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ksmbd: fix race condition from parallel smb2 lock requests

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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>
This commit is contained in:
Namjae Jeon 2023-10-04 18:31:03 +09:00 committed by Steve French
parent 7ca9da7d87
commit 75ac9a3dd6
1 changed files with 1 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
fs/smb/server/smb2pdu.c
View File

@ -7038,10 +7038,6 @@ skip:
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);
@ -7072,9 +7068,6 @@ skip:
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) {
@ -7094,19 +7087,16 @@ skip:
}
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;