From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Jan Beulich <JBeulich@suse.com>,
xen-devel <xen-devel@lists.xenproject.org>
Subject: Re: [PATCH 3/4] x86emul: drop pointless and add useful default cases
Date: Thu, 23 Jun 2016 11:44:47 +0100 [thread overview]
Message-ID: <7ea1b9fa-9e42-002e-d970-b27bd459ed16@citrix.com> (raw)
In-Reply-To: <5767F68A02000078000F6AD1@prv-mh.provo.novell.com>
On 20/06/16 12:58, Jan Beulich wrote:
> @@ -3845,10 +3834,11 @@ x86_emulate(
> goto push;
> case 7:
> generate_exception_if(1, EXC_UD, -1);
> - default:
> - goto cannot_emulate;
> }
> break;
> +
> + default:
> + BUG();
These introduce DoS vulnerabilities if there is indeed a path to default.
Could I recommend instead a one-time printk() dumping the instruction
stream which lead to here, an ASSERT_UNREACHABLE(), and a goto
cannot_emulate?
That way, a production build won't crash.
~Andrew
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next prev parent reply other threads:[~2016-06-23 10:44 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-20 11:44 [PATCH 0/4] x86: instruction emulator adjustments Jan Beulich
2016-06-20 11:57 ` [PATCH RESEND 1/4] x86emul: support MOVBE and CRC32 Jan Beulich
2016-06-23 10:27 ` Andrew Cooper
2016-06-20 11:58 ` [PATCH 2/4] x86emul: use (locally) consistent exit mechanisms Jan Beulich
2016-06-23 10:36 ` Andrew Cooper
2016-06-23 12:27 ` Jan Beulich
2016-06-20 11:58 ` [PATCH 3/4] x86emul: drop pointless and add useful default cases Jan Beulich
2016-06-23 10:44 ` Andrew Cooper [this message]
2016-06-23 12:28 ` Jan Beulich
2016-06-20 11:59 ` [PATCH 4/4] x86emul: fold local variables Jan Beulich
2016-06-23 10:31 ` Andrew Cooper
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