 0x00026e39)		_start"


##############################
Test: Prep - Setup ELL - PASS
Desc: Clone, build, and install ELL

##############################
Test: Build - Prep - PASS
Desc: Prepare environment for build

##############################
Test: Build - Configure - PASS
Desc: Configure the BlueZ source tree

##############################
Test: Build - Make - PASS
Desc: Build the BlueZ source tree

##############################
Test: Make Check - PASS
Desc: Run 'make check'

##############################
Test: Make Distcheck - PASS
Desc: Run distcheck to check the distribution

##############################
Test: Build w/ext ELL - Configure - PASS
Desc: Configure BlueZ source with '--enable-external-ell' configuration

##############################
Test: Build w/ext ELL - Make - PASS
Desc: Build BlueZ source with '--enable-external-ell' configuration



---
Regards,
Linux Bluetooth
Luiz Augusto von Dentz July 14, 2021, 6:41 p.m. UTC | #2 
Hi Howard,

On Wed, Jul 14, 2021 at 2:38 AM <bluez.test.bot@gmail.com> wrote:
>
> This is automated email and please do not reply to this email!
>
> Dear submitter,
>
> Thank you for submitting the patches to the linux bluetooth mailing list.
> This is a CI test results with your patch series:
> PW Link:https://patchwork.kernel.org/project/bluetooth/list/?series=515283
>
> ---Test result---
>
> Test Summary:
> CheckPatch                    PASS      0.34 seconds
> GitLint                       FAIL      0.09 seconds
> Prep - Setup ELL              PASS      37.99 seconds
> Build - Prep                  PASS      0.10 seconds
> Build - Configure             PASS      6.53 seconds
> Build - Make                  PASS      165.22 seconds
> Make Check                    PASS      9.22 seconds
> Make Distcheck                PASS      193.33 seconds
> Build w/ext ELL - Configure   PASS      6.37 seconds
> Build w/ext ELL - Make        PASS      153.23 seconds
>
> Details
> ##############################
> Test: CheckPatch - PASS
> Desc: Run checkpatch.pl script with rule in .checkpatch.conf
>
> ##############################
> Test: GitLint - FAIL
> Desc: Run gitlint with rule in .gitlint
> Output:
> a2dp: Fix crash in channel_free while waiting cmd resp
> 14: B3 Line contains hard tab characters (\t): "0x000059f01943e688      (bluetoothd -avdtp.c:3690)"
> 16: B3 Line contains hard tab characters (\t): "0x000059f01943928a      (bluetoothd -a2dp.c:3069)"
> 18: B3 Line contains hard tab characters (\t): "0x000059f0194377fa      (bluetoothd -sink.c:324)"
> 20: B3 Line contains hard tab characters (\t): "0x000059f01948715a      (bluetoothd -service.c:177)"
> 22: B3 Line contains hard tab characters (\t): "0x000059f01948d77c      (bluetoothd -device.c:5346)"
> 24: B3 Line contains hard tab characters (\t): "0x000059f019476d14      (bluetoothd -adapter.c:7202)"
> 26: B3 Line contains hard tab characters (\t): "0x000059f019476c3e      (bluetoothd -adapter.c:10827)"
> 28: B3 Line contains hard tab characters (\t): "0x000059f01949d8d7      (bluetoothd -main.c:1114)               main"
> 29: B3 Line contains hard tab characters (\t): "0x0000787b36185d74      (libc.so.6 -libc-start.c:308)"
> 31: B3 Line contains hard tab characters (\t): "0x000059f019433e39      (bluetoothd + 0x00026e39)               _start"
>
>
> ##############################
> Test: Prep - Setup ELL - PASS
> Desc: Clone, build, and install ELL
>
> ##############################
> Test: Build - Prep - PASS
> Desc: Prepare environment for build
>
> ##############################
> Test: Build - Configure - PASS
> Desc: Configure the BlueZ source tree
>
> ##############################
> Test: Build - Make - PASS
> Desc: Build the BlueZ source tree
>
> ##############################
> Test: Make Check - PASS
> Desc: Run 'make check'
>
> ##############################
> Test: Make Distcheck - PASS
> Desc: Run distcheck to check the distribution
>
> ##############################
> Test: Build w/ext ELL - Configure - PASS
> Desc: Configure BlueZ source with '--enable-external-ell' configuration
>
> ##############################
> Test: Build w/ext ELL - Make - PASS
> Desc: Build BlueZ source with '--enable-external-ell' configuration
>
>
>
> ---
> Regards,
> Linux Bluetooth

Applied, thanks.
diff mbox series

Patch

diff --git a/profiles/audio/a2dp.c b/profiles/audio/a2dp.c
index d31ed845cbe7..86bc02994f75 100644
--- a/profiles/audio/a2dp.c
+++ b/profiles/audio/a2dp.c
@@ -404,6 +404,41 @@  static void finalize_discover(struct a2dp_setup *s)
 	}
 }
 
+static gboolean finalize_all(gpointer data)
+{
+	struct a2dp_setup *s = data;
+	struct avdtp_stream *stream = s->err ? NULL : s->stream;
+	GSList *l;
+
+	for (l = s->cb; l != NULL; ) {
+		struct a2dp_setup_cb *cb = l->data;
+
+		l = l->next;
+
+		if (cb->discover_cb) {
+			cb->discover_cb(s->session, s->seps,
+					error_to_errno(s->err), cb->user_data);
+		} else if (cb->select_cb) {
+			cb->select_cb(s->session, s->sep, s->caps,
+					error_to_errno(s->err), cb->user_data);
+		} else if (cb->suspend_cb) {
+			cb->suspend_cb(s->session,
+					error_to_errno(s->err), cb->user_data);
+		} else if (cb->resume_cb) {
+			cb->resume_cb(s->session,
+					error_to_errno(s->err), cb->user_data);
+		} else if (cb->config_cb) {
+			cb->config_cb(s->session, s->sep, stream,
+					error_to_errno(s->err), cb->user_data);
+		} else
+			warn("setup_cb doesn't have any callback function");
+
+		setup_cb_free(cb);
+	}
+
+	return FALSE;
+}
+
 static struct a2dp_setup *find_setup_by_session(struct avdtp *session)
 {
 	GSList *l;
@@ -1540,9 +1575,12 @@  static void channel_free(void *data)
 	setup = find_setup_by_session(chan->session);
 	if (setup) {
 		setup->chan = NULL;
+		setup_ref(setup);
+		/* Finalize pending commands before we NULL setup->session */
+		finalize_setup_errno(setup, -ENOTCONN, finalize_all, NULL);
 		avdtp_unref(setup->session);
 		setup->session = NULL;
-		finalize_setup_errno(setup, -ENOTCONN, NULL);
+		setup_unref(setup);
 	}
 
 	g_free(chan);