Bug 1814237 (CVE-2020-9391) - CVE-2020-9391 kernel: brk discards top byte of addresses on aarch64 causing heap corruption in glibc malloc
Summary: CVE-2020-9391 kernel: brk discards top byte of addresses on aarch64 causing h...
Keywords:
Status: CLOSED NOTABUG
Alias: CVE-2020-9391
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 1797052 1814238
Blocks: 1805473
TreeView+ depends on / blocked
 
Reported: 2020-03-17 12:51 UTC by Guilherme de Almeida Suckevicz
Modified: 2021-02-16 20:27 UTC (History)
46 users (show)

Fixed In Version:
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Doc Text:
A heap corruption flaw was found in the Linux kernel on the AArch64 architecture. The top byte is ignored in the address passed to the brk system call, potentially moving the memory break downwards when the application expects it to move upwards. This has been observed to cause heap corruption within the GNU C Library malloc implementation. The highest threat from this vulnerability is to system availability.
Clone Of:
Environment:
Last Closed: 2020-03-23 16:32:17 UTC
Embargoed:

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Description Guilherme de Almeida Suckevicz 2020-03-17 12:51:08 UTC 
An issue was discovered in the Linux kernel 5.4 and 5.5 through 5.5.6 on the AArch64 architecture. It ignores the top byte in the address passed to the brk system call, potentially moving the memory break downwards when the application expects it to move upwards, aka CID-dcde237319e6. This has been observed to cause heap corruption with the GNU C Library malloc implementation.

References:
https://bugzilla.redhat.com/show_bug.cgi?id=1797052
http://www.openwall.com/lists/oss-security/2020/02/25/6

Upstream commit:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=dcde237319e626d1ec3c9d8b7613032f0fd4663a
Comment 1 Guilherme de Almeida Suckevicz 2020-03-17 12:52:26 UTC 
Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1814238]
Comment 4 Rohit Keshri 2020-03-20 12:18:19 UTC 
Mitigation:

Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.
Comment 5 Rohit Keshri 2020-03-20 12:19:26 UTC 
Statement:

The affected code was not introduced into any kernel versions shipped with Red Hat Enterprise Linux making this vulnerable not applicable to these platforms.
Comment 7 Product Security DevOps Team 2020-03-23 16:32:17 UTC 
This bug is now closed. Further updates for individual products will be reflected on the CVE page(s):

https://access.redhat.com/security/cve/cve-2020-9391
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