5.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Luiz Augusto von Dentz [ Upstream commit f1a8f402f13f94263cf349216c257b2985100927 ] This fixes the following deadlock introduced by 39a92a55be13 ("bluetooth/l2cap: sync sock recv cb and release") ============================================ WARNING: possible recursive locking detected 6.10.0-rc3-g4029dba6b6f1 #6823 Not tainted -------------------------------------------- kworker/u5:0/35 is trying to acquire lock: ffff888002ec2510 (&chan->lock#2/1){+.+.}-{3:3}, at: l2cap_sock_recv_cb+0x44/0x1e0 but task is already holding lock: ffff888002ec2510 (&chan->lock#2/1){+.+.}-{3:3}, at: l2cap_get_chan_by_scid+0xaf/0xd0 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&chan->lock#2/1); lock(&chan->lock#2/1); *** DEADLOCK *** May be due to missing lock nesting notation 3 locks held by kworker/u5:0/35: #0: ffff888002b8a940 ((wq_completion)hci0#2){+.+.}-{0:0}, at: process_one_work+0x750/0x930 #1: ffff888002c67dd0 ((work_completion)(&hdev->rx_work)){+.+.}-{0:0}, at: process_one_work+0x44e/0x930 #2: ffff888002ec2510 (&chan->lock#2/1){+.+.}-{3:3}, at: l2cap_get_chan_by_scid+0xaf/0xd0 To fix the original problem this introduces l2cap_chan_lock at l2cap_conless_channel to ensure that l2cap_sock_recv_cb is called with chan->lock held. Fixes: 89e856e124f9 ("bluetooth/l2cap: sync sock recv cb and release") Signed-off-by: Luiz Augusto von Dentz [ Karl Mehltretter: only the l2cap_core.c and l2cap_sock.c hunks apply to this tree. hci_sync.c and hci_sync.h do not exist here, and the hci_core.c change is an unrelated conversion of hci_dev_cmd() off the old hci_request API. The changes to both L2CAP files apply unmodified. The lock this adds to l2cap_conless_channel() is also the one that commit c531e63871c0 ("Bluetooth: l2cap: always unlock channel in l2cap_conless_channel()") was backported without, so it additionally pairs the l2cap_chan_unlock() that function currently calls on a mutex it never acquired. ] Assisted-by: LLM Signed-off-by: Karl Mehltretter Signed-off-by: Sasha Levin --- net/bluetooth/l2cap_core.c | 3 +++ net/bluetooth/l2cap_sock.c | 13 +------------ 2 files changed, 4 insertions(+), 12 deletions(-) diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c index e974d8038dec8..cb883bd13286a 100644 --- a/net/bluetooth/l2cap_core.c +++ b/net/bluetooth/l2cap_core.c @@ -8055,6 +8055,8 @@ static void l2cap_conless_channel(struct l2cap_conn *conn, __le16 psm, BT_DBG("chan %p, len %d", chan, skb->len); + l2cap_chan_lock(chan); + if (chan->state != BT_BOUND && chan->state != BT_CONNECTED) goto drop; @@ -8072,6 +8074,7 @@ static void l2cap_conless_channel(struct l2cap_conn *conn, __le16 psm, } drop: + l2cap_chan_unlock(chan); l2cap_chan_put(chan); free_skb: kfree_skb(skb); diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c index 9d834f2254626..018b5a0c87ce9 100644 --- a/net/bluetooth/l2cap_sock.c +++ b/net/bluetooth/l2cap_sock.c @@ -1548,18 +1548,9 @@ static int l2cap_sock_recv_cb(struct l2cap_chan *chan, struct sk_buff *skb) struct l2cap_pinfo *pi; int err; - /* To avoid race with sock_release, a chan lock needs to be added here - * to synchronize the sock. - */ - l2cap_chan_hold(chan); - l2cap_chan_lock(chan); sk = chan->data; - - if (!sk) { - l2cap_chan_unlock(chan); - l2cap_chan_put(chan); + if (!sk) return -ENXIO; - } pi = l2cap_pi(sk); lock_sock(sk); @@ -1611,8 +1602,6 @@ static int l2cap_sock_recv_cb(struct l2cap_chan *chan, struct sk_buff *skb) done: release_sock(sk); - l2cap_chan_unlock(chan); - l2cap_chan_put(chan); return err; } -- 2.53.0