From: Sean Heelan <seanheelan@gmail.com>
Date: Mon, 7 Apr 2025 11:26:50 +0000 (+0000)
Subject: ksmbd: Fix dangling pointer in krb_authenticate
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=1e440d5b25b7efccb3defe542a73c51005799a5f;p=users%2Fjedix%2Flinux-maple.git

ksmbd: Fix dangling pointer in krb_authenticate

krb_authenticate frees sess->user and does not set the pointer
to NULL. It calls ksmbd_krb5_authenticate to reinitialise
sess->user but that function may return without doing so. If
that happens then smb2_sess_setup, which calls krb_authenticate,
will be accessing free'd memory when it later uses sess->user.

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>
---

diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c
index d24d95d15d876..57839f9708bb6 100644
--- a/fs/smb/server/smb2pdu.c
+++ b/fs/smb/server/smb2pdu.c
@@ -1602,8 +1602,10 @@ static int krb5_authenticate(struct ksmbd_work *work,
 	if (prev_sess_id && prev_sess_id != sess->id)
 		destroy_previous_session(conn, sess->user, prev_sess_id);
 
-	if (sess->state == SMB2_SESSION_VALID)
+	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);