diff options
| author | Padmanabha Srinivasaiah <treasure4paddy@gmail.com> | 2021-12-31 20:54:03 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-01-25 16:36:34 +0100 |
| commit | 0cea730cac824edf78ffd3302938ed5fe2b9d50d (patch) | |
| tree | aa52eeb211fe1d23f915c0c672a8101559472262 /drivers/staging | |
| parent | e783362eb54cd99b2cac8b3a9aeac942e6f6ac07 (diff) | |
| download | linux-0cea730cac824edf78ffd3302938ed5fe2b9d50d.tar.bz2 | |
staging: vc04_services: Fix RCU dereference check
In service_callback path RCU dereferenced pointer struct vchiq_service
need to be accessed inside rcu read-critical section.
Also userdata/user_service part of vchiq_service is accessed around
different synchronization mechanism, getting an extra reference to a
pointer keeps sematics simpler and avoids prolonged graceperiod.
Accessing vchiq_service with rcu_read_[lock/unlock] fixes below 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
Tested-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Padmanabha Srinivasaiah <treasure4paddy@gmail.com>
Link: https://lore.kernel.org/r/20211231195406.5479-1-treasure4paddy@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/staging')
| -rw-r--r-- | drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c | 20 |
1 files changed, 18 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..3a2e4582db8e 100644 --- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c +++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c @@ -1058,15 +1058,27 @@ service_callback(enum vchiq_reason reason, struct vchiq_header *header, 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; - if (!instance || instance->closing) + if (!instance || instance->closing) { + rcu_read_unlock(); return VCHIQ_SUCCESS; + } + + /* + * As hopping around different synchronization mechanism, + * taking an extra reference results in simpler implementation. + */ + vchiq_service_get(service); + rcu_read_unlock(); vchiq_log_trace(vchiq_arm_log_level, "%s - service %lx(%d,%p), reason %d, header %lx, instance %lx, bulk_userdata %lx", @@ -1097,6 +1109,7 @@ service_callback(enum vchiq_reason reason, struct vchiq_header *header, bulk_userdata); if (status != VCHIQ_SUCCESS) { DEBUG_TRACE(SERVICE_CALLBACK_LINE); + vchiq_service_put(service); return status; } } @@ -1105,10 +1118,12 @@ service_callback(enum vchiq_reason reason, struct vchiq_header *header, if (wait_for_completion_interruptible(&user_service->remove_event)) { vchiq_log_info(vchiq_arm_log_level, "%s interrupted", __func__); DEBUG_TRACE(SERVICE_CALLBACK_LINE); + vchiq_service_put(service); return VCHIQ_RETRY; } else if (instance->closing) { vchiq_log_info(vchiq_arm_log_level, "%s closing", __func__); DEBUG_TRACE(SERVICE_CALLBACK_LINE); + vchiq_service_put(service); return VCHIQ_ERROR; } DEBUG_TRACE(SERVICE_CALLBACK_LINE); @@ -1137,6 +1152,7 @@ service_callback(enum vchiq_reason reason, struct vchiq_header *header, header = NULL; } DEBUG_TRACE(SERVICE_CALLBACK_LINE); + vchiq_service_put(service); if (skip_completion) return VCHIQ_SUCCESS; |