From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793187553; b=o33kFr9oEVxHb+9M0GNLLA9ILHmA+qQY2zlu5ZAJceI9jYRv6pZ5qJZN/lwmSrzcos9+ h4IKVOMLgN4bVm0DisO3ZdWPmnTUpS7mgHyPP81b0guSq5yqZK/uU+ce6mFegd+6Ykgj+ CjsSme9AeWYD/EYo4dITDNX9BcGerw2xX2slX/wKqR566RkYlTtoLNlkkSJIIvbrM7RJ1 nsksGIshvrdRG9fneHpt9U2ZUy5gPsekuk+3n1wpqaAMRJ5rNqvF8YX1KZWk4lVs3Ma2f zEW2M62MOrOH5baEtzn4vIYzpBESWcjngH/mkvQoRpXiCC7MSyk4vJwj2d0uSDs+KYg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793187553; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: Reply-To:MIME-Version:Lines:X-Developer-Signature:X-Developer-Key: Content-Transfer-Encoding; bh=UigXQslvSRc9ehEqD9Go10oNONQVrtjjMrzYTErzFq8=; b=CgaR5+TAA7Q+hBTAGWaI8cjXEy33KO7E7VHaGRp7crAE+gjkGfUFWk+LWOohpxmFBPIc /wqJ6Kq1NpSTyAN38SHdrzW37jJYUlHF3inaTmL0fz+FOaRQyXMECfU+hYLeANPBglLGO N+YQoTRvHk7StFUOXFitHTY90bTcIOAMTKn6LypiM5/9NS++/ZxGWXkMplX54nD0ODUse iJzxrC29BUPDP2Fnhe1PshB1FYYx3x7/BmKVkU/n8iO3rhfpXwBmI3y3tpGstYnpfHgIl QXes8f9ISZcR1dCZ5E4uEmoVyWWhjiLpebvAQOlTeUUWzTD17785aQ0EdGIgrluDoJw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=ckRH3zn7; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 389CD606A32F for ; Wed, 28 Oct 2026 11:39:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=ckRH3zn7 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 75D801F01825; Wed, 28 Oct 2026 11:39:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793187553; bh=UigXQslvSRc9ehEqD9Go10oNONQVrtjjMrzYTErzFq8=; h=From:To:Cc:Subject:Date:Reply-To; b=ckRH3zn7wNTi28GIObkr0vOFNKxs7UkfCFmWEfU6jcFdugVIXBMvHsZSkhwwhlqE+ 2pPPu3UkqK8Tdix/C/+7DXm2O6RGcFgyKsi6cR96ETAPAWKDRLqvI3A3pL1Rn98NDi Flb3c3dIwz0PFg659s3XixreA+9f/+F2iCgvoJ1Y= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-99155: scsi: xen/scsifront: Check for a NULL shadow entry on a backend response Date: Wed, 28 Oct 2026 11:35:42 +0100 Message-ID: <2026102804-CVE-2026-99155-244e@gregkh> X-Mailer: git-send-email 2.56.0 Reply-To: , X-Mailing-List: linux-cve-announce@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2949; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=iw7u9L9mB3h0bzg3DoLcnCqVWixtI7oA9W+YsAZrE/0=; b=owGbwMvMwCRo6H6F97bub03G02pJDFkPz9+om3Noa6v4uTU2poZL+uMaDzq2zy85UdtXFiuqy v+wyVuqI5aFQZCJQVZMkeXLNp6j+ysOKXoZ2p6GmcPKBDKEgYtTACbS+51hfs6p+0v47hq0sf5K n+Fw9dhlbiXX2Qzzw/Y3LT9mvXMpd0vlkn878qMfJs8qBQA= X-Developer-Key: i=gregkh@linuxfoundation.org; a=openpgp; fpr=F4B60CC5BF78C2214A313DCB3147D40DDB2DFB29 Content-Transfer-Encoding: 8bit From: Greg Kroah-Hartman Description =========== In the Linux kernel, the following vulnerability has been resolved: scsi: xen/scsifront: Check for a NULL shadow entry on a backend response scsifront_do_response() validates the rqid in a backend response against VSCSIIF_MAX_REQS before using it to index info->shadow[], but then dereferences the entry to test ->inflight without checking that the slot is populated. Shadow slots are NULL before a command is submitted (the host private area is zeroed at allocation) and are reset to NULL in _scsifront_put_rqid() once a request completes, so an in-range rqid that does not correspond to an outstanding request makes the frontend dereference a NULL pointer. A malicious or buggy backend can thus crash the guest by returning a response whose rqid is in range but not in flight -- for example a spurious response before any command has been issued, or a duplicate of one already completed. The ring has only VSCSIIF_MAX_REQS (16) slots, so before the first command every in-range rqid selects a NULL slot. Reject a response whose shadow slot is not populated. The Linux kernel CVE team has assigned CVE-2026-99155 to this issue. Affected and fixed versions =========================== Issue introduced in 5.19 with commit 6d1c2f48f3fcf5f42967938c8ba6b42ac6b44b43 and fixed in 6.18.59 with commit 1d91ec793d6c80eca963d426e0da832d40a062df Issue introduced in 5.19 with commit 6d1c2f48f3fcf5f42967938c8ba6b42ac6b44b43 and fixed in 7.2.13 with commit 15791e57f57f7050014d08cfe239d4aa1e6b94b0 Issue introduced in 5.19 with commit 6d1c2f48f3fcf5f42967938c8ba6b42ac6b44b43 and fixed in 7.3 with commit 8c8222c255772713eb36cde695777a1fce224917 Please see https://www.kernel.org for a full list of currently supported kernel versions by the kernel community. Unaffected versions might change over time as fixes are backported to older supported kernel versions. The official CVE entry at https://cve.org/CVERecord/?id=CVE-2026-99155 will be updated if fixes are backported, please check that for the most up to date information about this issue. Affected files ============== The file(s) affected by this issue are: drivers/scsi/xen-scsifront.c Mitigation ========== The Linux kernel CVE team recommends that you update to the latest stable kernel version for this, and many other bugfixes. Individual changes are never tested alone, but rather are part of a larger kernel release. Cherry-picking individual commits is not recommended or supported by the Linux kernel community at all. If however, updating to the latest release is impossible, the individual changes to resolve this issue can be found at these commits: https://git.kernel.org/stable/c/1d91ec793d6c80eca963d426e0da832d40a062df https://git.kernel.org/stable/c/15791e57f57f7050014d08cfe239d4aa1e6b94b0 https://git.kernel.org/stable/c/8c8222c255772713eb36cde695777a1fce224917