CVE-2023-53608: linux kernel Use-After-Free — Fix

Description

In the Linux kernel, the following vulnerability has been resolved: nilfs2: fix potential UAF of struct nilfs_sc_info in nilfs_segctor_thread() The finalization of nilfs_segctor_thread() can race with nilfs_segctor_kill_thread() which terminates that thread, potentially causing a use-after-free BUG as KASAN detected. At the end of nilfs_segctor_thread(), it assigns NULL to "sc_task" member of "struct nilfs_sc_info" to indicate the thread has finished, and then notifies nilfs_segctor_kill_thread() of this using waitqueue "sc_wait_task" on the struct nilfs_sc_info. However, here, immediately after the NULL assignment to "sc_task", it is possible that nilfs_segctor_kill_thread() will detect it and return to continue the deallocation, freeing the nilfs_sc_info structure before the thread does the notification. This fixes the issue by protecting the NULL assignment to "sc_task" and its notification, with spinlock "sc_state_lock" of the struct nilfs_sc_info. Since nilfs_segctor_kill_thread() does a final check to see if "sc_task" is NULL with "sc_state_lock" locked, this can eliminate the race.

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CVSS v3.1 Score

7.8

HIGH

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

Weakness Type (CWE)

CWE-416 Use After Free

Affected Products

Vendor	Product	Versions
linux	linux_kernel	2.6.30 — 4.14.313
linux	linux_kernel	4.15 — 4.19.281
linux	linux_kernel	4.20 — 5.4.241
linux	linux_kernel	5.5 — 5.10.178
linux	linux_kernel	5.11 — 5.15.107
linux	linux_kernel	5.16 — 6.1.24
linux	linux_kernel	6.2 — 6.2.11
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All

References

Advisories & Patches

https://git.kernel.org/stable/c/034cce77d52ba013ce62b4f5258c29907eb1ada5 https://git.kernel.org/stable/c/0dbf0e64b91ee8fcb278aea93eb06fc7d56ecbcc https://git.kernel.org/stable/c/613bf23c070d11c525268f2945aa594704a9b764 https://git.kernel.org/stable/c/6be49d100c22ffea3287a4b19d7639d259888e33 https://git.kernel.org/stable/c/92684e02654c91a61a0b0561433b710bcece19fe https://git.kernel.org/stable/c/b4d80bd6370b81a1725b6b8f7894802c23a14e9f https://git.kernel.org/stable/c/bae009a2f1b7c2011d2e92d8c84868d315c0b97e https://git.kernel.org/stable/c/f32297dba338dc06d62286dedb3cdbd5175b1719

Frequently Asked Questions

What is CVE-2023-53608? +

In the Linux kernel, the following vulnerability has been resolved: nilfs2: fix potential UAF of struct nilfs_sc_info in nilfs_segctor_thread() The finalization of nilfs_segctor_thread() can race with nilfs_segctor_kill_thread() which terminates that thread, potentially causing a use-after-free BUG as KASAN detected. At the end of nilfs_segctor_thread(), it assigns NULL to "sc_task" member of "struct nilfs_sc_info" to indicate the thread has finished, and then notifies nilfs_segctor_kill_thread() of this using waitqueue "sc_wait_task" on the struct nilfs_sc_info. However, here, immediately after the NULL assignment to "sc_task", it is possible that nilfs_segctor_kill_thread() will detect it and return to continue the deallocation, freeing the nilfs_sc_info structure before the thread does the notification. This fixes the issue by protecting the NULL assignment to "sc_task" and its notification, with spinlock "sc_state_lock" of the struct nilfs_sc_info. Since nilfs_segctor_kill_thread() does a final check to see if "sc_task" is NULL with "sc_state_lock" locked, this can eliminate the race. It has a CVSS v3.1 base score of 7.8 (HIGH).

How severe is CVE-2023-53608? +

CVE-2023-53608 has a CVSS v3.1 score of 7.8 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching.

What products are affected by CVE-2023-53608? +

CVE-2023-53608 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-2023-53608? +

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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