From 019d0b4cc2b6da03dac724682fdd97e59bc34c77 Mon Sep 17 00:00:00 2001 From: Namjae Jeon Date: Tue, 3 Oct 2023 10:52:02 +0900 Subject: [PATCH] ksmbd: fix race condition from parallel smb2 lock requests There is a race condtion 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. Signed-off-by: Namjae Jeon --- smb2pdu.c | 12 +----------- 1 file changed, 1 insertion(+), 11 deletions(-) diff --git a/smb2pdu.c b/smb2pdu.c index 868df32ed..519b98a59 100644 --- a/smb2pdu.c +++ b/smb2pdu.c @@ -7645,10 +7645,6 @@ 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); @@ -7679,9 +7675,6 @@ 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) { @@ -7701,19 +7694,16 @@ 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;