[PATCH 6.19 124/220] Bluetooth: HIDP: Fix possible UAF

Greg Kroah-Hartman
2026-03-23T13:58:06Z

From: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

[ Upstream commit dbf666e4fc9bdd975a61bf682b3f75cb0145eedd ]

This fixes the following trace caused by not dropping l2cap_conn
reference when user->remove callback is called:

[ 97.809249] l2cap_conn_free: freeing conn ffff88810a171c00
[ 97.809907] CPU: 1 UID: 0 PID: 1419 Comm: repro_standalon Not tainted 7.0.0-rc1-dirty #14 PREEMPT(lazy)
[ 97.809935] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-debian-1.17.0-1 04/01/2014
[ 97.809947] Call Trace:
[ 97.809954] <TASK>
[ 97.809961] dump_stack_lvl (lib/dump_stack.c:122)
[ 97.809990] l2cap_conn_free (net/bluetooth/l2cap_core.c:1808)
[ 97.810017] l2cap_conn_del (./include/linux/kref.h:66 net/bluetooth/l2cap_core.c:1821 net/bluetooth/l2cap_core.c:1798)
[ 97.810055] l2cap_disconn_cfm (net/bluetooth/l2cap_core.c:7347 (discriminator 1) net/bluetooth/l2cap_core.c:7340 (discriminator 1))
[ 97.810086] ? __pfx_l2cap_disconn_cfm (net/bluetooth/l2cap_core.c:7341)
[ 97.810117] hci_conn_hash_flush (./include/net/bluetooth/hci_core.h:2152 (discriminator 2) net/bluetooth/hci_conn.c:2644 (discriminator 2))
[ 97.810148] hci_dev_close_sync (net/bluetooth/hci_sync.c:5360)
[ 97.810180] ? __pfx_hci_dev_close_sync (net/bluetooth/hci_sync.c:5285)
[ 97.810212] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)
[ 97.810242] ? up_write (./arch/x86/include/asm/atomic64_64.h:87 (discriminator 5) ./include/linux/atomic/atomic-arch-fallback.h:2852 (discriminator 5) ./include/linux/atomic/atomic-long.h:268 (discriminator 5) ./include/linux/atomic/atomic-instrumented.h:3391 (discriminator 5) kernel/locking/rwsem.c:1385 (discriminator 5) kernel/locking/rwsem.c:1643 (discriminator 5))
[ 97.810267] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)
[ 97.810290] ? rcu_is_watching (./arch/x86/include/asm/atomic.h:23 ./include/linux/atomic/atomic-arch-fallback.h:457 ./include/linux/context_tracking.h:128 kernel/rcu/tree.c:752)
[ 97.810320] hci_unregister_dev (net/bluetooth/hci_core.c:504 net/bluetooth/hci_core.c:2716)
[ 97.810346] vhci_release (drivers/bluetooth/hci_vhci.c:691)
[ 97.810375] ? __pfx_vhci_release (drivers/bluetooth/hci_vhci.c:678)
[ 97.810404] __fput (fs/file_table.c:470)
[ 97.810430] task_work_run (kernel/task_work.c:235)
[ 97.810451] ? __pfx_task_work_run (kernel/task_work.c:201)
[ 97.810472] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)
[ 97.810495] ? do_raw_spin_unlock (./include/asm-generic/qspinlock.h:128 (discriminator 5) kernel/locking/spinlock_debug.c:142 (discriminator 5))
[ 97.810527] do_exit (kernel/exit.c:972)
[ 97.810547] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)
[ 97.810574] ? __pfx_do_exit (kernel/exit.c:897)
[ 97.810594] ? lock_acquire (kernel/locking/lockdep.c:470 (discriminator 6) kernel/locking/lockdep.c:5870 (discriminator 6) kernel/locking/lockdep.c:5825 (discriminator 6))
[ 97.810616] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)
[ 97.810639] ? do_raw_spin_lock (kernel/locking/spinlock_debug.c:95 (discriminator 4) kernel/locking/spinlock_debug.c:118 (discriminator 4))
[ 97.810664] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)
[ 97.810688] ? find_held_lock (kernel/locking/lockdep.c:5350 (discriminator 1))
[ 97.810721] do_group_exit (kernel/exit.c:1093)
[ 97.810745] get_signal (kernel/signal.c:3007 (discriminator 1))
[ 97.810772] ? security_file_permission (./arch/x86/include/asm/jump_label.h:37 security/security.c:2366)
[ 97.810803] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)
[ 97.810826] ? vfs_read (fs/read_write.c:555)
[ 97.810854] ? __pfx_get_signal (kernel/signal.c:2800)
[ 97.810880] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)
[ 97.810905] ? __pfx_vfs_read (fs/read_write.c:555)
[ 97.810932] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)
[ 97.810960] arch_do_signal_or_restart (arch/x86/kernel/signal.c:337 (discriminator 1))
[ 97.810990] ? __pfx_arch_do_signal_or_restart (arch/x86/kernel/signal.c:334)
[ 97.811021] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)
[ 97.811055] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)
[ 97.811078] ? ksys_read (fs/read_write.c:707)
[ 97.811106] ? __pfx_ksys_read (fs/read_write.c:707)
[ 97.811137] exit_to_user_mode_loop (kernel/entry/common.c:66 kernel/entry/common.c:98)
[ 97.811169] ? rcu_is_watching (./arch/x86/include/asm/atomic.h:23 ./include/linux/atomic/atomic-arch-fallback.h:457 ./include/linux/context_tracking.h:128 kernel/rcu/tree.c:752)
[ 97.811192] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)
[ 97.811215] ? trace_hardirqs_off (./include/trace/events/preemptirq.h:36 (discriminator 33) kernel/trace/trace_preemptirq.c:95 (discriminator 33) kernel/trace/trace_preemptirq.c:90 (discriminator 33))
[ 97.811240] do_syscall_64 (./include/linux/irq-entry-common.h:226 ./include/linux/irq-entry-common.h:256 ./include/linux/entry-common.h:325 arch/x86/entry/syscall_64.c:100)
[ 97.811268] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)
[ 97.811292] ? exc_page_fault (arch/x86/mm/fault.c:1480 (discriminator 3) arch/x86/mm/fault.c:1527 (discriminator 3))
[ 97.811318] entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)
[ 97.811338] RIP: 0033:0x445cfe
[ 97.811352] Code: Unable to access opcode bytes at 0x445cd4.

Code starting with the faulting instruction
===========================================
[ 97.811360] RSP: 002b:00007f65c41c6dc8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
[ 97.811378] RAX: fffffffffffffe00 RBX: 00007f65c41c76c0 RCX: 0000000000445cfe
[ 97.811391] RDX: 0000000000000400 RSI: 00007f65c41c6e40 RDI: 0000000000000004
[ 97.811403] RBP: 00007f65c41c7250 R08: 0000000000000000 R09: 0000000000000000
[ 97.811415] R10: 0000000000000000 R11: 0000000000000246 R12: ffffffffffffffe8
[ 97.811428] R13: 0000000000000000 R14: 00007fff780a8c00 R15: 00007f65c41c76c0
[ 97.811453] </TASK>
[ 98.402453] ==================================================================
[ 98.403560] BUG: KASAN: use-after-free in __mutex_lock (kernel/locking/mutex.c:199 kernel/locking/mutex.c:694 kernel/locking/mutex.c:776)
[ 98.404541] Read of size 8 at addr ffff888113ee40a8 by task khidpd_00050004/1430
[ 98.405361]
[ 98.405563] CPU: 1 UID: 0 PID: 1430 Comm: khidpd_00050004 Not tainted 7.0.0-rc1-dirty #14 PREEMPT(lazy)
[ 98.405588] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-debian-1.17.0-1 04/01/2014
[ 98.405600] Call Trace:
[ 98.405607] <TASK>
[ 98.405614] dump_stack_lvl (lib/dump_stack.c:122)
[ 98.405641] print_report (mm/kasan/report.c:379 mm/kasan/report.c:482)
[ 98.405667] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)
[ 98.405691] ? __virt_addr_valid (arch/x86/mm/physaddr.c:55)
[ 98.405724] ? __mutex_lock (kernel/locking/mutex.c:199 kernel/locking/mutex.c:694 kernel/locking/mutex.c:776)
[ 98.405748] kasan_report (mm/kasan/report.c:221 mm/kasan/report.c:597)
[ 98.405778] ? __mutex_lock (kernel/locking/mutex.c:199 kernel/locking/mutex.c:694 kernel/locking/mutex.c:776)
[ 98.405807] __mutex_lock (kernel/locking/mutex.c:199 kernel/locking/mutex.c:694 kernel/locking/mutex.c:776)
[ 98.405832] ? do_raw_spin_lock (kernel/locking/spinlock_debug.c:95 (discriminator 4) kernel/locking/spinlock_debug.c:118 (discriminator 4))
[ 98.405859] ? l2cap_unregister_user (./include/linux/list.h:381 (discriminator 2) net/bluetooth/l2cap_core.c:1723 (discriminator 2))
[ 98.405888] ? __pfx_do_raw_spin_lock (kernel/locking/spinlock_debug.c:114)
[ 98.405915] ? __pfx___mutex_lock (kernel/locking/mutex.c:775)
[ 98.405939] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)
[ 98.405963] ? lock_acquire (kernel/locking/lockdep.c:470 (discriminator 6) kernel/locking/lockdep.c:5870 (discriminator 6) kernel/locking/lockdep.c:5825 (discriminator 6))
[ 98.405984] ? find_held_lock (kernel/locking/lockdep.c:5350 (discriminator 1))
[ 98.406015] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)
[ 98.406038] ? lock_release (kernel/locking/lockdep.c:5536 kernel/locking/lockdep.c:5889 kernel/locking/lockdep.c:5875)
[ 98.406061] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)
[ 98.406085] ? _raw_spin_unlock_irqrestore (./arch/x86/include/asm/irqflags.h:42 ./arch/x86/include/asm/irqflags.h:119 ./arch/x86/include/asm/irqflags.h:159 ./include/linux/spinlock_api_smp.h:178 kernel/locking/spinlock.c:194)
[ 98.406107] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)
[ 98.406130] ? __timer_delete_sync (kernel/time/timer.c:1592)
[ 98.406158] ? l2cap_unregister_user (./include/linux/list.h:381 (discriminator 2) net/bluetooth/l2cap_core.c:1723 (discriminator 2))
[ 98.406186] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)
[ 98.406210] l2cap_unregister_user (./include/linux/list.h:381 (discriminator 2) net/bluetooth/l2cap_core.c:1723 (discriminator 2))
[ 98.406263] hidp_session_thread (./include/linux/instrumented.h:112 ./include/linux/atomic/atomic-instrumented.h:400 ./include/linux/refcount.h:389 ./include/linux/refcount.h:432 ./include/linux/refcount.h:450 ./include/linux/kref.h:64 net/bluetooth/hidp/core.c:996 net/bluetooth/hidp/core.c:1305)
[ 98.406293] ? __pfx_hidp_session_thread (net/bluetooth/hidp/core.c:1264)
[ 98.406323] ? kthread (kernel/kthread.c:433)
[ 98.406340] ? __pfx_hidp_session_wake_function (net/bluetooth/hidp/core.c:1251)
[ 98.406370] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)
[ 98.406393] ? find_held_lock (kernel/locking/lockdep.c:5350 (discriminator 1))
[ 98.406424] ? __pfx_hidp_session_wake_function (net/bluetooth/hidp/core.c:1251)
[ 98.406453] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)
[ 98.406476] ? trace_hardirqs_on (kernel/trace/trace_preemptirq.c:79 (discriminator 1))
[ 98.406499] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)
[ 98.406523] ? kthread (kernel/kthread.c:433)
[ 98.406539] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)
[ 98.406565] ? kthread (kernel/kthread.c:433)
[ 98.406581] ? __pfx_hidp_session_thread (net/bluetooth/hidp/core.c:1264)
[ 98.406610] kthread (kernel/kthread.c:467)
[ 98.406627] ? __pfx_kthread (kernel/kthread.c:412)
[ 98.406645] ret_from_fork (arch/x86/kernel/process.c:164)
[ 98.406674] ? __pfx_ret_from_fork (arch/x86/kernel/process.c:153)
[ 98.406704] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)
[ 98.406728] ? __pfx_kthread (kernel/kthread.c:412)
[ 98.406747] ret_from_fork_asm (arch/x86/entry/entry_64.S:258)
[ 98.406774] </TASK>
[ 98.406780]
[ 98.433693] The buggy address belongs to the physical page:
[ 98.434405] page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff888113ee7c40 pfn:0x113ee4
[ 98.435557] flags: 0x200000000000000(node=0|zone=2)
[ 98.436198] raw: 0200000000000000 ffffea0004244308 ffff8881f6f3ebc0 0000000000000000
[ 98.437195] raw: ffff888113ee7c40 0000000000000000 00000000ffffffff 0000000000000000
[ 98.438115] page dumped because: kasan: bad access detected
[ 98.438951]
[ 98.439211] Memory state around the buggy address:
[ 98.439871] ffff888113ee3f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 98.440714] ffff888113ee4000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
[ 98.441580] >ffff888113ee4080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
[ 98.442458] ^
[ 98.443011] ffff888113ee4100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
[ 98.443889] ffff888113ee4180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
[ 98.444768] ==================================================================
[ 98.445719] Disabling lock debugging due to kernel taint
[ 98.448074] l2cap_conn_free: freeing conn ffff88810c22b400
[ 98.450012] CPU: 1 UID: 0 PID: 1430 Comm: khidpd_00050004 Tainted: G B 7.0.0-rc1-dirty #14 PREEMPT(lazy)
[ 98.450040] Tainted: [B]=BAD_PAGE
[ 98.450047] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-debian-1.17.0-1 04/01/2014
[ 98.450059] Call Trace:
[ 98.450065] <TASK>
[ 98.450071] dump_stack_lvl (lib/dump_stack.c:122)
[ 98.450099] l2cap_conn_free (net/bluetooth/l2cap_core.c:1808)
[ 98.450125] l2cap_conn_put (net/bluetooth/l2cap_core.c:1822)
[ 98.450154] session_free (net/bluetooth/hidp/core.c:990)
[ 98.450181] hidp_session_thread (net/bluetooth/hidp/core.c:1307)
[ 98.450213] ? __pfx_hidp_session_thread (net/bluetooth/hidp/core.c:1264)
[ 98.450271] ? kthread (kernel/kthread.c:433)
[ 98.450293] ? __pfx_hidp_session_wake_function (net/bluetooth/hidp/core.c:1251)
[ 98.450339] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)
[ 98.450368] ? find_held_lock (kernel/locking/lockdep.c:5350 (discriminator 1))
[ 98.450406] ? __pfx_hidp_session_wake_function (net/bluetooth/hidp/core.c:1251)
[ 98.450442] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)
[ 98.450471] ? trace_hardirqs_on (kernel/trace/trace_preemptirq.c:79 (discriminator 1))
[ 98.450499] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)
[ 98.450528] ? kthread (kernel/kthread.c:433)
[ 98.450547] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)
[ 98.450578] ? kthread (kernel/kthread.c:433)
[ 98.450598] ? __pfx_hidp_session_thread (net/bluetooth/hidp/core.c:1264)
[ 98.450637] kthread (kernel/kthread.c:467)
[ 98.450657] ? __pfx_kthread (kernel/kthread.c:412)
[ 98.450680] ret_from_fork (arch/x86/kernel/process.c:164)
[ 98.450715] ? __pfx_ret_from_fork (arch/x86/kernel/process.c:153)
[ 98.450752] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)
[ 98.450782] ? __pfx_kthread (kernel/kthread.c:412)
[ 98.450804] ret_from_fork_asm (arch/x86/entry/entry_64.S:258)
[ 98.450836] </TASK>

Fixes: b4f34d8d9d26 ("Bluetooth: hidp: add new session-management helpers")
Reported-by: soufiane el hachmi <kilwa10@gmail.com>
Tested-by: soufiane el hachmi <kilwa10@gmail.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/bluetooth/hidp/core.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/net/bluetooth/hidp/core.c b/net/bluetooth/hidp/core.c
index 6724adce615b6..e0e4003815500 100644
--- a/net/bluetooth/hidp/core.c
+++ b/net/bluetooth/hidp/core.c
@@ -986,7 +986,8 @@ static void session_free(struct kref *ref)
skb_queue_purge(&session->intr_transmit);
fput(session->intr_sock->file);
fput(session->ctrl_sock->file);
- l2cap_conn_put(session->conn);
+ if (session->conn)
+ l2cap_conn_put(session->conn);
kfree(session);
}

@@ -1164,6 +1165,15 @@ static void hidp_session_remove(struct l2cap_conn *conn,

down_write(&hidp_session_sem);

+ /* Drop L2CAP reference immediately to indicate that
+ * l2cap_unregister_user() shall not be called as it is already
+ * considered removed.
+ */
+ if (session->conn) {
+ l2cap_conn_put(session->conn);
+ session->conn = NULL;
+ }
+
hidp_session_terminate(session);

cancel_work_sync(&session->dev_init);
@@ -1301,7 +1311,9 @@ static int hidp_session_thread(void *arg)
* Instead, this call has the same semantics as if user-space tried to
* delete the session.
*/
- l2cap_unregister_user(session->conn, &session->user);
+ if (session->conn)
+ l2cap_unregister_user(session->conn, &session->user);
+
hidp_session_put(session);

module_put_and_kthread_exit(0);
--
2.51.0