[0/2] Bluetooth: ISO: iso_listen_bis fixes

[0/2] Bluetooth: ISO: iso_listen_bis fixes

[Iulia Tanasescu]

This patch adds some fixes for the iso_listen_bis function:

The first commit fixes the circular locking dependency warning
caused by iso_listen_bis attempting to lock the hdev while the
socket is locked from the caller function.

The second commit fixes the fact that hci_dev_put is only called
if iso_listen_bis returns successfully. Otherwise, the hdev will
still be held from hci_get_route.

Iulia Tanasescu (2):
  Bluetooth: ISO: Fix circular locking dependency warning
  Bluetooth: ISO: Always release hdev at the end of iso_listen_bis

 net/bluetooth/iso.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

-- 
2.39.2

[1/2] Bluetooth: ISO: Fix circular locking dependency warning

[Iulia Tanasescu]

This fixes the circular locking dependency warning caused
by iso_listen_bis acquiring the hdev lock while the socket
has been locked in the caller function.

======================================================
WARNING: possible circular locking dependency detected
6.8.0-rc5+ #1 Not tainted
------------------------------------------------------
iso-tester/2950 is trying to acquire lock:
ffff88817a048080 (&hdev->lock){+.+.}-{3:3}, at: iso_sock_listen+0x305/0x8d0

               but task is already holding lock:
ffff888197c39278 (sk_lock-AF_BLUETOOTH-BTPROTO_ISO){+.+.}-{0:0},
               at: iso_sock_listen+0x91/0x8d0

               which lock already depends on the new lock.

               the existing dependency chain (in reverse order) is:

 -> #1 (sk_lock-AF_BLUETOOTH-BTPROTO_ISO){+.+.}-{0:0}:
        lock_sock_nested+0x3b/0xb0
        iso_connect_cis+0x185/0x540
        iso_sock_connect+0x445/0x7e0
        __sys_connect_file+0xd5/0x100
        __sys_connect+0x11e/0x150
        __x64_sys_connect+0x42/0x60
        do_syscall_64+0x8d/0x150
        entry_SYSCALL_64_after_hwframe+0x6e/0x76

-> #0 (&hdev->lock){+.+.}-{3:3}:
        __lock_acquire+0x208f/0x3720
        lock_acquire+0x16d/0x3f0
        __mutex_lock+0x155/0x1310
        mutex_lock_nested+0x1b/0x30
        iso_sock_listen+0x305/0x8d0
        __sys_listen+0x106/0x190
        __x64_sys_listen+0x30/0x40
        do_syscall_64+0x8d/0x150
        entry_SYSCALL_64_after_hwframe+0x6e/0x76

        other info that might help us debug this:

Possible unsafe locking scenario:

        CPU0                    CPU1
        ----                    ----
   lock(sk_lock-AF_BLUETOOTH-BTPROTO_ISO);
                                lock(&hdev->lock);
                                lock(sk_lock-AF_BLUETOOTH-BTPROTO_ISO);
   lock(&hdev->lock);

                *** DEADLOCK ***

1 lock held by iso-tester/2950:
0: ffff888197c39278 (sk_lock-AF_BLUETOOTH-BTPROTO_ISO){+.+.}-{0:0},
                at: iso_sock_listen+0x91/0x8d0

Signed-off-by: Iulia Tanasescu <iulia.tanasescu@nxp.com>
---
 net/bluetooth/iso.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/net/bluetooth/iso.c b/net/bluetooth/iso.c
index 30c777c469f9..163b07db575d 100644
--- a/net/bluetooth/iso.c
+++ b/net/bluetooth/iso.c
@@ -1069,6 +1069,7 @@ static int iso_sock_connect(struct socket *sock, struct sockaddr *addr,
 	return err;
 }
 
+/* This function requires the caller to hold sk lock */
 static int iso_listen_bis(struct sock *sk)
 {
 	struct hci_dev *hdev;
@@ -1095,7 +1096,12 @@ static int iso_listen_bis(struct sock *sk)
 	if (!hdev)
 		return -EHOSTUNREACH;
 
+	/* To avoid circular locking dependencies,
+	 * hdev should be locked first before sk.
+	 */
+	release_sock(sk);
 	hci_dev_lock(hdev);
+	lock_sock(sk);
 
 	/* Fail if user set invalid QoS */
 	if (iso_pi(sk)->qos_user_set && !check_bcast_qos(&iso_pi(sk)->qos)) {
@@ -1128,7 +1134,10 @@ static int iso_listen_bis(struct sock *sk)
 	hci_dev_put(hdev);
 
 unlock:
+	/* Unlock order should be in reverse from lock order. */
+	release_sock(sk);
 	hci_dev_unlock(hdev);
+	lock_sock(sk);
 	return err;
 }
 
-- 
2.39.2

[2/2] Bluetooth: ISO: Always release hdev at the end of iso_listen_bis

[Iulia Tanasescu]

Since hci_get_route holds the device before returning, the hdev
should be released with hci_dev_put at the end of iso_listen_bis
even if the function returns with an error.

Signed-off-by: Iulia Tanasescu <iulia.tanasescu@nxp.com>
---
 net/bluetooth/iso.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/bluetooth/iso.c b/net/bluetooth/iso.c
index 163b07db575d..b1a211b75625 100644
--- a/net/bluetooth/iso.c
+++ b/net/bluetooth/iso.c
@@ -1131,13 +1131,13 @@ static int iso_listen_bis(struct sock *sk)
 		goto unlock;
 	}
 
-	hci_dev_put(hdev);
-
 unlock:
 	/* Unlock order should be in reverse from lock order. */
 	release_sock(sk);
 	hci_dev_unlock(hdev);
 	lock_sock(sk);
+
+	hci_dev_put(hdev);
 	return err;
 }
 
-- 
2.39.2

RE: Bluetooth: ISO: iso_listen_bis fixes

[bluez.test.bot]

[-- Attachment #1: Type: text/plain, Size: 1696 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=832164

---Test result---

Test Summary:
CheckPatch                    PASS      1.28 seconds
GitLint                       PASS      0.61 seconds
SubjectPrefix                 PASS      0.23 seconds
BuildKernel                   PASS      28.06 seconds
CheckAllWarning               PASS      31.18 seconds
CheckSparse                   PASS      38.29 seconds
CheckSmatch                   PASS      99.54 seconds
BuildKernel32                 PASS      27.30 seconds
TestRunnerSetup               PASS      506.43 seconds
TestRunner_l2cap-tester       PASS      20.19 seconds
TestRunner_iso-tester         PASS      29.34 seconds
TestRunner_bnep-tester        PASS      4.76 seconds
TestRunner_mgmt-tester        FAIL      112.37 seconds
TestRunner_rfcomm-tester      PASS      7.46 seconds
TestRunner_sco-tester         PASS      14.97 seconds
TestRunner_ioctl-tester       PASS      7.82 seconds
TestRunner_mesh-tester        PASS      5.91 seconds
TestRunner_smp-tester         PASS      6.89 seconds
TestRunner_userchan-tester    PASS      4.99 seconds
IncrementalBuild              PASS      31.30 seconds

Details
##############################
Test: TestRunner_mgmt-tester - FAIL
Desc: Run mgmt-tester with test-runner
Output:
Total: 492, Passed: 489 (99.4%), Failed: 1, Not Run: 2

Failed Test Cases
LL Privacy - Remove Device 4 (Disable Adv)           Timed out    1.906 seconds


---
Regards,
Linux Bluetooth

Re: [1/2] Bluetooth: ISO: Fix circular locking dependency warning

[Luiz Augusto von Dentz]

Hi Iulia,

On Mon, Mar 4, 2024 at 11:51 AM Iulia Tanasescu <iulia.tanasescu@nxp.com> wrote:
>
> This fixes the circular locking dependency warning caused
> by iso_listen_bis acquiring the hdev lock while the socket
> has been locked in the caller function.
>
> ======================================================
> WARNING: possible circular locking dependency detected
> 6.8.0-rc5+ #1 Not tainted
> ------------------------------------------------------
> iso-tester/2950 is trying to acquire lock:
> ffff88817a048080 (&hdev->lock){+.+.}-{3:3}, at: iso_sock_listen+0x305/0x8d0
>
>                but task is already holding lock:
> ffff888197c39278 (sk_lock-AF_BLUETOOTH-BTPROTO_ISO){+.+.}-{0:0},
>                at: iso_sock_listen+0x91/0x8d0
>
>                which lock already depends on the new lock.
>
>                the existing dependency chain (in reverse order) is:
>
>  -> #1 (sk_lock-AF_BLUETOOTH-BTPROTO_ISO){+.+.}-{0:0}:
>         lock_sock_nested+0x3b/0xb0
>         iso_connect_cis+0x185/0x540
>         iso_sock_connect+0x445/0x7e0
>         __sys_connect_file+0xd5/0x100
>         __sys_connect+0x11e/0x150
>         __x64_sys_connect+0x42/0x60
>         do_syscall_64+0x8d/0x150
>         entry_SYSCALL_64_after_hwframe+0x6e/0x76
>
> -> #0 (&hdev->lock){+.+.}-{3:3}:
>         __lock_acquire+0x208f/0x3720
>         lock_acquire+0x16d/0x3f0
>         __mutex_lock+0x155/0x1310
>         mutex_lock_nested+0x1b/0x30
>         iso_sock_listen+0x305/0x8d0
>         __sys_listen+0x106/0x190
>         __x64_sys_listen+0x30/0x40
>         do_syscall_64+0x8d/0x150
>         entry_SYSCALL_64_after_hwframe+0x6e/0x76
>
>         other info that might help us debug this:
>
> Possible unsafe locking scenario:
>
>         CPU0                    CPU1
>         ----                    ----
>    lock(sk_lock-AF_BLUETOOTH-BTPROTO_ISO);
>                                 lock(&hdev->lock);
>                                 lock(sk_lock-AF_BLUETOOTH-BTPROTO_ISO);
>    lock(&hdev->lock);
>
>                 *** DEADLOCK ***
>
> 1 lock held by iso-tester/2950:
> 0: ffff888197c39278 (sk_lock-AF_BLUETOOTH-BTPROTO_ISO){+.+.}-{0:0},
>                 at: iso_sock_listen+0x91/0x8d0
>
> Signed-off-by: Iulia Tanasescu <iulia.tanasescu@nxp.com>
> ---
>  net/bluetooth/iso.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
>
> diff --git a/net/bluetooth/iso.c b/net/bluetooth/iso.c
> index 30c777c469f9..163b07db575d 100644
> --- a/net/bluetooth/iso.c
> +++ b/net/bluetooth/iso.c
> @@ -1069,6 +1069,7 @@ static int iso_sock_connect(struct socket *sock, struct sockaddr *addr,
>         return err;
>  }
>
> +/* This function requires the caller to hold sk lock */
>  static int iso_listen_bis(struct sock *sk)
>  {
>         struct hci_dev *hdev;
> @@ -1095,7 +1096,12 @@ static int iso_listen_bis(struct sock *sk)
>         if (!hdev)
>                 return -EHOSTUNREACH;
>
> +       /* To avoid circular locking dependencies,
> +        * hdev should be locked first before sk.
> +        */
> +       release_sock(sk);

Don't really like the idea of having to release the lock here since
that in the meantime can cause it to destroy the socket while waiting
for hci_dev_lock so perhaps we need to look into mutex_lock_nested.

>         hci_dev_lock(hdev);
> +       lock_sock(sk);
>
>         /* Fail if user set invalid QoS */
>         if (iso_pi(sk)->qos_user_set && !check_bcast_qos(&iso_pi(sk)->qos)) {
> @@ -1128,7 +1134,10 @@ static int iso_listen_bis(struct sock *sk)
>         hci_dev_put(hdev);
>
>  unlock:
> +       /* Unlock order should be in reverse from lock order. */
> +       release_sock(sk);
>         hci_dev_unlock(hdev);
> +       lock_sock(sk);
>         return err;
>  }
>
> --
> 2.39.2
>


-- 
Luiz Augusto von Dentz