[PATCH 5.9 103/252] tee: amdtee: synchronize access to shm list

Greg Kroah-Hartman
2020-11-23T13:14:11Z

From: Rijo Thomas <Rijo-john.Thomas@amd.com>

[ Upstream commit be353be27874f40837327d9a39e3ad2149ab66d3 ]

Synchronize access to shm or shared memory buffer list to prevent
race conditions due to concurrent updates to shared shm list by
multiple threads.

Fixes: 757cc3e9ff1d ("tee: add AMD-TEE driver")
Reviewed-by: Devaraj Rangasamy <Devaraj.Rangasamy@amd.com>
Signed-off-by: Rijo Thomas <Rijo-john.Thomas@amd.com>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/tee/amdtee/amdtee_private.h | 1 +
drivers/tee/amdtee/core.c | 8 ++++++++
2 files changed, 9 insertions(+)

diff --git a/drivers/tee/amdtee/amdtee_private.h b/drivers/tee/amdtee/amdtee_private.h
index 97df16a17285a..337c8d82f74eb 100644
--- a/drivers/tee/amdtee/amdtee_private.h
+++ b/drivers/tee/amdtee/amdtee_private.h
@@ -70,6 +70,7 @@ struct amdtee_session {
struct amdtee_context_data {
struct list_head sess_list;
struct list_head shm_list;
+ struct mutex shm_mutex; /* synchronizes access to @shm_list */
};

struct amdtee_driver_data {
diff --git a/drivers/tee/amdtee/core.c b/drivers/tee/amdtee/core.c
index ce61c68ec58cb..8a6a8f30bb427 100644
--- a/drivers/tee/amdtee/core.c
+++ b/drivers/tee/amdtee/core.c
@@ -42,6 +42,7 @@ static int amdtee_open(struct tee_context *ctx)

INIT_LIST_HEAD(&ctxdata->sess_list);
INIT_LIST_HEAD(&ctxdata->shm_list);
+ mutex_init(&ctxdata->shm_mutex);

ctx->data = ctxdata;
return 0;
@@ -85,6 +86,7 @@ static void amdtee_release(struct tee_context *ctx)
list_del(&sess->list_node);
release_session(sess);
}
+ mutex_destroy(&ctxdata->shm_mutex);
kfree(ctxdata);

ctx->data = NULL;
@@ -155,11 +157,13 @@ u32 get_buffer_id(struct tee_shm *shm)
struct amdtee_shm_data *shmdata;
u32 buf_id = 0;

+ mutex_lock(&ctxdata->shm_mutex);
list_for_each_entry(shmdata, &ctxdata->shm_list, shm_node)
if (shmdata->kaddr == shm->kaddr) {
buf_id = shmdata->buf_id;
break;
}
+ mutex_unlock(&ctxdata->shm_mutex);

return buf_id;
}
@@ -364,7 +368,9 @@ int amdtee_map_shmem(struct tee_shm *shm)
shmnode->kaddr = shm->kaddr;
shmnode->buf_id = buf_id;
ctxdata = shm->ctx->data;
+ mutex_lock(&ctxdata->shm_mutex);
list_add(&shmnode->shm_node, &ctxdata->shm_list);
+ mutex_unlock(&ctxdata->shm_mutex);

pr_debug("buf_id :[%x] kaddr[%p]\n", shmnode->buf_id, shmnode->kaddr);

@@ -385,12 +391,14 @@ void amdtee_unmap_shmem(struct tee_shm *shm)
handle_unmap_shmem(buf_id);

ctxdata = shm->ctx->data;
+ mutex_lock(&ctxdata->shm_mutex);
list_for_each_entry(shmnode, &ctxdata->shm_list, shm_node)
if (buf_id == shmnode->buf_id) {
list_del(&shmnode->shm_node);
kfree(shmnode);
break;
}
+ mutex_unlock(&ctxdata->shm_mutex);
}

int amdtee_invoke_func(struct tee_context *ctx,
--
2.27.0