Bug 568621 - (CVE-2010-2653) CVE-2010-2653 kvm: vulnerability in the hvc_console code that gets exposed via the new virtio_console functionality
CVE-2010-2653 kvm: vulnerability in the hvc_console code that gets exposed vi...
Product: Security Response
Classification: Other
Component: vulnerability (Show other bugs)
All Linux
high Severity high
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Assigned To: Red Hat Product Security
: Security
Depends On: 568624 579408
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Reported: 2010-02-26 01:56 EST by Eugene Teo (Security Response)
Modified: 2016-03-29 06:14 EDT (History)
10 users (show)

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Fixed In Version:
Doc Type: Bug Fix
Doc Text:
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Clone Of:
Last Closed: 2016-03-29 06:14:38 EDT
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RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: ---

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Description Eugene Teo (Security Response) 2010-02-26 01:56:28 EST
Description of problem:
Alan pointed out a race in the code where hvc_remove is invoked. The recent virtio_console work is the first user of hvc_remove().

Alan describes it thus:

The hvc_console assumes that a close and remove call can't occur at the same time.

In addition tty_hangup(tty) is problematic as tty_hangup is asynchronous itself....

So this can happen

        hvc_close                               hvc_remove
        hung up ? - no
                                                tty = hp->tty
        hp->tty = NULL
        notify del
        kref_put the hvc struct
        close completes
        tty is destroyed
                                                tty_hangup dead tty
                                                tty->ops will be NULL

This patch adds some tty krefs and also converts to using tty_vhangup().

Reported-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Amit Shah <amit.shah@redhat.com>
CC: Alan Cox <alan@lxorguk.ukuu.org.uk>
CC: linuxppc-dev@ozlabs.org
CC: Rusty Russell <rusty@rustcorp.com.au>

Alan, how does this version look?

I've tested with multiple virtio_console ports.

There's some other bug in the hvc_remove code that's unrelated: hot-removal of one console port results in all other hvc consoles to stop working. I'll look at that once this is finalised.

 drivers/char/hvc_console.c |   31 +++++++++++++++++++++----------
 1 files changed, 21 insertions(+), 10 deletions(-)

Comment 7 Eugene Teo (Security Response) 2010-03-04 03:58:36 EST
Comment 8 Eugene Teo (Security Response) 2010-03-04 04:06:13 EST

Not vulnerable. This issue did not affect the versions of KVM as shipped with Red Hat Enterprise Linux 5 as it does not contain the patch that introduced this vulnerability.
Comment 9 Kyle McMartin 2010-03-05 07:52:09 EST
OK, thanks guys, I committed the fix for this to F-13 branch this morning.
Comment 18 Mike McCune 2016-03-28 19:33:48 EDT
This bug was accidentally moved from POST to MODIFIED via an error in automation, please see mmccune@redhat.com with any questions

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