6.6-stable review patch. If anyone has any objections, please let me know.
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From: Sean Heelan seanheelan@gmail.com
commit e86e9134e1d1c90a960dd57f59ce574d27b9a124 upstream.
Setting sess->user = NULL was introduced to fix the dangling pointer created by ksmbd_free_user. However, it is possible another thread could be operating on the session and make use of sess->user after it has been passed to ksmbd_free_user but before sess->user is set to NULL.
Cc: stable@vger.kernel.org Signed-off-by: Sean Heelan seanheelan@gmail.com Acked-by: Namjae Jeon linkinjeon@kernel.org Signed-off-by: Steve French stfrench@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/smb/server/auth.c | 14 +++++++++++++- fs/smb/server/smb2pdu.c | 5 ----- 2 files changed, 13 insertions(+), 6 deletions(-)
--- a/fs/smb/server/auth.c +++ b/fs/smb/server/auth.c @@ -546,7 +546,19 @@ int ksmbd_krb5_authenticate(struct ksmbd retval = -ENOMEM; goto out; } - sess->user = user; + + if (!sess->user) { + /* First successful authentication */ + sess->user = user; + } else { + if (!ksmbd_compare_user(sess->user, user)) { + ksmbd_debug(AUTH, "different user tried to reuse session\n"); + retval = -EPERM; + ksmbd_free_user(user); + goto out; + } + ksmbd_free_user(user); + }
memcpy(sess->sess_key, resp->payload, resp->session_key_len); memcpy(out_blob, resp->payload + resp->session_key_len, --- a/fs/smb/server/smb2pdu.c +++ b/fs/smb/server/smb2pdu.c @@ -1599,11 +1599,6 @@ static int krb5_authenticate(struct ksmb if (prev_sess_id && prev_sess_id != sess->id) destroy_previous_session(conn, sess->user, prev_sess_id);
- if (sess->state == SMB2_SESSION_VALID) { - ksmbd_free_user(sess->user); - sess->user = NULL; - } - retval = ksmbd_krb5_authenticate(sess, in_blob, in_len, out_blob, &out_len); if (retval) {