Bug 1427239 (CVE-2017-5669) - CVE-2017-5669 kernel: Shmat allows mmap null page protection bypass
Summary: CVE-2017-5669 kernel: Shmat allows mmap null page protection bypass
Status: CLOSED NOTABUG
Alias: CVE-2017-5669
Product: Security Response
Classification: Other
Component: vulnerability   
(Show other bugs)
Version: unspecified
Hardware: All
OS: Linux
low
low
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard: impact=low,public=20170120,reported=2...
Keywords: Security
Depends On:
Blocks: 1427241
TreeView+ depends on / blocked
 
Reported: 2017-02-27 16:28 UTC by Andrej Nemec
Modified: 2017-03-17 15:01 UTC (History)
35 users (show)

Fixed In Version:
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Doc Text:
The do_shmat function in ipc/shm.c in the Linux kernel, through 4.9.12, does not restrict the address calculated by a certain rounding operation. This allows privileged local users to map page zero and, consequently, bypass a protection mechanism that exists for the mmap system call. This is possible by making crafted shmget and shmat system calls in a privileged context.
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Clone Of:
Environment:
Last Closed: 2017-03-16 16:49:01 UTC
Type: ---
Regression: ---
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RHEL 7.3 requirements from Atomic Host:
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Description Andrej Nemec 2017-02-27 16:28:02 UTC
The do_shmat function in ipc/shm.c in the Linux kernel does not restrict the address calculated by a certain rounding operation, which allows local users to map page zero, and consequently bypass a protection mechanism that exists for the mmap system call, by making crafted shmget and shmat system calls in a privileged context.

Upstream bug:

https://bugzilla.kernel.org/show_bug.cgi?id=192931

Upstream patch:

https://github.com/torvalds/linux/commit/e1d35d4dc7f089e6c9c080d556feedf9c706f0c7

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=95e91b831f87ac8e1f8ed50c14d709089b4e01b8

Comment 1 Fedora Update System 2017-03-11 11:51:39 UTC
kernel-4.9.13-101.fc24 has been pushed to the Fedora 24 stable repository. If problems still persist, please make note of it in this bug report.

Comment 4 Vladis Dronov 2017-03-16 16:49:01 UTC
Statement:

This issue does not affect the Linux kernel packages as shipped with Red Hat Enterprise Linux 5, 6, 7 and Red Hat Enterprise MRG-2 as the flaw can only be exploited by a privileged user.


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