This is a note to let you know that I've just added the patch titled
tee: amdtee: fix use-after-free vulnerability in amdtee_close_session
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
tee-amdtee-fix-use-after-free-vulnerability-in-amdtee_close_session.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From f4384b3e54ea813868bb81a861bf5b2406e15d8f Mon Sep 17 00:00:00 2001
From: Rijo Thomas <Rijo-john.Thomas@xxxxxxx>
Date: Fri, 29 Sep 2023 12:30:24 +0530
Subject: tee: amdtee: fix use-after-free vulnerability in amdtee_close_session
From: Rijo Thomas <Rijo-john.Thomas@xxxxxxx>
commit f4384b3e54ea813868bb81a861bf5b2406e15d8f upstream.
There is a potential race condition in amdtee_close_session that may
cause use-after-free in amdtee_open_session. For instance, if a session
has refcount == 1, and one thread tries to free this session via:
kref_put(&sess->refcount, destroy_session);
the reference count will get decremented, and the next step would be to
call destroy_session(). However, if in another thread,
amdtee_open_session() is called before destroy_session() has completed
execution, alloc_session() may return 'sess' that will be freed up
later in destroy_session() leading to use-after-free in
amdtee_open_session.
To fix this issue, treat decrement of sess->refcount and removal of
'sess' from session list in destroy_session() as a critical section, so
that it is executed atomically.
Fixes: 757cc3e9ff1d ("tee: add AMD-TEE driver")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Rijo Thomas <Rijo-john.Thomas@xxxxxxx>
Reviewed-by: Sumit Garg <sumit.garg@xxxxxxxxxx>
Signed-off-by: Jens Wiklander <jens.wiklander@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/tee/amdtee/core.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
--- a/drivers/tee/amdtee/core.c
+++ b/drivers/tee/amdtee/core.c
@@ -217,12 +217,12 @@ unlock:
return rc;
}
+/* mutex must be held by caller */
static void destroy_session(struct kref *ref)
{
struct amdtee_session *sess = container_of(ref, struct amdtee_session,
refcount);
- mutex_lock(&session_list_mutex);
list_del(&sess->list_node);
mutex_unlock(&session_list_mutex);
kfree(sess);
@@ -272,7 +272,8 @@ int amdtee_open_session(struct tee_conte
if (arg->ret != TEEC_SUCCESS) {
pr_err("open_session failed %d\n", arg->ret);
handle_unload_ta(ta_handle);
- kref_put(&sess->refcount, destroy_session);
+ kref_put_mutex(&sess->refcount, destroy_session,
+ &session_list_mutex);
goto out;
}
@@ -290,7 +291,8 @@ int amdtee_open_session(struct tee_conte
pr_err("reached maximum session count %d\n", TEE_NUM_SESSIONS);
handle_close_session(ta_handle, session_info);
handle_unload_ta(ta_handle);
- kref_put(&sess->refcount, destroy_session);
+ kref_put_mutex(&sess->refcount, destroy_session,
+ &session_list_mutex);
rc = -ENOMEM;
goto out;
}
@@ -331,7 +333,7 @@ int amdtee_close_session(struct tee_cont
handle_close_session(ta_handle, session_info);
handle_unload_ta(ta_handle);
- kref_put(&sess->refcount, destroy_session);
+ kref_put_mutex(&sess->refcount, destroy_session, &session_list_mutex);
return 0;
}
Patches currently in stable-queue which might be from Rijo-john.Thomas@xxxxxxx are
queue-6.1/tee-amdtee-fix-use-after-free-vulnerability-in-amdtee_close_session.patch
