bluetooth: don't use bitmaps for random flag accesses

[ Upstream commit e1cff7002b716bd0b5f5f4afd4273c99aa8644be ]

The bluetooth code uses our bitmap infrastructure for the two bits (!)
of connection setup flags, and in the process causes odd problems when
it converts between a bitmap and just the regular values of said bits.

It's completely pointless to do things like bitmap_to_arr32() to convert
a bitmap into a u32.  It shoudln't have been a bitmap in the first
place.  The reason to use bitmaps is if you have arbitrary number of
bits you want to manage (not two!), or if you rely on the atomicity
guarantees of the bitmap setting and clearing.

The code could use an "atomic_t" and use "atomic_or/andnot()" to set and
clear the bit values, but considering that it then copies the bitmaps
around with "bitmap_to_arr32()" and friends, there clearly cannot be a
lot of atomicity requirements.

So just use a regular integer.

In the process, this avoids the warnings about erroneous use of
bitmap_from_u64() which were triggered on 32-bit architectures when
conversion from a u64 would access two words (and, surprise, surprise,
only one word is needed - and indeed overkill - for a 2-bit bitmap).

That was always problematic, but the compiler seems to notice it and
warn about the invalid pattern only after commit 0a97953fd221 ("lib: add
bitmap_{from,to}_arr64") changed the exact implementation details of
'bitmap_from_u64()', as reported by Sudip Mukherjee and Stephen Rothwell.

Fixes: fe92ee6425a2 ("Bluetooth: hci_core: Rework hci_conn_params flags")
Link: https://lore.kernel.org/all/YpyJ9qTNHJzz0FHY@debian/
Link: https://lore.kernel.org/all/20220606080631.0c3014f2@canb.auug.org.au/
Link: https://lore.kernel.org/all/20220605162537.1604762-1-yury.norov@gmail.com/
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Reported-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Reviewed-by: Yury Norov <yury.norov@gmail.com>
Cc: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Cc: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
index 4524920e4895d30e115a99e70e6f93de7d50dc09..f397b0a3d631004b6d4df1934596c94974d2d8c9 100644 (file)
--- a/include/net/bluetooth/hci_core.h
+++ b/include/net/bluetooth/hci_core.h
@@ -155,21 +155,18 @@ struct bdaddr_list_with_irk {
        u8 local_irk[16];
 };
 
+/* Bitmask of connection flags */
 enum hci_conn_flags {
-       HCI_CONN_FLAG_REMOTE_WAKEUP,
-       HCI_CONN_FLAG_DEVICE_PRIVACY,
-
-       __HCI_CONN_NUM_FLAGS,
+       HCI_CONN_FLAG_REMOTE_WAKEUP = 1,
+       HCI_CONN_FLAG_DEVICE_PRIVACY = 2,
 };
-
-/* Make sure number of flags doesn't exceed sizeof(current_flags) */
-static_assert(__HCI_CONN_NUM_FLAGS < 32);
+typedef u8 hci_conn_flags_t;
 
 struct bdaddr_list_with_flags {
        struct list_head list;
        bdaddr_t bdaddr;
        u8 bdaddr_type;
-       DECLARE_BITMAP(flags, __HCI_CONN_NUM_FLAGS);
+       hci_conn_flags_t flags;
 };
 
 struct bt_uuid {
@@ -567,7 +564,7 @@ struct hci_dev {
        struct rfkill           *rfkill;
 
        DECLARE_BITMAP(dev_flags, __HCI_NUM_FLAGS);
-       DECLARE_BITMAP(conn_flags, __HCI_CONN_NUM_FLAGS);
+       hci_conn_flags_t        conn_flags;
 
        __s8                    adv_tx_power;
        __u8                    adv_data[HCI_MAX_EXT_AD_LENGTH];
@@ -763,7 +760,7 @@ struct hci_conn_params {
 
        struct hci_conn *conn;
        bool explicit_connect;
-       DECLARE_BITMAP(flags, __HCI_CONN_NUM_FLAGS);
+       hci_conn_flags_t flags;
        u8  privacy_mode;
 };
 

diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index 9e9713f7ddb8482bfc977abe94f31f770d8c20ee..f1feb92040637e36fd9a189b366fb28e2fb03be6 100644 (file)
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -2153,7 +2153,7 @@ int hci_bdaddr_list_add_with_flags(struct list_head *list, bdaddr_t *bdaddr,
 
        bacpy(&entry->bdaddr, bdaddr);
        entry->bdaddr_type = type;
-       bitmap_from_u64(entry->flags, flags);
+       entry->flags = flags;
 
        list_add(&entry->list, list);
 
@@ -2633,7 +2633,7 @@ int hci_register_dev(struct hci_dev *hdev)
         * callback.
         */
        if (hdev->wakeup)
-               set_bit(HCI_CONN_FLAG_REMOTE_WAKEUP, hdev->conn_flags);
+               hdev->conn_flags |= HCI_CONN_FLAG_REMOTE_WAKEUP;
 
        hci_sock_dev_event(hdev, HCI_DEV_REG);
        hci_dev_hold(hdev);

diff --git a/net/bluetooth/hci_request.c b/net/bluetooth/hci_request.c
index f4afe482e3004d69246d0b462bcfe2c466500f3c..95689982eedbcdf8be41bbae234181d9ebdb0cbc 100644 (file)
--- a/net/bluetooth/hci_request.c
+++ b/net/bluetooth/hci_request.c
@@ -482,7 +482,7 @@ static int add_to_accept_list(struct hci_request *req,
 
        /* During suspend, only wakeable devices can be in accept list */
        if (hdev->suspended &&
-           !test_bit(HCI_CONN_FLAG_REMOTE_WAKEUP, params->flags))
+           !(params->flags & HCI_CONN_FLAG_REMOTE_WAKEUP))
                return 0;
 
        *num_entries += 1;

diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
index 6b8d1cd65de45e2f166ed1cafcc5bf15a4e3e8e0..351c2390164d03f35bdbb833eab4627047a915e8 100644 (file)
--- a/net/bluetooth/hci_sync.c
+++ b/net/bluetooth/hci_sync.c
@@ -1637,7 +1637,7 @@ static int hci_le_set_privacy_mode_sync(struct hci_dev *hdev,
         * indicates that LL Privacy has been enabled and
         * HCI_OP_LE_SET_PRIVACY_MODE is supported.
         */
-       if (!test_bit(HCI_CONN_FLAG_DEVICE_PRIVACY, params->flags))
+       if (!(params->flags & HCI_CONN_FLAG_DEVICE_PRIVACY))
                return 0;
 
        irk = hci_find_irk_by_addr(hdev, &params->addr, params->addr_type);
@@ -1666,7 +1666,7 @@ static int hci_le_add_accept_list_sync(struct hci_dev *hdev,
 
        /* During suspend, only wakeable devices can be in acceptlist */
        if (hdev->suspended &&
-           !test_bit(HCI_CONN_FLAG_REMOTE_WAKEUP, params->flags))
+           !(params->flags & HCI_CONN_FLAG_REMOTE_WAKEUP))
                return 0;
 
        /* Select filter policy to accept all advertising */
@@ -4856,7 +4856,7 @@ static int hci_update_event_filter_sync(struct hci_dev *hdev)
        hci_clear_event_filter_sync(hdev);
 
        list_for_each_entry(b, &hdev->accept_list, list) {
-               if (!test_bit(HCI_CONN_FLAG_REMOTE_WAKEUP, b->flags))
+               if (!(b->flags & HCI_CONN_FLAG_REMOTE_WAKEUP))
                        continue;
 
                bt_dev_dbg(hdev, "Adding event filters for %pMR", &b->bdaddr);

diff --git a/net/bluetooth/mgmt.c b/net/bluetooth/mgmt.c
index 16cd2e7a10da1979e88e40ee4ead1d70cc4c5d71..943cdc9ec76303c5725a8c7908d051c2d1d4da17 100644 (file)
--- a/net/bluetooth/mgmt.c
+++ b/net/bluetooth/mgmt.c
@@ -4009,10 +4009,11 @@ static int exp_ll_privacy_feature_changed(bool enabled, struct hci_dev *hdev,
        memcpy(ev.uuid, rpa_resolution_uuid, 16);
        ev.flags = cpu_to_le32((enabled ? BIT(0) : 0) | BIT(1));
 
+       // Do we need to be atomic with the conn_flags?
        if (enabled && privacy_mode_capable(hdev))
-               set_bit(HCI_CONN_FLAG_DEVICE_PRIVACY, hdev->conn_flags);
+               hdev->conn_flags |= HCI_CONN_FLAG_DEVICE_PRIVACY;
        else
-               clear_bit(HCI_CONN_FLAG_DEVICE_PRIVACY, hdev->conn_flags);
+               hdev->conn_flags &= ~HCI_CONN_FLAG_DEVICE_PRIVACY;
 
        return mgmt_limited_event(MGMT_EV_EXP_FEATURE_CHANGED, hdev,
                                  &ev, sizeof(ev),
@@ -4431,8 +4432,7 @@ static int get_device_flags(struct sock *sk, struct hci_dev *hdev, void *data,
 
        hci_dev_lock(hdev);
 
-       bitmap_to_arr32(&supported_flags, hdev->conn_flags,
-                       __HCI_CONN_NUM_FLAGS);
+       supported_flags = hdev->conn_flags;
 
        memset(&rp, 0, sizeof(rp));
 
@@ -4443,8 +4443,7 @@ static int get_device_flags(struct sock *sk, struct hci_dev *hdev, void *data,
                if (!br_params)
                        goto done;
 
-               bitmap_to_arr32(&current_flags, br_params->flags,
-                               __HCI_CONN_NUM_FLAGS);
+               current_flags = br_params->flags;
        } else {
                params = hci_conn_params_lookup(hdev, &cp->addr.bdaddr,
                                                le_addr_type(cp->addr.type));
@@ -4452,8 +4451,7 @@ static int get_device_flags(struct sock *sk, struct hci_dev *hdev, void *data,
                if (!params)
                        goto done;
 
-               bitmap_to_arr32(&current_flags, params->flags,
-                               __HCI_CONN_NUM_FLAGS);
+               current_flags = params->flags;
        }
 
        bacpy(&rp.addr.bdaddr, &cp->addr.bdaddr);
@@ -4498,8 +4496,8 @@ static int set_device_flags(struct sock *sk, struct hci_dev *hdev, void *data,
                   &cp->addr.bdaddr, cp->addr.type,
                   __le32_to_cpu(current_flags));
 
-       bitmap_to_arr32(&supported_flags, hdev->conn_flags,
-                       __HCI_CONN_NUM_FLAGS);
+       // We should take hci_dev_lock() early, I think.. conn_flags can change
+       supported_flags = hdev->conn_flags;
 
        if ((supported_flags | current_flags) != supported_flags) {
                bt_dev_warn(hdev, "Bad flag given (0x%x) vs supported (0x%0x)",
@@ -4515,7 +4513,7 @@ static int set_device_flags(struct sock *sk, struct hci_dev *hdev, void *data,
                                                              cp->addr.type);
 
                if (br_params) {
-                       bitmap_from_u64(br_params->flags, current_flags);
+                       br_params->flags = current_flags;
                        status = MGMT_STATUS_SUCCESS;
                } else {
                        bt_dev_warn(hdev, "No such BR/EDR device %pMR (0x%x)",
@@ -4525,15 +4523,11 @@ static int set_device_flags(struct sock *sk, struct hci_dev *hdev, void *data,
                params = hci_conn_params_lookup(hdev, &cp->addr.bdaddr,
                                                le_addr_type(cp->addr.type));
                if (params) {
-                       DECLARE_BITMAP(flags, __HCI_CONN_NUM_FLAGS);
-
-                       bitmap_from_u64(flags, current_flags);
-
                        /* Devices using RPAs can only be programmed in the
                         * acceptlist LL Privacy has been enable otherwise they
                         * cannot mark HCI_CONN_FLAG_REMOTE_WAKEUP.
                         */
-                       if (test_bit(HCI_CONN_FLAG_REMOTE_WAKEUP, flags) &&
+                       if ((current_flags & HCI_CONN_FLAG_REMOTE_WAKEUP) &&
                            !use_ll_privacy(hdev) &&
                            hci_find_irk_by_addr(hdev, &params->addr,
                                                 params->addr_type)) {
@@ -4542,14 +4536,13 @@ static int set_device_flags(struct sock *sk, struct hci_dev *hdev, void *data,
                                goto unlock;
                        }
 
-                       bitmap_from_u64(params->flags, current_flags);
+                       params->flags = current_flags;
                        status = MGMT_STATUS_SUCCESS;
 
                        /* Update passive scan if HCI_CONN_FLAG_DEVICE_PRIVACY
                         * has been set.
                         */
-                       if (test_bit(HCI_CONN_FLAG_DEVICE_PRIVACY,
-                                    params->flags))
+                       if (params->flags & HCI_CONN_FLAG_DEVICE_PRIVACY)
                                hci_update_passive_scan(hdev);
                } else {
                        bt_dev_warn(hdev, "No such LE device %pMR (0x%x)",
@@ -7150,8 +7143,7 @@ static int add_device(struct sock *sk, struct hci_dev *hdev,
                params = hci_conn_params_lookup(hdev, &cp->addr.bdaddr,
                                                addr_type);
                if (params)
-                       bitmap_to_arr32(&current_flags, params->flags,
-                                       __HCI_CONN_NUM_FLAGS);
+                       current_flags = params->flags;
        }
 
        err = hci_cmd_sync_queue(hdev, add_device_sync, NULL, NULL);
@@ -7160,8 +7152,7 @@ static int add_device(struct sock *sk, struct hci_dev *hdev,
 
 added:
        device_added(sk, hdev, &cp->addr.bdaddr, cp->addr.type, cp->action);
-       bitmap_to_arr32(&supported_flags, hdev->conn_flags,
-                       __HCI_CONN_NUM_FLAGS);
+       supported_flags = hdev->conn_flags;
        device_flags_changed(NULL, hdev, &cp->addr.bdaddr, cp->addr.type,
                             supported_flags, current_flags);