Re: [PATCH] tee: fix missing shm reference cleanup in tee_ioctl_supp_recv

Hi Sumit,

Thanks, that makes sense.

I had been conservative about the possibility of num_params being updated by supp_recv backends, but looking again at the current paths, I agree that alloc_num_params is unnecessary here.

I'll drop that, rename the helper to free_params(), and send a v2.

Thanks, Qihang

On Fri, May 1, 2026 at 10:32 PM Sumit Garg sumit.garg@kernel.org wrote:

On Wed, Apr 29, 2026 at 07:32:19PM +0800, Qihang wrote:

...

params_from_user() acquires tee_shm references for MEMREF parameters and expects the caller to release those references with tee_shm_put() during cleanup.

tee_ioctl_open_session(), tee_ioctl_invoke(), and tee_ioctl_object_invoke() all do this, but tee_ioctl_supp_recv() only frees the parameter array and does not drop any acquired shared-memory references.

Fix this by using a common helper to release MEMREF references before freeing the parameter array, and apply it to tee_ioctl_supp_recv() as well.

Since supp_recv backends may update num_params, preserve the original allocated parameter count for cleanup.

Signed-off-by: Qihang q.h.hack.winter@gmail.com

drivers/tee/tee_core.c | 49 +++++++++++++++++++----------------------- 1 file changed, 22 insertions(+), 27 deletions(-)

diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c index ef9642d72672..adad1ea8e31b 100644 --- a/drivers/tee/tee_core.c +++ b/drivers/tee/tee_core.c @@ -530,6 +530,21 @@ static int params_to_user(struct tee_ioctl_param __user *uparams, return 0; }

+static void params_free_decref(struct tee_param *params, size_t num_params)

I would rather rename this API as free_params().

...

+{

• size_t n;
  

• if (!params)
  

•         return;
  

• for (n = 0; n < num_params; n++)
  

•         if (tee_param_is_memref(params + n) &&
  

•             params[n].u.memref.shm)
  

•                 tee_shm_put(params[n].u.memref.shm);
  

• kfree(params);
  

+}

static int tee_ioctl_open_session(struct tee_context *ctx, struct tee_ioctl_buf_data __user *ubuf) { @@ -595,16 +610,7 @@ static int tee_ioctl_open_session(struct tee_context *ctx, */ if (rc && have_session && ctx->teedev->desc->ops->close_session) ctx->teedev->desc->ops->close_session(ctx, arg.session);

• if (params) {
  

•         /* Decrease ref count for all valid shared memory pointers */
  

•         for (n = 0; n < arg.num_params; n++)
  

•                 if (tee_param_is_memref(params + n) &&
  

•                     params[n].u.memref.shm)
  

•                         tee_shm_put(params[n].u.memref.shm);
  

•         kfree(params);
  

• }
  

• params_free_decref(params, arg.num_params);
  return rc;
  

}

@@ -657,14 +663,7 @@ static int tee_ioctl_invoke(struct tee_context *ctx, } rc = params_to_user(uparams, arg.num_params, params); out:

• if (params) {
  

•         /* Decrease ref count for all valid shared memory pointers */
  

•         for (n = 0; n < arg.num_params; n++)
  

•                 if (tee_param_is_memref(params + n) &&
  

•                     params[n].u.memref.shm)
  

•                         tee_shm_put(params[n].u.memref.shm);
  

•         kfree(params);
  

• }
  

• params_free_decref(params, arg.num_params);
  return rc;
  

}

@@ -716,14 +715,7 @@ static int tee_ioctl_object_invoke(struct tee_context *ctx, } rc = params_to_user(uparams, arg.num_params, params); out:

• if (params) {
  

•         /* Decrease ref count for all valid shared memory pointers */
  

•         for (n = 0; n < arg.num_params; n++)
  

•                 if (tee_param_is_memref(params + n) &&
  

•                     params[n].u.memref.shm)
  

•                         tee_shm_put(params[n].u.memref.shm);
  

•         kfree(params);
  

• }
  

• params_free_decref(params, arg.num_params);
  return rc;
  

}

@@ -822,6 +814,7 @@ static int tee_ioctl_supp_recv(struct tee_context *ctx, struct tee_iocl_supp_recv_arg __user *uarg; struct tee_param *params; u32 num_params;

• u32 alloc_num_params;
  u32 func;
  
  if (!ctx->teedev->desc->ops->supp_recv)
  

@@ -838,6 +831,8 @@ static int tee_ioctl_supp_recv(struct tee_context *ctx, if (get_user(num_params, &uarg->num_params)) return -EFAULT;

• alloc_num_params = num_params;
  

Why is this needed? Shouldn't the updated num_params will point to size of params array?

-Sumit

...

• if (size_add(sizeof(*uarg), TEE_IOCTL_PARAM_SIZE(num_params)) != buf.buf_len)
          return -EINVAL;
  
  

@@ -861,7 +856,7 @@ static int tee_ioctl_supp_recv(struct tee_context *ctx,

  rc = params_to_supp(ctx, uarg->params, num_params, params);

out:

• kfree(params);
  

• params_free_decref(params, alloc_num_params);
  return rc;
  

}

-- 2.39.5 (Apple Git-154)