[ Upstream commit 75ac9a3dd65f7eab4d12b0a0f744234b5300a491 ]
There is a race condition issue between parallel smb2 lock request.
Time + Thread A | Thread A smb2_lock | smb2_lock | insert smb_lock to lock_list | spin_unlock(&work->conn->llist_lock) | | | spin_lock(&conn->llist_lock); | kfree(cmp_lock); | // UAF! | list_add(&smb_lock->llist, &rollback_list) +
This patch swaps the line for adding the smb lock to the rollback list and adding the lock list of connection to fix the race issue.
Reported-by: luosili rootlab@huawei.com Signed-off-by: Namjae Jeon linkinjeon@kernel.org Signed-off-by: Steve French stfrench@microsoft.com --- fs/ksmbd/smb2pdu.c | 12 +----------- 1 file changed, 1 insertion(+), 11 deletions(-)
diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c index 924b561e8c81..560d81799647 100644 --- a/fs/ksmbd/smb2pdu.c +++ b/fs/ksmbd/smb2pdu.c @@ -7040,10 +7040,6 @@ int smb2_lock(struct ksmbd_work *work)
ksmbd_debug(SMB, "would have to wait for getting lock\n"); - spin_lock(&work->conn->llist_lock); - list_add_tail(&smb_lock->clist, - &work->conn->lock_list); - spin_unlock(&work->conn->llist_lock); list_add(&smb_lock->llist, &rollback_list);
argv = kmalloc(sizeof(void *), GFP_KERNEL); @@ -7074,9 +7070,6 @@ int smb2_lock(struct ksmbd_work *work)
if (work->state != KSMBD_WORK_ACTIVE) { list_del(&smb_lock->llist); - spin_lock(&work->conn->llist_lock); - list_del(&smb_lock->clist); - spin_unlock(&work->conn->llist_lock); locks_free_lock(flock);
if (work->state == KSMBD_WORK_CANCELLED) { @@ -7096,19 +7089,16 @@ int smb2_lock(struct ksmbd_work *work) }
list_del(&smb_lock->llist); - spin_lock(&work->conn->llist_lock); - list_del(&smb_lock->clist); - spin_unlock(&work->conn->llist_lock); release_async_work(work); goto retry; } else if (!rc) { + list_add(&smb_lock->llist, &rollback_list); spin_lock(&work->conn->llist_lock); list_add_tail(&smb_lock->clist, &work->conn->lock_list); list_add_tail(&smb_lock->flist, &fp->lock_list); spin_unlock(&work->conn->llist_lock); - list_add(&smb_lock->llist, &rollback_list); ksmbd_debug(SMB, "successful in taking lock\n"); } else { goto out;