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    SubjectRe: [PATCH] optee: Suppress false positive kmemleak report in optee_handle_rpc()
    On Mon, Dec 06, 2021 at 08:05:33PM +0800, Xiaolei Wang wrote:
    > We observed the following kmemleak report:
    > unreferenced object 0xffff000007904500 (size 128):
    > comm "swapper/0", pid 1, jiffies 4294892671 (age 44.036s)
    > hex dump (first 32 bytes):
    > 00 47 90 07 00 00 ff ff 60 00 c0 ff 00 00 00 00 .G......`.......
    > 60 00 80 13 00 80 ff ff a0 00 00 00 00 00 00 00 `...............
    > backtrace:
    > [<000000004c12b1c7>] kmem_cache_alloc+0x1ac/0x2f4
    > [<000000005d23eb4f>] tee_shm_alloc+0x78/0x230
    > [<00000000794dd22c>] optee_handle_rpc+0x60/0x6f0
    > [<00000000d9f7c52d>] optee_do_call_with_arg+0x17c/0x1dc
    > [<00000000c35884da>] optee_open_session+0x128/0x1ec
    > [<000000001748f2ff>] tee_client_open_session+0x28/0x40
    > [<00000000aecb5389>] optee_enumerate_devices+0x84/0x2a0
    > [<000000003df18bf1>] optee_probe+0x674/0x6cc
    > [<000000003a4a534a>] platform_drv_probe+0x54/0xb0
    > [<000000000c51ce7d>] really_probe+0xe4/0x4d0
    > [<000000002f04c865>] driver_probe_device+0x58/0xc0
    > [<00000000b485397d>] device_driver_attach+0xc0/0xd0
    > [<00000000c835f0df>] __driver_attach+0x84/0x124
    > [<000000008e5a429c>] bus_for_each_dev+0x70/0xc0
    > [<000000001735e8a8>] driver_attach+0x24/0x30
    > [<000000006d94b04f>] bus_add_driver+0x104/0x1ec
    >
    > This is not a memory leak because we pass the share memory pointer
    > to secure world and would get it from secure world before releasing it.
    >
    > Signed-off-by: Xiaolei Wang <xiaolei.wang@windriver.com>
    > ---
    > drivers/tee/optee/smc_abi.c | 2 ++
    > 1 file changed, 2 insertions(+)
    >
    > diff --git a/drivers/tee/optee/smc_abi.c b/drivers/tee/optee/smc_abi.c
    > index 6196d7c3888f..cf2e3293567d 100644
    > --- a/drivers/tee/optee/smc_abi.c
    > +++ b/drivers/tee/optee/smc_abi.c
    > @@ -23,6 +23,7 @@
    > #include "optee_private.h"
    > #include "optee_smc.h"
    > #include "optee_rpc_cmd.h"
    > +#include <linux/kmemleak.h>
    > #define CREATE_TRACE_POINTS
    > #include "optee_trace.h"
    >
    > @@ -783,6 +784,7 @@ static void optee_handle_rpc(struct tee_context *ctx,
    > param->a4 = 0;
    > param->a5 = 0;
    > }
    > + kmemleak_not_leak(shm);

    Eventually this pointer will be freed below with the call to tee_shm_free().
    I assume than once the memory is freed it's not execused from being a leak
    any longer. Is that correct?

    Thanks,
    Jens

    > break;
    > case OPTEE_SMC_RPC_FUNC_FREE:
    > shm = reg_pair_to_ptr(param->a1, param->a2);
    > --
    > 2.25.1
    >

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