NULL pointer dereference in Linux kernel

1) NULL pointer dereference

EUVDB-ID: #VU17910

Risk: Low

CVSSv3.1: 5.1 [CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H/E:F/RL:O/RC:C]

CVE-ID: CVE-2019-9213

CWE-ID: CWE-476 - NULL Pointer Dereference

Exploit availability: Yes

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 - 4.20.13

External links

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

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.