CVE-2023-52564 Affecting kernel-default-extra package, versions <5.14.21-150500.55.59.1


Severity

Recommended
0.0
medium
0
10

Based on SUSE Linux Enterprise Server security rating.

Threat Intelligence

EPSS
0.05% (18th percentile)

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  • Snyk IDSNYK-SLES155-KERNELDEFAULTEXTRA-6747085
  • published1 May 2024
  • disclosed30 Apr 2024

Introduced: 30 Apr 2024

CVE-2023-52564  (opens in a new tab)

How to fix?

Upgrade SLES:15.5 kernel-default-extra to version 5.14.21-150500.55.59.1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-default-extra package and not the kernel-default-extra package as distributed by SLES. See How to fix? for SLES:15.5 relevant fixed versions and status.

In the Linux kernel, the following vulnerability has been resolved:

Revert "tty: n_gsm: fix UAF in gsm_cleanup_mux"

This reverts commit 9b9c8195f3f0d74a826077fc1c01b9ee74907239.

The commit above is reverted as it did not solve the original issue.

gsm_cleanup_mux() tries to free up the virtual ttys by calling gsm_dlci_release() for each available DLCI. There, dlci_put() is called to decrease the reference counter for the DLCI via tty_port_put() which finally calls gsm_dlci_free(). This already clears the pointer which is being checked in gsm_cleanup_mux() before calling gsm_dlci_release(). Therefore, it is not necessary to clear this pointer in gsm_cleanup_mux() as done in the reverted commit. The commit introduces a null pointer dereference: <TASK> ? __die+0x1f/0x70 ? page_fault_oops+0x156/0x420 ? search_exception_tables+0x37/0x50 ? fixup_exception+0x21/0x310 ? exc_page_fault+0x69/0x150 ? asm_exc_page_fault+0x26/0x30 ? tty_port_put+0x19/0xa0 gsmtty_cleanup+0x29/0x80 [n_gsm] release_one_tty+0x37/0xe0 process_one_work+0x1e6/0x3e0 worker_thread+0x4c/0x3d0 ? __pfx_worker_thread+0x10/0x10 kthread+0xe1/0x110 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x2f/0x50 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1b/0x30 </TASK>

The actual issue is that nothing guards dlci_put() from being called multiple times while the tty driver was triggered but did not yet finished calling gsm_dlci_free().

CVSS Scores

version 3.1