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Date: Thu, 23 May 2019 00:52:17 +1000
From: Wade Mealing <wmealing@...hat.com>
To: oss-security@...ts.openwall.com
Subject: CVE-2019-10142 linux kernel: integer overflow in ioctl handling of
fsl hypervisor
Gday,
>From the upstream git commit:
"The "param.count" value is a u64 that comes from the user. The code later
in the function assumes that param.count is at least one and if it's not
then it leads to an Oops when we dereference the ZERO_SIZE_PTR. Also the
addition can have an integer overflow which would lead us to allocate a
smaller "pages" array than required. I can't immediately tell what the
possible run times implications are, but it's safest to prevent the
overflow."
At this time Red Hat products are not affected this code is not built as
the CONFIG_FSL_HV_MANAGER build option is not enabled by default. Device
(/dev/fsl-hv) ownership and permissions which prevent unprivileged users
from being able to exploit this without some elevated permissions (I think
this will default to user: root group:root with 0660 mask) however some
Linux distributions may use udev to set this to non root ownership or
another group. In the default configuration, a user who is sufficiently
privileged to exploit this is likely able to attack the system without it.
I open the discussion and note the CVE listed above for discussions that
may reference this patch and perhaps save someone some time in
investigation.
Red Hat bugzilla:
https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2019-10142
Upstream fix:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=6a024330650e24556b8a18cc654ad00cfecf6c6c
--
Wade Mealing
Product Security - Kernel, RHCE
Red Hat
<https://www.redhat.com>
wmealing@...hat.com
<https://red.ht/sig>
TRIED. TESTED. TRUSTED. <https://redhat.com/trusted>
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