CVE-2022-50206: linux kernel Null Dereference — Fix

Description

In the Linux kernel, the following vulnerability has been resolved: arm64: fix oops in concurrently setting insn_emulation sysctls emulation_proc_handler() changes table->data for proc_dointvec_minmax and can generate the following Oops if called concurrently with itself: | Unable to handle kernel NULL pointer dereference at virtual address 0000000000000010 | Internal error: Oops: 96000006 [#1] SMP | Call trace: | update_insn_emulation_mode+0xc0/0x148 | emulation_proc_handler+0x64/0xb8 | proc_sys_call_handler+0x9c/0xf8 | proc_sys_write+0x18/0x20 | __vfs_write+0x20/0x48 | vfs_write+0xe4/0x1d0 | ksys_write+0x70/0xf8 | __arm64_sys_write+0x20/0x28 | el0_svc_common.constprop.0+0x7c/0x1c0 | el0_svc_handler+0x2c/0xa0 | el0_svc+0x8/0x200 To fix this issue, keep the table->data as &insn->current_mode and use container_of() to retrieve the insn pointer. Another mutex is used to protect against the current_mode update but not for retrieving insn_emulation as table->data is no longer changing.

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CVSS v3.1 Score

5.5

MEDIUM

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Weakness Type (CWE)

CWE-476 CWE-476

Affected Products

Vendor	Product	Versions
linux	linux_kernel	< 4.14.291
linux	linux_kernel	4.15 — 4.19.256
linux	linux_kernel	4.20 — 5.4.211
linux	linux_kernel	5.5 — 5.10.137
linux	linux_kernel	5.11 — 5.15.61
linux	linux_kernel	5.16 — 5.18.18
linux	linux_kernel	5.19 — 5.19.2

References

Advisories & Patches

https://git.kernel.org/stable/c/04549063d5701976034d8c2bfda3d3a8cbf0409f https://git.kernel.org/stable/c/07022e07017ee5540f5559b0aeb916e8383c1e1a https://git.kernel.org/stable/c/353b4673d01c512303c45cf2346f630cda73b5c9 https://git.kernel.org/stable/c/6a2fd114678d7fc1b5a0f8865ae98f1c17787455 https://git.kernel.org/stable/c/9d5fec6ba2e4117d196a8259ab54615ffe562460 https://git.kernel.org/stable/c/af483947d472eccb79e42059276c4deed76f99a6 https://git.kernel.org/stable/c/b51881b1da57fe9877125dfdd0aac5172958fcfd https://git.kernel.org/stable/c/cc69ef95988b9ef2fc730ec452a7441efb90ef5e

Frequently Asked Questions

What is CVE-2022-50206? +

In the Linux kernel, the following vulnerability has been resolved: arm64: fix oops in concurrently setting insn_emulation sysctls emulation_proc_handler() changes table->data for proc_dointvec_minmax and can generate the following Oops if called concurrently with itself: | Unable to handle kernel NULL pointer dereference at virtual address 0000000000000010 | Internal error: Oops: 96000006 [#1] SMP | Call trace: | update_insn_emulation_mode+0xc0/0x148 | emulation_proc_handler+0x64/0xb8 | proc_sys_call_handler+0x9c/0xf8 | proc_sys_write+0x18/0x20 | __vfs_write+0x20/0x48 | vfs_write+0xe4/0x1d0 | ksys_write+0x70/0xf8 | __arm64_sys_write+0x20/0x28 | el0_svc_common.constprop.0+0x7c/0x1c0 | el0_svc_handler+0x2c/0xa0 | el0_svc+0x8/0x200 To fix this issue, keep the table->data as &insn->current_mode and use container_of() to retrieve the insn pointer. Another mutex is used to protect against the current_mode update but not for retrieving insn_emulation as table->data is no longer changing. It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2022-50206? +

CVE-2022-50206 has a CVSS v3.1 score of 5.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2022-50206? +

CVE-2022-50206 affects products from linux, specifically: linux_kernel. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2022-50206? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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CVE-2022-50206