From: Ben Hutchings <ben@decadent.org.uk>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: akpm@linux-foundation.org,
"Steve Rutherford" <srutherford@google.com>,
"Dmitry Vyukov" <dvyukov@google.com>,
"Paolo Bonzini" <pbonzini@redhat.com>
Subject: [PATCH 3.16 05/12] KVM: x86: Introduce segmented_write_std
Date: Fri, 24 Feb 2017 12:10:01 +0000 [thread overview]
Message-ID: <lsq.1487938201.498286716@decadent.org.uk> (raw)
In-Reply-To: <lsq.1487938201.529166958@decadent.org.uk>
3.16.41-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Steve Rutherford <srutherford@google.com>
commit 129a72a0d3c8e139a04512325384fe5ac119e74d upstream.
Introduces segemented_write_std.
Switches from emulated reads/writes to standard read/writes in fxsave,
fxrstor, sgdt, and sidt. This fixes CVE-2017-2584, a longstanding
kernel memory leak.
Since commit 283c95d0e389 ("KVM: x86: emulate FXSAVE and FXRSTOR",
2016-11-09), which is luckily not yet in any final release, this would
also be an exploitable kernel memory *write*!
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Fixes: 96051572c819194c37a8367624b285be10297eca
Fixes: 283c95d0e3891b64087706b344a4b545d04a6e62
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Steve Rutherford <srutherford@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
[bwh: Backported to 3.16: drop changes to em_fxsave(), em_fxrstor()]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -744,6 +744,20 @@ static int segmented_read_std(struct x86
return ctxt->ops->read_std(ctxt, linear, data, size, &ctxt->exception);
}
+static int segmented_write_std(struct x86_emulate_ctxt *ctxt,
+ struct segmented_address addr,
+ void *data,
+ unsigned int size)
+{
+ int rc;
+ ulong linear;
+
+ rc = linearize(ctxt, addr, size, true, &linear);
+ if (rc != X86EMUL_CONTINUE)
+ return rc;
+ return ctxt->ops->write_std(ctxt, linear, data, size, &ctxt->exception);
+}
+
/*
* Fetch the next byte of the instruction being emulated which is pointed to
* by ctxt->_eip, then increment ctxt->_eip.
@@ -3268,8 +3282,8 @@ static int emulate_store_desc_ptr(struct
}
/* Disable writeback. */
ctxt->dst.type = OP_NONE;
- return segmented_write(ctxt, ctxt->dst.addr.mem,
- &desc_ptr, 2 + ctxt->op_bytes);
+ return segmented_write_std(ctxt, ctxt->dst.addr.mem,
+ &desc_ptr, 2 + ctxt->op_bytes);
}
static int em_sgdt(struct x86_emulate_ctxt *ctxt)
next prev parent reply other threads:[~2017-02-24 13:09 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-24 12:10 [PATCH 3.16 00/12] 3.16.41-rc1 review Ben Hutchings
2017-02-24 12:10 ` [PATCH 3.16 11/12] dccp: fix freeing skb too early for IPV6_RECVPKTINFO Ben Hutchings
2017-02-24 12:10 ` [PATCH 3.16 10/12] ipv4: keep skb->dst around in presence of IP options Ben Hutchings
2017-02-24 12:10 ` [PATCH 3.16 04/12] KVM: x86: fix emulation of "MOV SS, null selector" Ben Hutchings
2017-02-24 12:10 ` Ben Hutchings [this message]
2017-02-24 12:10 ` [PATCH 3.16 02/12] kvm: nVMX: Allow L1 to intercept software exceptions (#BP and #OF) Ben Hutchings
2017-02-24 12:10 ` [PATCH 3.16 01/12] mnt: Add a per mount namespace limit on the number of mounts Ben Hutchings
2017-02-24 12:10 ` [PATCH 3.16 03/12] ext4: validate s_first_meta_bg at mount time Ben Hutchings
2017-02-24 12:10 ` [PATCH 3.16 07/12] USB: serial: kl5kusb105: fix line-state error handling Ben Hutchings
2017-02-24 12:10 ` [PATCH 3.16 08/12] tmpfs: clear S_ISGID when setting posix ACLs Ben Hutchings
2017-02-24 12:10 ` [PATCH 3.16 06/12] selinux: fix off-by-one in setprocattr Ben Hutchings
2017-02-24 12:10 ` [PATCH 3.16 09/12] ip6_gre: fix ip6gre_err() invalid reads Ben Hutchings
2017-02-24 12:10 ` [PATCH 3.16 12/12] tcp: avoid infinite loop in tcp_splice_read() Ben Hutchings
2017-02-24 16:19 ` [PATCH 3.16 00/12] 3.16.41-rc1 review Guenter Roeck
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=lsq.1487938201.498286716@decadent.org.uk \
--to=ben@decadent.org.uk \
--cc=akpm@linux-foundation.org \
--cc=dvyukov@google.com \
--cc=linux-kernel@vger.kernel.org \
--cc=pbonzini@redhat.com \
--cc=srutherford@google.com \
--cc=stable@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®