Bug 711126 (CVE-2020-9391)

Summary:	kernel: brk discards top byte of addresses on aarch64, causing heap corruption in glibc malloc (CVE-2020-9391)
Product:	Gentoo Security	Reporter:	Sam James <sam>
Component:	Kernel	Assignee:	Gentoo Kernel Security <security-kernel>
Status:	RESOLVED UPSTREAM
Severity:	trivial
Priority:	Normal
Version:	unspecified
Hardware:	ARM64
OS:	Linux
URL:	https://www.openwall.com/lists/oss-security/2020/02/25/6
Whiteboard:	~3 [upstream/ebuild]
Package list:		Runtime testing required:	---

Description Sam James archtester

2020-03-01 01:20:46 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."

Affects: aarch64/arm64

Patch: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=dcde237319e626d1ec3c9d8b7613032f0fd4663a

Comment 1 Thomas Deutschmann (RETIRED) gentoo-dev

2020-03-02 21:53:07 UTC

Only affecting 5.4+

Comment 2 Thomas Deutschmann (RETIRED) gentoo-dev

2020-03-02 21:55:24 UTC

We don't stabilize kernel sources for aarch64.