From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:42440 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751457AbdKFLG1 (ORCPT ); Mon, 6 Nov 2017 06:06:27 -0500 Received: from pps.filterd (m0098410.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id vA6B4kfw071571 for ; Mon, 6 Nov 2017 06:06:27 -0500 Received: from e06smtp14.uk.ibm.com (e06smtp14.uk.ibm.com [195.75.94.110]) by mx0a-001b2d01.pphosted.com with ESMTP id 2e2k2kag5n-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Mon, 06 Nov 2017 06:06:26 -0500 Received: from localhost by e06smtp14.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 6 Nov 2017 11:06:24 -0000 Subject: Re: FAILED: patch "[PATCH] KEYS: trusted: fix writing past end of buffer in" failed to apply to 4.9-stable tree From: Mimi Zohar To: gregkh@linuxfoundation.org, ebiggers@google.com, ben@decadent.org.uk, dhowells@redhat.com, james.l.morris@oracle.com, stable@vger.kernel.org Date: Mon, 06 Nov 2017 06:06:19 -0500 In-Reply-To: <150989148916639@kroah.com> References: <150989148916639@kroah.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Message-Id: <1509966379.3416.212.camel@linux.vnet.ibm.com> Sender: stable-owner@vger.kernel.org List-ID: Hi Greg, On Sun, 2017-11-05 at 15:18 +0100, gregkh@linuxfoundation.org wrote: > The patch below does not apply to the 4.9-stable tree. > If someone wants it applied there, or to any other stable or longterm > tree, then please email the backport, including the original git commit > id to . > > thanks, > > greg k-h This commit needs to prereq commit ee618b4619b7 "KEYS: trusted: sanitize all key material". Mimi > ------------------ original commit in Linus's tree ------------------ > > From a3c812f7cfd80cf51e8f5b7034f7418f6beb56c1 Mon Sep 17 00:00:00 2001 > From: Eric Biggers > Date: Thu, 2 Nov 2017 00:47:12 +0000 > Subject: [PATCH] KEYS: trusted: fix writing past end of buffer in > trusted_read() > > When calling keyctl_read() on a key of type "trusted", if the > user-supplied buffer was too small, the kernel ignored the buffer length > and just wrote past the end of the buffer, potentially corrupting > userspace memory. Fix it by instead returning the size required, as per > the documentation for keyctl_read(). > > We also don't even fill the buffer at all in this case, as this is > slightly easier to implement than doing a short read, and either > behavior appears to be permitted. It also makes it match the behavior > of the "encrypted" key type. > > Fixes: d00a1c72f7f4 ("keys: add new trusted key-type") > Reported-by: Ben Hutchings > Cc: # v2.6.38+ > Signed-off-by: Eric Biggers > Signed-off-by: David Howells > Reviewed-by: Mimi Zohar > Reviewed-by: James Morris > Signed-off-by: James Morris > > diff --git a/security/keys/trusted.c b/security/keys/trusted.c > index bd85315cbfeb..98aa89ff7bfd 100644 > --- a/security/keys/trusted.c > +++ b/security/keys/trusted.c > @@ -1147,20 +1147,21 @@ static long trusted_read(const struct key *key, char __user *buffer, > p = dereference_key_locked(key); > if (!p) > return -EINVAL; > - if (!buffer || buflen <= 0) > - return 2 * p->blob_len; > - ascii_buf = kmalloc(2 * p->blob_len, GFP_KERNEL); > - if (!ascii_buf) > - return -ENOMEM; > > - bufp = ascii_buf; > - for (i = 0; i < p->blob_len; i++) > - bufp = hex_byte_pack(bufp, p->blob[i]); > - if ((copy_to_user(buffer, ascii_buf, 2 * p->blob_len)) != 0) { > + if (buffer && buflen >= 2 * p->blob_len) { > + ascii_buf = kmalloc(2 * p->blob_len, GFP_KERNEL); > + if (!ascii_buf) > + return -ENOMEM; > + > + bufp = ascii_buf; > + for (i = 0; i < p->blob_len; i++) > + bufp = hex_byte_pack(bufp, p->blob[i]); > + if (copy_to_user(buffer, ascii_buf, 2 * p->blob_len) != 0) { > + kzfree(ascii_buf); > + return -EFAULT; > + } > kzfree(ascii_buf); > - return -EFAULT; > } > - kzfree(ascii_buf); > return 2 * p->blob_len; > } > >