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From: Desmond Cheong Zhi Xi <desmondcheongzx@gmail.com>
To: marcel@holtmann.org, johan.hedberg@gmail.com,
	luiz.dentz@gmail.com, davem@davemloft.net, kuba@kernel.org,
	sudipm.mukherjee@gmail.com
Cc: Desmond Cheong Zhi Xi <desmondcheongzx@gmail.com>,
	linux-bluetooth@vger.kernel.org, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org, skhan@linuxfoundation.org,
	gregkh@linuxfoundation.org,
	linux-kernel-mentees@lists.linuxfoundation.org
Subject: [PATCH v6 0/6] Bluetooth: fix locking and socket killing in SCO and RFCOMM
Date: Tue, 10 Aug 2021 12:14:04 +0800	[thread overview]
Message-ID: <20210810041410.142035-1-desmondcheongzx@gmail.com> (raw)

Hi,

This patch series started out as a fix for "inconsistent lock state in
sco_sock_timeout" reported by Syzbot [1].

Patch 1 is sufficient to fix this error. This was also confirmed by the
reproducer for "BUG: corrupted list in kobject_add_internal (3)" [2]
which consistently hits the inconsistent lock state error.

However, while testing the proposed fix, the reproducer for [1] would
randomly return a human-unreadable error [3]. After further
investigation, this bug seems to be caused by an unrelated error with
forking [4].

While trying to fix the mysterious error, additional fixes were added,
such as switching to lock_sock and serializing _{set,clear}_timer.

Additionally, as the reproducer kept hitting the oom-killer, a fix for
SCO socket killing was also added.

The reproducer for [1] was robust enough to catch errors with these
additional fixes, hence all the patches in this series were squashed then
tested with the reproducer for [1].

Overall, this series makes the following changes:

- Patch 1: Schedule SCO sock timeouts with delayed_work to avoid
inconsistent lock usage (removes SOFTIRQs from SCO)

- Patch 2: Avoid a circular dependency between hci_dev_lock and
lock_sock (enables the switch to lock_sock)

- Patch 3: Switch to lock_sock in SCO now that SOFTIRQs and potential
deadlocks are removed

- Patch 4: Serialize calls to sco_sock_{set,clear}_timer

- Patch 5: Switch to lock_sock in RFCOMM

- Patch 6: fix SCO socket killing

v5 -> v6:
- Removed hard tab characters from patch 2's commit message. As
suggested by the Bluez test bot.
- Removed unnecessary dedicated variables for struct delayed_work* in
sco_sock_{set,clear}_timer as suggested by Luiz Augusto von Dentz.

v4 -> v5:
- Renamed the delayed_work variable, moved checks for sco_pi(sk)->conn
into sco_sock_{clear,set}_timer, as suggested by Luiz Augusto von Dentz
and Marcel Holtmann.
- Added check for conn->sk in sco_sock_timeout, accompanied by a
sock_hold to avoid UAF errors.
- Added check to flush work items before freeing conn.
- Avoid a circular dependency between hci_dev_lock and lock_sock.
- Switch to lock_sock in SCO, as suggested by Marcel Holtmann.
- Serial calls to sco_sock_{set,clear}_timer.
- Switch to lock_sock in RFCOMM, as suggested by Marcel Holtmann.
- Add a fix for SCO socket killing.

v3 -> v4:
- Switch to using delayed_work to schedule SCO sock timeouts instead
of using local_bh_disable. As suggested by Luiz Augusto von Dentz.

v2 -> v3:
- Split SCO and RFCOMM code changes, as suggested by Luiz Augusto von
Dentz.
- Simplify local bh disabling in SCO by using local_bh_disable/enable
inside sco_chan_del since local_bh_disable/enable pairs are reentrant.

v1 -> v2:
- Instead of pulling out the clean-up code out from sco_chan_del and
using it directly in sco_conn_del, disable local softirqs for relevant
sections.
- Disable local softirqs more thoroughly for instances of
bh_lock_sock/bh_lock_sock_nested in the bluetooth subsystem.
Specifically, the calls in af_bluetooth.c and rfcomm/sock.c are now made
with local softirqs disabled as well.

Link: https://syzkaller.appspot.com/bug?id=9089d89de0502e120f234ca0fc8a703f7368b31e [1]

Link: https://syzkaller.appspot.com/bug?extid=66264bf2fd0476be7e6c [2]

Link: https://syzkaller.appspot.com/text?tag=CrashReport&x=172d819a300000 [3]

Link: https://syzkaller.appspot.com/bug?id=e1bf7ba90d8dafcf318666192aba1cfd65507377 [4]

Best wishes,
Desmond

Desmond Cheong Zhi Xi (6):
  Bluetooth: schedule SCO timeouts with delayed_work
  Bluetooth: avoid circular locks in sco_sock_connect
  Bluetooth: switch to lock_sock in SCO
  Bluetooth: serialize calls to sco_sock_{set,clear}_timer
  Bluetooth: switch to lock_sock in RFCOMM
  Bluetooth: fix repeated calls to sco_sock_kill

 net/bluetooth/rfcomm/sock.c |   8 +--
 net/bluetooth/sco.c         | 101 ++++++++++++++++++++----------------
 2 files changed, 60 insertions(+), 49 deletions(-)

-- 
2.25.1


WARNING: multiple messages have this Message-ID
From: Desmond Cheong Zhi Xi <desmondcheongzx@gmail.com>
To: marcel@holtmann.org, johan.hedberg@gmail.com,
	luiz.dentz@gmail.com, davem@davemloft.net, kuba@kernel.org,
	sudipm.mukherjee@gmail.com
Cc: linux-kernel@vger.kernel.org, linux-bluetooth@vger.kernel.org,
	netdev@vger.kernel.org,
	Desmond Cheong Zhi Xi <desmondcheongzx@gmail.com>,
	linux-kernel-mentees@lists.linuxfoundation.org
Subject: [PATCH v6 0/6] Bluetooth: fix locking and socket killing in SCO and RFCOMM
Date: Tue, 10 Aug 2021 12:14:04 +0800	[thread overview]
Message-ID: <20210810041410.142035-1-desmondcheongzx@gmail.com> (raw)

Hi,

This patch series started out as a fix for "inconsistent lock state in
sco_sock_timeout" reported by Syzbot [1].

Patch 1 is sufficient to fix this error. This was also confirmed by the
reproducer for "BUG: corrupted list in kobject_add_internal (3)" [2]
which consistently hits the inconsistent lock state error.

However, while testing the proposed fix, the reproducer for [1] would
randomly return a human-unreadable error [3]. After further
investigation, this bug seems to be caused by an unrelated error with
forking [4].

While trying to fix the mysterious error, additional fixes were added,
such as switching to lock_sock and serializing _{set,clear}_timer.

Additionally, as the reproducer kept hitting the oom-killer, a fix for
SCO socket killing was also added.

The reproducer for [1] was robust enough to catch errors with these
additional fixes, hence all the patches in this series were squashed then
tested with the reproducer for [1].

Overall, this series makes the following changes:

- Patch 1: Schedule SCO sock timeouts with delayed_work to avoid
inconsistent lock usage (removes SOFTIRQs from SCO)

- Patch 2: Avoid a circular dependency between hci_dev_lock and
lock_sock (enables the switch to lock_sock)

- Patch 3: Switch to lock_sock in SCO now that SOFTIRQs and potential
deadlocks are removed

- Patch 4: Serialize calls to sco_sock_{set,clear}_timer

- Patch 5: Switch to lock_sock in RFCOMM

- Patch 6: fix SCO socket killing

v5 -> v6:
- Removed hard tab characters from patch 2's commit message. As
suggested by the Bluez test bot.
- Removed unnecessary dedicated variables for struct delayed_work* in
sco_sock_{set,clear}_timer as suggested by Luiz Augusto von Dentz.

v4 -> v5:
- Renamed the delayed_work variable, moved checks for sco_pi(sk)->conn
into sco_sock_{clear,set}_timer, as suggested by Luiz Augusto von Dentz
and Marcel Holtmann.
- Added check for conn->sk in sco_sock_timeout, accompanied by a
sock_hold to avoid UAF errors.
- Added check to flush work items before freeing conn.
- Avoid a circular dependency between hci_dev_lock and lock_sock.
- Switch to lock_sock in SCO, as suggested by Marcel Holtmann.
- Serial calls to sco_sock_{set,clear}_timer.
- Switch to lock_sock in RFCOMM, as suggested by Marcel Holtmann.
- Add a fix for SCO socket killing.

v3 -> v4:
- Switch to using delayed_work to schedule SCO sock timeouts instead
of using local_bh_disable. As suggested by Luiz Augusto von Dentz.

v2 -> v3:
- Split SCO and RFCOMM code changes, as suggested by Luiz Augusto von
Dentz.
- Simplify local bh disabling in SCO by using local_bh_disable/enable
inside sco_chan_del since local_bh_disable/enable pairs are reentrant.

v1 -> v2:
- Instead of pulling out the clean-up code out from sco_chan_del and
using it directly in sco_conn_del, disable local softirqs for relevant
sections.
- Disable local softirqs more thoroughly for instances of
bh_lock_sock/bh_lock_sock_nested in the bluetooth subsystem.
Specifically, the calls in af_bluetooth.c and rfcomm/sock.c are now made
with local softirqs disabled as well.

Link: https://syzkaller.appspot.com/bug?id=9089d89de0502e120f234ca0fc8a703f7368b31e [1]

Link: https://syzkaller.appspot.com/bug?extid=66264bf2fd0476be7e6c [2]

Link: https://syzkaller.appspot.com/text?tag=CrashReport&x=172d819a300000 [3]

Link: https://syzkaller.appspot.com/bug?id=e1bf7ba90d8dafcf318666192aba1cfd65507377 [4]

Best wishes,
Desmond

Desmond Cheong Zhi Xi (6):
  Bluetooth: schedule SCO timeouts with delayed_work
  Bluetooth: avoid circular locks in sco_sock_connect
  Bluetooth: switch to lock_sock in SCO
  Bluetooth: serialize calls to sco_sock_{set,clear}_timer
  Bluetooth: switch to lock_sock in RFCOMM
  Bluetooth: fix repeated calls to sco_sock_kill

 net/bluetooth/rfcomm/sock.c |   8 +--
 net/bluetooth/sco.c         | 101 ++++++++++++++++++++----------------
 2 files changed, 60 insertions(+), 49 deletions(-)

-- 
2.25.1

_______________________________________________
Linux-kernel-mentees mailing list
Linux-kernel-mentees@lists.linuxfoundation.org
https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees

             reply	other threads:[~2021-08-10  4:17 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-10  4:14 Desmond Cheong Zhi Xi [this message]
2021-08-10  4:14 ` Desmond Cheong Zhi Xi
2021-08-10  4:14 ` [PATCH v6 1/6] Bluetooth: schedule SCO timeouts with delayed_work Desmond Cheong Zhi Xi
2021-08-10  4:14   ` Desmond Cheong Zhi Xi
2021-08-10  5:14   ` Bluetooth: fix locking and socket killing in SCO and RFCOMM bluez.test.bot
2021-08-10 17:51     ` Luiz Augusto von Dentz
2021-09-02 19:17   ` [PATCH v6 1/6] Bluetooth: schedule SCO timeouts with delayed_work Eric Dumazet
2021-09-02 19:17     ` Eric Dumazet
2021-09-02 19:32     ` Desmond Cheong Zhi Xi
2021-09-02 19:32       ` Desmond Cheong Zhi Xi
2021-09-02 21:41       ` Eric Dumazet
2021-09-02 21:41         ` Eric Dumazet
2021-09-02 22:53         ` Desmond Cheong Zhi Xi
2021-09-02 22:53           ` Desmond Cheong Zhi Xi
2021-09-02 23:05           ` Desmond Cheong Zhi Xi
2021-09-02 23:05             ` Desmond Cheong Zhi Xi
2021-09-02 23:42             ` Luiz Augusto von Dentz
2021-09-02 23:42               ` Luiz Augusto von Dentz
2021-09-03  3:17               ` Desmond Cheong Zhi Xi
2021-09-03  3:17                 ` Desmond Cheong Zhi Xi
2021-08-10  4:14 ` [PATCH v6 2/6] Bluetooth: avoid circular locks in sco_sock_connect Desmond Cheong Zhi Xi
2021-08-10  4:14   ` Desmond Cheong Zhi Xi
2021-08-10  4:14 ` [PATCH v6 3/6] Bluetooth: switch to lock_sock in SCO Desmond Cheong Zhi Xi
2021-08-10  4:14   ` Desmond Cheong Zhi Xi
2021-08-10  4:14 ` [PATCH v6 4/6] Bluetooth: serialize calls to sco_sock_{set,clear}_timer Desmond Cheong Zhi Xi
2021-08-10  4:14   ` [PATCH v6 4/6] Bluetooth: serialize calls to sco_sock_{set, clear}_timer Desmond Cheong Zhi Xi
2021-08-10  4:14 ` [PATCH v6 5/6] Bluetooth: switch to lock_sock in RFCOMM Desmond Cheong Zhi Xi
2021-08-10  4:14   ` Desmond Cheong Zhi Xi
2021-08-10  4:14 ` [PATCH v6 6/6] Bluetooth: fix repeated calls to sco_sock_kill Desmond Cheong Zhi Xi
2021-08-10  4:14   ` Desmond Cheong Zhi Xi

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