CVE-2023-52447

MEDIUM
Published Feb 22, 2024 Modified May 12, 2026 CWE-416

Description

In the Linux kernel, the following vulnerability has been resolved: bpf: Defer the free of inner map when necessary When updating or deleting an inner map in map array or map htab, the map may still be accessed by non-sleepable program or sleepable program. However bpf_map_fd_put_ptr() decreases the ref-counter of the inner map directly through bpf_map_put(), if the ref-counter is the last one (which is true for most cases), the inner map will be freed by ops->map_free() in a kworker. But for now, most .map_free() callbacks don't use synchronize_rcu() or its variants to wait for the elapse of a RCU grace period, so after the invocation of ops->map_free completes, the bpf program which is accessing the inner map may incur use-after-free problem. Fix the free of inner map by invoking bpf_map_free_deferred() after both one RCU grace period and one tasks trace RCU grace period if the inner map has been removed from the outer map before. The deferment is accomplished by using call_rcu() or call_rcu_tasks_trace() when releasing the last ref-counter of bpf map. The newly-added rcu_head field in bpf_map shares the same storage space with work field to reduce the size of bpf_map.

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CVSS v3.1 Score

6.7
MEDIUM
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

Weakness Type (CWE)

CWE-416 Use After Free

Affected Products

Vendor Product
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel

References

Advisories & Patches

https://git.kernel.org/stable/c/37d98fb9c3144c0fddf7f6e99aece9927ac8dce6 https://git.kernel.org/stable/c/62fca83303d608ad4fec3f7428c8685680bb01b0 https://git.kernel.org/stable/c/876673364161da50eed6b472d746ef88242b2368 https://git.kernel.org/stable/c/90c445799fd1dc214d7c6279c144e33a35e29ef2 https://git.kernel.org/stable/c/bfd9b20c4862f41d4590fde11d70a5eeae53dcc5 https://git.kernel.org/stable/c/f91cd728b10c51f6d4a39957ccd56d1e802fc8ee https://git.kernel.org/stable/c/37d98fb9c3144c0fddf7f6e99aece9927ac8dce6 https://git.kernel.org/stable/c/62fca83303d608ad4fec3f7428c8685680bb01b0 https://git.kernel.org/stable/c/876673364161da50eed6b472d746ef88242b2368 https://git.kernel.org/stable/c/90c445799fd1dc214d7c6279c144e33a35e29ef2 https://git.kernel.org/stable/c/bfd9b20c4862f41d4590fde11d70a5eeae53dcc5 https://git.kernel.org/stable/c/f91cd728b10c51f6d4a39957ccd56d1e802fc8ee

Frequently Asked Questions

What is CVE-2023-52447? +
In the Linux kernel, the following vulnerability has been resolved: bpf: Defer the free of inner map when necessary When updating or deleting an inner map in map array or map htab, the map may still be accessed by non-sleepable program or sleepable program. However bpf_map_fd_put_ptr() decreases the ref-counter of the inner map directly through bpf_map_put(), if the ref-counter is the last one (which is true for most cases), the inner map will be freed by ops->map_free() in a kworker. But for now, most .map_free() callbacks don't use synchronize_rcu() or its variants to wait for the elapse of a RCU grace period, so after the invocation of ops->map_free completes, the bpf program which is accessing the inner map may incur use-after-free problem. Fix the free of inner map by invoking bpf_map_free_deferred() after both one RCU grace period and one tasks trace RCU grace period if the inner map has been removed from the outer map before. The deferment is accomplished by using call_rcu() or call_rcu_tasks_trace() when releasing the last ref-counter of bpf map. The newly-added rcu_head field in bpf_map shares the same storage space with work field to reduce the size of bpf_map. It has a CVSS v3.1 base score of 6.7 (MEDIUM).
How severe is CVE-2023-52447? +
CVE-2023-52447 has a CVSS v3.1 score of 6.7 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-2023-52447? +
CVE-2023-52447 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-2023-52447? +
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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