Messages in this thread | | | Date | Fri, 10 Dec 2021 09:10:53 +0100 | Subject | Re: [PATCH] optee: Suppress false positive kmemleak report in optee_handle_rpc() | From | Jerome Forissier <> |
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+CC Jens, Etienne
On 12/10/21 06:00, Sumit Garg wrote: > On Fri, 10 Dec 2021 at 09:42, Wang, Xiaolei <Xiaolei.Wang@windriver.com> wrote: >> >> -----Original Message----- >> From: Sumit Garg <sumit.garg@linaro.org> >> Sent: Thursday, December 9, 2021 7:41 PM >> To: Wang, Xiaolei <Xiaolei.Wang@windriver.com> >> Cc: jens.wiklander@linaro.org; op-tee@lists.trustedfirmware.org; linux-kernel@vger.kernel.org >> Subject: Re: [PATCH] optee: Suppress false positive kmemleak report in optee_handle_rpc() >> >> [Please note: This e-mail is from an EXTERNAL e-mail address] >> >> On Mon, 6 Dec 2021 at 17:35, Xiaolei Wang <xiaolei.wang@windriver.com> 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. >> >>> How about if it's actually a memory leak caused by the secure world? >>> An example being secure world just allocates kernel memory via OPTEE_SMC_RPC_FUNC_ALLOC and doesn't free it via OPTEE_SMC_RPC_FUNC_FREE. >> >>> IMO, we need to cross-check optee-os if it's responsible for leaking kernel memory. >> >> Hi sumit, >> >> You mean we need to check whether there is a real memleak, >> If being secure world just allocate kernel memory via OPTEE_SMC_PRC_FUNC_ALLOC and until the end, there is no free >> It via OPTEE_SMC_PRC_FUNC_FREE, then we should judge it as a memory leak, wo need to judge whether it is caused by secure os? > > Yes. AFAICT, optee-os should allocate shared memory to communicate > with tee-supplicant. So once the communication is done, the underlying > shared memory should be freed. I can't think of any scenario where > optee-os should keep hold-off shared memory indefinitely.
I believe it can happen when OP-TEE's CFG_PREALLOC_RPC_CACHE is y. See the config file [1] and the commit which introduced this config [2].
[1] https://github.com/OP-TEE/optee_os/blob/3.15.0/mk/config.mk#L709 [2] https://github.com/OP-TEE/optee_os/commit/8887663248ad
-- Jerome
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