In service_callback path RCU dereferenced pointer struct vchiq_service
need to be accessed inside rcu read-critical section.
Accessing same with rcu_read_[lock/unlock] fixes the issue.
[ 32.201659] =============================
[ 32.201664] WARNING: suspicious RCU usage
[ 32.201670] 5.15.11-rt24-v8+ #3 Not tainted
[ 32.201680] -----------------------------
[ 32.201685] drivers/staging/vc04_services/interface/vchiq_arm/vchiq_core.h:529 suspicious rcu_dereference_check() usage!
[ 32.201695]
[ 32.201695] other info that might help us debug this:
[ 32.201695]
[ 32.201700]
[ 32.201700] rcu_scheduler_active = 2, debug_locks = 1
[ 32.201708] no locks held by vchiq-slot/0/98.
[ 32.201715]
[ 32.201715] stack backtrace:
[ 32.201723] CPU: 1 PID: 98 Comm: vchiq-slot/0 Not tainted 5.15.11-rt24-v8+ #3
[ 32.201733] Hardware name: Raspberry Pi 4 Model B Rev 1.4 (DT)
[ 32.201739] Call trace:
[ 32.201742] dump_backtrace+0x0/0x1b8
[ 32.201772] show_stack+0x20/0x30
[ 32.201784] dump_stack_lvl+0x8c/0xb8
[ 32.201799] dump_stack+0x18/0x34
[ 32.201808] lockdep_rcu_suspicious+0xe4/0xf8
[ 32.201817] service_callback+0x124/0x400
[ 32.201830] slot_handler_func+0xf60/0x1e20
[ 32.201839] kthread+0x19c/0x1a8
[ 32.201849] ret_from_fork+0x10/0x20
Signed-off-by: Padmanabha Srinivasaiah <treasure4paddy@xxxxxxxxx>
---
Changes in v2:
RCU dereferenced pointer need to be accessed inside rcu
read-side critical section.
.../vc04_services/interface/vchiq_arm/vchiq_arm.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
index 6759a6261500..8ddd400ab2c3 100644
--- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
+++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
@@ -1053,24 +1053,30 @@ service_callback(enum vchiq_reason reason, struct vchiq_header *header,
struct vchiq_service *service;
struct vchiq_instance *instance;
bool skip_completion = false;
+ unsigned int localport;
DEBUG_INITIALISE(g_state.local);
DEBUG_TRACE(SERVICE_CALLBACK_LINE);
+ rcu_read_lock();
service = handle_to_service(handle);
- if (WARN_ON(!service))
+ if (WARN_ON(!service)) {
+ rcu_read_unlock();
return VCHIQ_SUCCESS;
+ }
user_service = (struct user_service *)service->base.userdata;
instance = user_service->instance;
+ localport = service->localport;
+ rcu_read_unlock();
if (!instance || instance->closing)
return VCHIQ_SUCCESS;
vchiq_log_trace(vchiq_arm_log_level,
"%s - service %lx(%d,%p), reason %d, header %lx, instance %lx, bulk_userdata %lx",
- __func__, (unsigned long)user_service, service->localport,
+ __func__, (unsigned long)user_service, (int)localport,
user_service->userdata, reason, (unsigned long)header,
(unsigned long)instance, (unsigned long)bulk_userdata);
--
2.17.1
