From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F14AD1D9A66 for ; Wed, 18 Mar 2026 01:35:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773797735; cv=none; b=VZrx1Dn8cdC+mD84FwtTC4Sbw6AuzEA/ryAY+iooce4BPlXQCB588zKhO64CkH8ZhwYQE0iy5+M2e6HKR3p39osA30Ex1OX36gJO150bb0pW66yt1gkZvs7FKmOj8lgUUE52Rib4eMW2e0CEeBz6mCn7oTIRAsDXPGBLXq4Z6dA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773797735; c=relaxed/simple; bh=2svO7ANRoavkXX03zVdJ6rQ13oBZ4sElxrn9G2qa3hY=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=W4vJzZwHI5dO1mI2eXbrJGWEYLZMyZ1/QWIBe6/NKbnR9spXBFUKq26GZ/OgMrt4lv5VXMa/8ZapSTknpSUmFXaxo5aUHptgxjZD33PpDxtXvys8ywOmwr1H5q5uCALTyCRzmpRzdLppk7lQQjZ/Pl/be32Ce1zB1+udJZB85mY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=R2r5YQBR; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="R2r5YQBR" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1773797733; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=CqFzHcb2df96RmQfDBr72f2by0y/t+p/YTVOoCXpzdE=; b=R2r5YQBR7MKscjnBIyyHIDkzMbk4TzjCnPIKXu5JnpzYyXf6g9bRspO4FZCoDol/5/W+z2 FqtyVQ9K7lOcCa1+AjCY1rUKlwVYtF0vxykrUK2Js5iyGkD4wBsJq6M7gkJpw9rR2aS0Nr OrWiFxuVBac9irbMDxw+yMDok9DAmHQ= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-687-5D8pHsBeMcWUJOkStvAmWg-1; Tue, 17 Mar 2026 21:35:29 -0400 X-MC-Unique: 5D8pHsBeMcWUJOkStvAmWg-1 X-Mimecast-MFC-AGG-ID: 5D8pHsBeMcWUJOkStvAmWg_1773797728 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 2156F180034E; Wed, 18 Mar 2026 01:35:28 +0000 (UTC) Received: from localhost (unknown [10.72.116.147]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id B42E51800351; Wed, 18 Mar 2026 01:35:26 +0000 (UTC) From: Ming Lei To: Greg Kroah-Hartman , stable@vger.kernel.org Cc: linux-block@vger.kernel.org, Sasha Levin , Mehul Rao , Ming Lei , Jens Axboe Subject: [PATCH 6.18.y] ublk: fix NULL pointer dereference in ublk_ctrl_set_size() Date: Wed, 18 Mar 2026 09:35:17 +0800 Message-ID: <20260318013517.3124637-1-ming.lei@redhat.com> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 From: Mehul Rao commit 25966fc097691e5c925ad080f64a2f19c5fd940a upstream. ublk_ctrl_set_size() unconditionally dereferences ub->ub_disk via set_capacity_and_notify() without checking if it is NULL. ub->ub_disk is NULL before UBLK_CMD_START_DEV completes (it is only assigned in ublk_ctrl_start_dev()) and after UBLK_CMD_STOP_DEV runs (ublk_detach_disk() sets it to NULL). Since the UBLK_CMD_UPDATE_SIZE handler performs no state validation, a user can trigger a NULL pointer dereference by sending UPDATE_SIZE to a device that has been added but not yet started, or one that has been stopped. Fix this by checking ub->ub_disk under ub->mutex before dereferencing it, and returning -ENODEV if the disk is not available. Fixes: 98b995660bff ("ublk: Add UBLK_U_CMD_UPDATE_SIZE") Cc: stable@vger.kernel.org Signed-off-by: Mehul Rao Reviewed-by: Ming Lei Signed-off-by: Jens Axboe Signed-off-by: Ming Lei --- drivers/block/ublk_drv.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c index 965460d4fc76..2729b1556e81 100644 --- a/drivers/block/ublk_drv.c +++ b/drivers/block/ublk_drv.c @@ -3604,15 +3604,22 @@ static int ublk_ctrl_get_features(const struct ublksrv_ctrl_cmd *header) return 0; } -static void ublk_ctrl_set_size(struct ublk_device *ub, const struct ublksrv_ctrl_cmd *header) +static int ublk_ctrl_set_size(struct ublk_device *ub, const struct ublksrv_ctrl_cmd *header) { struct ublk_param_basic *p = &ub->params.basic; u64 new_size = header->data[0]; + int ret = 0; mutex_lock(&ub->mutex); + if (!ub->ub_disk) { + ret = -ENODEV; + goto out; + } p->dev_sectors = new_size; set_capacity_and_notify(ub->ub_disk, p->dev_sectors); +out: mutex_unlock(&ub->mutex); + return ret; } struct count_busy { @@ -3902,8 +3909,7 @@ static int ublk_ctrl_uring_cmd(struct io_uring_cmd *cmd, ret = ublk_ctrl_end_recovery(ub, header); break; case UBLK_CMD_UPDATE_SIZE: - ublk_ctrl_set_size(ub, header); - ret = 0; + ret = ublk_ctrl_set_size(ub, header); break; case UBLK_CMD_QUIESCE_DEV: ret = ublk_ctrl_quiesce_dev(ub, header); -- 2.47.0