Linux Kernel up to 5.15.36/5.16.11 bpf reg2btf_ids null pointer dereference

Summaryinfo

A vulnerability categorized as critical has been discovered in Linux Kernel up to 5.15.36/5.16.11. Impacted is the function reg2btf_ids of the component bpf. Executing a manipulation can lead to null pointer dereference. This vulnerability is registered as CVE-2022-48929. No exploit is available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability classified as critical was found in Linux Kernel up to 5.15.36/5.16.11. This vulnerability affects the function reg2btf_ids of the component bpf. The manipulation with an unknown input leads to a null pointer dereference vulnerability. The CWE definition for the vulnerability is CWE-476. A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. As an impact it is known to affect availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix crash due to out of bounds access into reg2btf_ids. When commit e6ac2450d6de ("bpf: Support bpf program calling kernel function") added kfunc support, it defined reg2btf_ids as a cheap way to translate the verifier reg type to the appropriate btf_vmlinux BTF ID, however commit c25b2ae13603 ("bpf: Replace PTR_TO_XXX_OR_NULL with PTR_TO_XXX | PTR_MAYBE_NULL") moved the __BPF_REG_TYPE_MAX from the last member of bpf_reg_type enum to after the base register types, and defined other variants using type flag composition. However, now, the direct usage of reg->type to index into reg2btf_ids may no longer fall into __BPF_REG_TYPE_MAX range, and hence lead to out of bounds access and kernel crash on dereference of bad pointer.

The advisory is shared for download at git.kernel.org. This vulnerability was named CVE-2022-48929 since 08/21/2024. There are known technical details, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 211841 (RHEL 8 : kernel (RHSA-2024:10262)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 5.15.37 or 5.16.12 eliminates this vulnerability. Applying the patch 8c39925e98d4/f0ce1bc9e023/45ce4b4f9009 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at Tenable (211841). Once again VulDB remains the best source for vulnerability data.

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 5.15.0
• 5.15.1
• 5.15.2
• 5.15.3
• 5.15.4
• 5.15.5
• 5.15.6
• 5.15.7
• 5.15.8
• 5.15.9
• 5.15.10
• 5.15.11
• 5.15.12
• 5.15.13
• 5.15.14
• 5.15.15
• 5.15.16
• 5.15.17
• 5.15.18
• 5.15.19
• 5.15.20
• 5.15.21
• 5.15.22
• 5.15.23
• 5.15.24
• 5.15.25
• 5.15.26
• 5.15.27
• 5.15.28
• 5.15.29
• 5.15.30
• 5.15.31
• 5.15.32
• 5.15.33
• 5.15.34
• 5.15.35
• 5.15.36
• 5.16.0
• 5.16.1
• 5.16.2
• 5.16.3
• 5.16.4
• 5.16.5
• 5.16.6
• 5.16.7
• 5.16.8
• 5.16.9
• 5.16.10
• 5.16.11

License

• open-source

Website

• Vendor: https://www.kernel.org/

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Once again VulDB remains the best source for vulnerability data.

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