CVE-2021-47631: linux kernel Null Dereference — Fix

Description

In the Linux kernel, the following vulnerability has been resolved: ARM: davinci: da850-evm: Avoid NULL pointer dereference With newer versions of GCC, there is a panic in da850_evm_config_emac() when booting multi_v5_defconfig in QEMU under the palmetto-bmc machine: Unable to handle kernel NULL pointer dereference at virtual address 00000020 pgd = (ptrval) [00000020] *pgd=00000000 Internal error: Oops: 5 [#1] PREEMPT ARM Modules linked in: CPU: 0 PID: 1 Comm: swapper Not tainted 5.15.0 #1 Hardware name: Generic DT based system PC is at da850_evm_config_emac+0x1c/0x120 LR is at do_one_initcall+0x50/0x1e0 The emac_pdata pointer in soc_info is NULL because davinci_soc_info only gets populated on davinci machines but da850_evm_config_emac() is called on all machines via device_initcall(). Move the rmii_en assignment below the machine check so that it is only dereferenced when running on a supported SoC.

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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	2.6.33 — 4.9.311
linux	linux_kernel	4.10 — 4.14.276
linux	linux_kernel	4.15 — 4.19.239
linux	linux_kernel	4.20 — 5.4.190
linux	linux_kernel	5.5 — 5.10.112
linux	linux_kernel	5.11 — 5.15.35
linux	linux_kernel	5.16 — 5.17.4
linux	linux_kernel	All
linux	linux_kernel	All

References

Advisories & Patches

https://git.kernel.org/stable/c/0940795c6834fbe7705acc5c3d4b2f7a5f67527a https://git.kernel.org/stable/c/0a312ec66a03133d28570f07bc52749ccfef54da https://git.kernel.org/stable/c/83a1cde5c74bfb44b49cb2a940d044bb2380f4ea https://git.kernel.org/stable/c/89931d4762572aaee6edbe5673d41f8082de110f https://git.kernel.org/stable/c/a12b356d45cbb6e8a1b718d1436b3d6239a862f3 https://git.kernel.org/stable/c/c06f476e5b74bcabb8c4a2fba55864a37e62843b https://git.kernel.org/stable/c/c5628533a3ece64235d04fe11ec44d2be99e423d https://git.kernel.org/stable/c/c64e2ed5cc376e137e572babfd2edc38b2cfb61b

Frequently Asked Questions

What is CVE-2021-47631? +

In the Linux kernel, the following vulnerability has been resolved: ARM: davinci: da850-evm: Avoid NULL pointer dereference With newer versions of GCC, there is a panic in da850_evm_config_emac() when booting multi_v5_defconfig in QEMU under the palmetto-bmc machine: Unable to handle kernel NULL pointer dereference at virtual address 00000020 pgd = (ptrval) [00000020] *pgd=00000000 Internal error: Oops: 5 [#1] PREEMPT ARM Modules linked in: CPU: 0 PID: 1 Comm: swapper Not tainted 5.15.0 #1 Hardware name: Generic DT based system PC is at da850_evm_config_emac+0x1c/0x120 LR is at do_one_initcall+0x50/0x1e0 The emac_pdata pointer in soc_info is NULL because davinci_soc_info only gets populated on davinci machines but da850_evm_config_emac() is called on all machines via device_initcall(). Move the rmii_en assignment below the machine check so that it is only dereferenced when running on a supported SoC. It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2021-47631? +

CVE-2021-47631 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-2021-47631? +

CVE-2021-47631 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-2021-47631? +

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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