From 6e30c0e10210c714f3d4453dc258d4abcc70364e Mon Sep 17 00:00:00 2001 From: Sean Heelan Date: Mon, 7 Apr 2025 11:26:50 +0000 Subject: [PATCH] ksmbd: Fix dangling pointer in krb_authenticate commit 1e440d5b25b7efccb3defe542a73c51005799a5f upstream. 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 Acked-by: Namjae Jeon Signed-off-by: Steve French Signed-off-by: Greg Kroah-Hartman --- fs/smb/server/smb2pdu.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c index 7fea86edc717..129517a0c5c7 100644 --- a/fs/smb/server/smb2pdu.c +++ b/fs/smb/server/smb2pdu.c @@ -1599,8 +1599,10 @@ 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);