From: Arseniy Krasnov avkrasnov@salutedevices.com

[ Upstream commit 2935e556850e9c94d7a00adf14d3cd7fe406ac03 ]

Function 'hci_discovery_filter_clear()' frees 'uuids' array and then sets it to NULL. There is a tiny chance of the following race:

'hci_cmd_sync_work()'

'update_passive_scan_sync()'

'hci_update_passive_scan_sync()'

'hci_discovery_filter_clear()' kfree(uuids);

<-------------------------preempted--------------------------------> 'start_service_discovery()'

'hci_discovery_filter_clear()' kfree(uuids); // DOUBLE FREE

<-------------------------preempted-------------------------------->

uuids = NULL;

To fix it let's add locking around 'kfree()' call and NULL pointer assignment. Otherwise the following backtrace fires:

[ ] ------------[ cut here ]------------ [ ] kernel BUG at mm/slub.c:547! [ ] Internal error: Oops - BUG: 00000000f2000800 [#1] PREEMPT SMP [ ] CPU: 3 UID: 0 PID: 246 Comm: bluetoothd Tainted: G O 6.12.19-kernel #1 [ ] Tainted: [O]=OOT_MODULE [ ] pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) [ ] pc : __slab_free+0xf8/0x348 [ ] lr : __slab_free+0x48/0x348 ... [ ] Call trace: [ ] __slab_free+0xf8/0x348 [ ] kfree+0x164/0x27c [ ] start_service_discovery+0x1d0/0x2c0 [ ] hci_sock_sendmsg+0x518/0x924 [ ] __sock_sendmsg+0x54/0x60 [ ] sock_write_iter+0x98/0xf8 [ ] do_iter_readv_writev+0xe4/0x1c8 [ ] vfs_writev+0x128/0x2b0 [ ] do_writev+0xfc/0x118 [ ] __arm64_sys_writev+0x20/0x2c [ ] invoke_syscall+0x68/0xf0 [ ] el0_svc_common.constprop.0+0x40/0xe0 [ ] do_el0_svc+0x1c/0x28 [ ] el0_svc+0x30/0xd0 [ ] el0t_64_sync_handler+0x100/0x12c [ ] el0t_64_sync+0x194/0x198 [ ] Code: 8b0002e6 eb17031f 54fffbe1 d503201f (d4210000) [ ] ---[ end trace 0000000000000000 ]---

Fixes: ad383c2c65a5 ("Bluetooth: hci_sync: Enable advertising when LL privacy is enabled") Signed-off-by: Arseniy Krasnov avkrasnov@salutedevices.com Signed-off-by: Luiz Augusto von Dentz luiz.von.dentz@intel.com [ Minor context change fixed. ] Signed-off-by: Alva Lan alvalan9@foxmail.com --- include/net/bluetooth/hci_core.h | 7 +++++++ 1 file changed, 7 insertions(+)

diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h index 62135b7782f5..c7f402a0a958 100644 --- a/include/net/bluetooth/hci_core.h +++ b/include/net/bluetooth/hci_core.h @@ -29,6 +29,7 @@ #include <linux/idr.h> #include <linux/leds.h> #include <linux/rculist.h> +#include <linux/spinlock.h> #include <linux/srcu.h>

#include <net/bluetooth/hci.h> @@ -95,6 +96,7 @@ struct discovery_state { unsigned long scan_start; unsigned long scan_duration; unsigned long name_resolve_timeout; + spinlock_t lock; };

#define SUSPEND_NOTIFIER_TIMEOUT msecs_to_jiffies(2000) /* 2 seconds */ @@ -869,6 +871,7 @@ static inline void iso_recv(struct hci_conn *hcon, struct sk_buff *skb,

static inline void discovery_init(struct hci_dev *hdev) { + spin_lock_init(&hdev->discovery.lock); hdev->discovery.state = DISCOVERY_STOPPED; INIT_LIST_HEAD(&hdev->discovery.all); INIT_LIST_HEAD(&hdev->discovery.unknown); @@ -883,8 +886,12 @@ static inline void hci_discovery_filter_clear(struct hci_dev *hdev) hdev->discovery.report_invalid_rssi = true; hdev->discovery.rssi = HCI_RSSI_INVALID; hdev->discovery.uuid_count = 0; + + spin_lock(&hdev->discovery.lock); kfree(hdev->discovery.uuids); hdev->discovery.uuids = NULL; + spin_unlock(&hdev->discovery.lock); + hdev->discovery.scan_start = 0; hdev->discovery.scan_duration = 0; }