Re: [PATCH v2] tee: fix missing shm reference cleanup in tee_ioctl_supp_recv

Hi Qihang,

On Tue, May 5, 2026 at 5:30 PM Qihang q.h.hack.winter@gmail.com 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.

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

v2:

• rename helper to free_params()
• drop alloc_num_params and use num_params directly

drivers/tee/tee_core.c | 46 +++++++++++++++++------------------------- 1 file changed, 19 insertions(+), 27 deletions(-)

diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c index ef9642d72672..8cdf2ec7e74f 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 free_params(struct tee_param *params, size_t num_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);
  

•   }
  

•   free_params(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);
  

•   }
  

•   free_params(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);
  

•   }
  

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

}

@@ -861,7 +853,7 @@ static int tee_ioctl_supp_recv(struct tee_context *ctx,

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

out:

•   kfree(params);
  

•   free_params(params, num_params);
  

This doesn't work. The supp_recv() callback is special compared to open_session(), invoke_func(), and object_invoke_func() callbacks. supp_recv() replaces the supplied parameters with other parameters. Eventually inserted memrefs are reference-counted separately, and adding it here too would only add unnecessary updates (supp_recv() would need to increase them, only so they can be decreased here). However, I think a comment before the call to supp_recv() to remind us of that would be nice.

However, there's a bug that needs to be fixed if params_from_user() fails. One way of dealing with that is: rc = params_from_user(ctx, params, num_params, uarg->params); if (rc) { free_params(params, num_params); return rc; }

and then keep the end of tee_ioctl_supp_recv() unchanged.

Cheers, Jens

    return rc;

}

-- 2.39.5 (Apple Git-154)