#VU17910 NULL pointer dereference in Linux kernel - CVE-2019-9213

Vulnerability identifier: #VU17910

Vulnerability risk: Low

CVSSv4.0: 6.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:A/U:Clear]

CVE-ID: CVE-2019-9213

CWE-ID: CWE-476

Exploitation vector: Local

Exploit availability: Yes

Vulnerable software:
Linux kernel
Operating systems & Components / Operating system

Vendor: Linux Foundation

Description

The vulnerability allows a local user to perform a denial of service (DoS) attack.

The vulnerability exists due to a NULL pointer dreference error in expand_downwards() in mm/mmap.c that does not check for the mmap minimum address, which makes it easier for attackers to exploit kernel NULL pointer dereferences on non-SMAP platforms. This is related to a capability check for the wrong task. A local user can perform a denial of service (DoS) attack.

Mitigation
Install update from vendor's website.

Vulnerable software versions

Linux kernel: 4.9 - 4.9.161, 4.14 - 4.19.26, 4.20.1 - 4.20.13

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External links
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=0a1d52994d440e21def1c2174932410b4f2a98a1
https://bugs.chromium.org/p/project-zero/issues/detail?id=1792
https://cdn.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.14.105
https://cdn.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.19.27
https://cdn.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.20.14
https://cdn.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.9.162
https://github.com/torvalds/linux/commit/0a1d52994d440e21def1c2174932410b4f2a98a1

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Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability. However, a fully functional exploit for this vulnerability is available.