CVE-2025-38711: smb/server: avoid deadlock when linking with ReplaceIfExists

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-09-04 · updated 2026-10-19
Weakness: CWE-667

Description

In the Linux kernel, the following vulnerability has been resolved: smb/server: avoid deadlock when linking with ReplaceIfExists If smb2_create_link() is called with ReplaceIfExists set and the name does exist then a deadlock will happen. ksmbd_vfs_kern_path_locked() will return with success and the parent directory will be locked. ksmbd_vfs_remove_file() will then remove the file. ksmbd_vfs_link() will then be called while the parent is still locked. It will try to lock the same parent and will deadlock. This patch moves the ksmbd_vfs_kern_path_unlock() call to *before* ksmbd_vfs_link() and then simplifies the code, removing the file_present flag variable.

Affected products

Debian Linux: 11.0
Linux kernel: from 5.15 before 5.15.190; from 5.16 before 6.1.149; from 6.2 before 6.6.103; from 6.7 before 6.12.43; from 6.13 before 6.15.11; from 6.16 before 6.16.2 — fixed in 5.15.190, 6.1.149, 6.12.43, 6.15.11, 6.16.2, 6.6.103

How to fix

Upgrade to a fixed version: Linux kernel 5.15.190, 6.1.149, 6.12.43, 6.15.11. Check the vendor advisory for mitigations.

References

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