diff options
| author | Nicholas Carlini <nicholas@carlini.com> | 2026-03-09 08:29:49 +0900 |
|---|---|---|
| committer | Steve French <stfrench@microsoft.com> | 2026-03-17 21:45:29 -0500 |
| commit | 5258572aa5fd5a7ed01b123b28241e0281b6fb9b (patch) | |
| tree | 0544e60318d4d9f4d6b7e0e5be14921f3c6ff109 /fs/smb | |
| parent | f338e77383789c0cae23ca3d48adcc5e9e137e3c (diff) | |
ksmbd: fix share_conf UAF in tree_conn disconnect
__ksmbd_tree_conn_disconnect() drops the share_conf reference before
checking tree_conn->refcount. When someone uses SMB3 multichannel and
binds two connections to one session, a SESSION_LOGOFF on connection A
calls ksmbd_conn_wait_idle(conn) which only drains connection A's
request counter, not connection B's. This means there's a race condition:
requests already dispatched on connection B hold tree_conn references via
work->tcon. The disconnect path frees share_conf while those requests
are still walking work->tcon->share_conf, causing a use-after-free.
This fix combines the share_conf put with the tree_conn free so it
only happens when the last reference is dropped.
Fixes: b39a1833cc4a ("ksmbd: fix use-after-free in ksmbd_tree_connect_put under concurrency")
Signed-off-by: Nicholas Carlini <nicholas@carlini.com>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Diffstat (limited to 'fs/smb')
| -rw-r--r-- | fs/smb/server/mgmt/tree_connect.c | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/fs/smb/server/mgmt/tree_connect.c b/fs/smb/server/mgmt/tree_connect.c index a72d7e42a6c2..58e5b8592da4 100644 --- a/fs/smb/server/mgmt/tree_connect.c +++ b/fs/smb/server/mgmt/tree_connect.c @@ -102,8 +102,10 @@ out_error: void ksmbd_tree_connect_put(struct ksmbd_tree_connect *tcon) { - if (atomic_dec_and_test(&tcon->refcount)) + if (atomic_dec_and_test(&tcon->refcount)) { + ksmbd_share_config_put(tcon->share_conf); kfree(tcon); + } } static int __ksmbd_tree_conn_disconnect(struct ksmbd_session *sess, @@ -113,10 +115,11 @@ static int __ksmbd_tree_conn_disconnect(struct ksmbd_session *sess, ret = ksmbd_ipc_tree_disconnect_request(sess->id, tree_conn->id); ksmbd_release_tree_conn_id(sess, tree_conn->id); - ksmbd_share_config_put(tree_conn->share_conf); ksmbd_counter_dec(KSMBD_COUNTER_TREE_CONNS); - if (atomic_dec_and_test(&tree_conn->refcount)) + if (atomic_dec_and_test(&tree_conn->refcount)) { + ksmbd_share_config_put(tree_conn->share_conf); kfree(tree_conn); + } return ret; } |