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* [Bluez PATCH v3] a2dp: Fix crash in channel_free while waiting cmd resp
@ 2021-07-13  9:55 Howard Chung
  2021-07-13 10:38 ` [Bluez,v3] " bluez.test.bot
  0 siblings, 1 reply; 2+ messages in thread
From: Howard Chung @ 2021-07-13  9:55 UTC (permalink / raw)
  To: linux-bluetooth, luiz.dentz; +Cc: Yun-Hao Chung, Archie Pusaka

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 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 | 37 ++++++++++++++++++++++++++++++++++++-
 1 file changed, 36 insertions(+), 1 deletion(-)

diff --git a/profiles/audio/a2dp.c b/profiles/audio/a2dp.c
index d31ed845cbe7..39d5e3ef736c 100644
--- a/profiles/audio/a2dp.c
+++ b/profiles/audio/a2dp.c
@@ -404,6 +404,38 @@ static void finalize_discover(struct a2dp_setup *s)
 	}
 }
 
+static void finalize_all(struct a2dp_setup *s)
+{
+	GSList *l;
+	struct avdtp_stream *stream = s->err ? NULL : s->stream;
+
+	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->seps, 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->seps, stream,
+					error_to_errno(s->err), cb->user_data);
+		} else
+			warn("setup_cb doesn't have any callback function");
+
+		setup_cb_free(cb);
+	}
+}
+
 static struct a2dp_setup *find_setup_by_session(struct avdtp *session)
 {
 	GSList *l;
@@ -1540,9 +1572,12 @@ 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);
-- 
2.32.0.93.g670b81a890-goog


^ permalink raw reply	[flat|nested] 2+ messages in thread

* RE: [Bluez,v3] a2dp: Fix crash in channel_free while waiting cmd resp
  2021-07-13  9:55 [Bluez PATCH v3] a2dp: Fix crash in channel_free while waiting cmd resp Howard Chung
@ 2021-07-13 10:38 ` bluez.test.bot
  0 siblings, 0 replies; 2+ messages in thread
From: bluez.test.bot @ 2021-07-13 10:38 UTC (permalink / raw)
  To: linux-bluetooth, howardchung

[-- Attachment #1: Type: text/plain, Size: 8659 bytes --]

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=514653

---Test result---

Test Summary:
CheckPatch                    PASS      0.39 seconds
GitLint                       FAIL      0.13 seconds
Prep - Setup ELL              PASS      48.01 seconds
Build - Prep                  PASS      0.11 seconds
Build - Configure             PASS      8.45 seconds
Build - Make                  FAIL      156.82 seconds
Make Check                    FAIL      1.34 seconds
Make Distcheck                PASS      241.40 seconds
Build w/ext ELL - Configure   PASS      8.29 seconds
Build w/ext ELL - Make        FAIL      144.34 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 - FAIL
Desc: Build the BlueZ source tree
Output:
profiles/audio/a2dp.c: In function ‘finalize_all’:
profiles/audio/a2dp.c:421:31: error: passing argument 2 of ‘cb->select_cb’ from incompatible pointer type [-Werror=incompatible-pointer-types]
  421 |    cb->select_cb(s->session, s->seps, s->caps,
      |                              ~^~~~~~
      |                               |
      |                               GSList * {aka struct _GSList *}
profiles/audio/a2dp.c:421:31: note: expected ‘struct a2dp_sep *’ but argument is of type ‘GSList *’ {aka ‘struct _GSList *’}
profiles/audio/a2dp.c:430:31: error: passing argument 2 of ‘cb->config_cb’ from incompatible pointer type [-Werror=incompatible-pointer-types]
  430 |    cb->config_cb(s->session, s->seps, stream,
      |                              ~^~~~~~
      |                               |
      |                               GSList * {aka struct _GSList *}
profiles/audio/a2dp.c:430:31: note: expected ‘struct a2dp_sep *’ but argument is of type ‘GSList *’ {aka ‘struct _GSList *’}
profiles/audio/a2dp.c: In function ‘channel_free’:
profiles/audio/a2dp.c:1577:42: error: passing argument 3 of ‘finalize_setup_errno’ from incompatible pointer type [-Werror=incompatible-pointer-types]
 1577 |   finalize_setup_errno(setup, -ENOTCONN, finalize_all, NULL);
      |                                          ^~~~~~~~~~~~
      |                                          |
      |                                          void (*)(struct a2dp_setup *)
profiles/audio/a2dp.c:262:18: note: expected ‘GSourceFunc’ {aka ‘int (*)(void *)’} but argument is of type ‘void (*)(struct a2dp_setup *)’
  262 |      GSourceFunc cb1, ...)
      |      ~~~~~~~~~~~~^~~
cc1: all warnings being treated as errors
make[1]: *** [Makefile:8531: profiles/audio/bluetoothd-a2dp.o] Error 1
make: *** [Makefile:4134: all] Error 2


##############################
Test: Make Check - FAIL
Desc: Run 'make check'
Output:
profiles/audio/a2dp.c: In function ‘finalize_all’:
profiles/audio/a2dp.c:421:31: error: passing argument 2 of ‘cb->select_cb’ from incompatible pointer type [-Werror=incompatible-pointer-types]
  421 |    cb->select_cb(s->session, s->seps, s->caps,
      |                              ~^~~~~~
      |                               |
      |                               GSList * {aka struct _GSList *}
profiles/audio/a2dp.c:421:31: note: expected ‘struct a2dp_sep *’ but argument is of type ‘GSList *’ {aka ‘struct _GSList *’}
profiles/audio/a2dp.c:430:31: error: passing argument 2 of ‘cb->config_cb’ from incompatible pointer type [-Werror=incompatible-pointer-types]
  430 |    cb->config_cb(s->session, s->seps, stream,
      |                              ~^~~~~~
      |                               |
      |                               GSList * {aka struct _GSList *}
profiles/audio/a2dp.c:430:31: note: expected ‘struct a2dp_sep *’ but argument is of type ‘GSList *’ {aka ‘struct _GSList *’}
profiles/audio/a2dp.c: In function ‘channel_free’:
profiles/audio/a2dp.c:1577:42: error: passing argument 3 of ‘finalize_setup_errno’ from incompatible pointer type [-Werror=incompatible-pointer-types]
 1577 |   finalize_setup_errno(setup, -ENOTCONN, finalize_all, NULL);
      |                                          ^~~~~~~~~~~~
      |                                          |
      |                                          void (*)(struct a2dp_setup *)
profiles/audio/a2dp.c:262:18: note: expected ‘GSourceFunc’ {aka ‘int (*)(void *)’} but argument is of type ‘void (*)(struct a2dp_setup *)’
  262 |      GSourceFunc cb1, ...)
      |      ~~~~~~~~~~~~^~~
cc1: all warnings being treated as errors
make[1]: *** [Makefile:8531: profiles/audio/bluetoothd-a2dp.o] Error 1
make: *** [Makefile:10406: check] Error 2


##############################
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 - FAIL
Desc: Build BlueZ source with '--enable-external-ell' configuration
Output:
profiles/audio/a2dp.c: In function ‘finalize_all’:
profiles/audio/a2dp.c:421:31: error: passing argument 2 of ‘cb->select_cb’ from incompatible pointer type [-Werror=incompatible-pointer-types]
  421 |    cb->select_cb(s->session, s->seps, s->caps,
      |                              ~^~~~~~
      |                               |
      |                               GSList * {aka struct _GSList *}
profiles/audio/a2dp.c:421:31: note: expected ‘struct a2dp_sep *’ but argument is of type ‘GSList *’ {aka ‘struct _GSList *’}
profiles/audio/a2dp.c:430:31: error: passing argument 2 of ‘cb->config_cb’ from incompatible pointer type [-Werror=incompatible-pointer-types]
  430 |    cb->config_cb(s->session, s->seps, stream,
      |                              ~^~~~~~
      |                               |
      |                               GSList * {aka struct _GSList *}
profiles/audio/a2dp.c:430:31: note: expected ‘struct a2dp_sep *’ but argument is of type ‘GSList *’ {aka ‘struct _GSList *’}
profiles/audio/a2dp.c: In function ‘channel_free’:
profiles/audio/a2dp.c:1577:42: error: passing argument 3 of ‘finalize_setup_errno’ from incompatible pointer type [-Werror=incompatible-pointer-types]
 1577 |   finalize_setup_errno(setup, -ENOTCONN, finalize_all, NULL);
      |                                          ^~~~~~~~~~~~
      |                                          |
      |                                          void (*)(struct a2dp_setup *)
profiles/audio/a2dp.c:262:18: note: expected ‘GSourceFunc’ {aka ‘int (*)(void *)’} but argument is of type ‘void (*)(struct a2dp_setup *)’
  262 |      GSourceFunc cb1, ...)
      |      ~~~~~~~~~~~~^~~
cc1: all warnings being treated as errors
make[1]: *** [Makefile:8531: profiles/audio/bluetoothd-a2dp.o] Error 1
make: *** [Makefile:4134: all] Error 2




---
Regards,
Linux Bluetooth


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