CVE-2021-47005: linux kernel Null Dereference — Fix

Description

In the Linux kernel, the following vulnerability has been resolved: PCI: endpoint: Fix NULL pointer dereference for ->get_features() get_features ops of pci_epc_ops may return NULL, causing NULL pointer dereference in pci_epf_test_alloc_space function. Let us add a check for pci_epc_feature pointer in pci_epf_test_bind before we access it to avoid any such NULL pointer dereference and return -ENOTSUPP in case pci_epc_feature is not found. When the patch is not applied and EPC features is not implemented in the platform driver, we see the following dump due to kernel NULL pointer dereference. Call trace: pci_epf_test_bind+0xf4/0x388 pci_epf_bind+0x3c/0x80 pci_epc_epf_link+0xa8/0xcc configfs_symlink+0x1a4/0x48c vfs_symlink+0x104/0x184 do_symlinkat+0x80/0xd4 __arm64_sys_symlinkat+0x1c/0x24 el0_svc_common.constprop.3+0xb8/0x170 el0_svc_handler+0x70/0x88 el0_svc+0x8/0x640 Code: d2800581 b9403ab9 f9404ebb 8b394f60 (f9400400) ---[ end trace a438e3c5a24f9df0 ]---

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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	5.1 — 5.10.38
linux	linux_kernel	5.11 — 5.11.22
linux	linux_kernel	5.12 — 5.12.5

References

Advisories & Patches

https://git.kernel.org/stable/c/0169d4f0bee44fdfef908c13ed21fcb326c38695 https://git.kernel.org/stable/c/6613bc2301ba291a1c5a90e1dc24cf3edf223c03 https://git.kernel.org/stable/c/679ebad058b8168f10e63876d63b0877fd2fe784 https://git.kernel.org/stable/c/bbed83d7060e07a5d309104d25a00f0a24441428 https://git.kernel.org/stable/c/0169d4f0bee44fdfef908c13ed21fcb326c38695 https://git.kernel.org/stable/c/6613bc2301ba291a1c5a90e1dc24cf3edf223c03 https://git.kernel.org/stable/c/679ebad058b8168f10e63876d63b0877fd2fe784 https://git.kernel.org/stable/c/bbed83d7060e07a5d309104d25a00f0a24441428

Frequently Asked Questions

What is CVE-2021-47005? +

In the Linux kernel, the following vulnerability has been resolved: PCI: endpoint: Fix NULL pointer dereference for ->get_features() get_features ops of pci_epc_ops may return NULL, causing NULL pointer dereference in pci_epf_test_alloc_space function. Let us add a check for pci_epc_feature pointer in pci_epf_test_bind before we access it to avoid any such NULL pointer dereference and return -ENOTSUPP in case pci_epc_feature is not found. When the patch is not applied and EPC features is not implemented in the platform driver, we see the following dump due to kernel NULL pointer dereference. Call trace: pci_epf_test_bind+0xf4/0x388 pci_epf_bind+0x3c/0x80 pci_epc_epf_link+0xa8/0xcc configfs_symlink+0x1a4/0x48c vfs_symlink+0x104/0x184 do_symlinkat+0x80/0xd4 __arm64_sys_symlinkat+0x1c/0x24 el0_svc_common.constprop.3+0xb8/0x170 el0_svc_handler+0x70/0x88 el0_svc+0x8/0x640 Code: d2800581 b9403ab9 f9404ebb 8b394f60 (f9400400) ---[ end trace a438e3c5a24f9df0 ]--- It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2021-47005? +

CVE-2021-47005 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-2021-47005? +

CVE-2021-47005 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-2021-47005? +

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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