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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: KernelAssignee: 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 gentoo-dev Security 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 gentoo-dev Security 2020-03-02 21:53:07 UTC
Only affecting 5.4+
Comment 2 Thomas Deutschmann gentoo-dev Security 2020-03-02 21:55:24 UTC
We don't stabilize kernel sources for aarch64.