CVE-2025-71266 — fs: ntfs3: check return value of indx_find to avoid infinite loop

Affected: Linux, Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP, Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP, Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP

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

fs: ntfs3: check return value of indx_find to avoid infinite loop

We found an infinite loop bug in the ntfs3 file system that can lead to a Denial-of-Service (DoS) condition.

A malformed dentry in the ntfs3 filesystem can cause the kernel to hang during the lookup operations. By setting the HAS_SUB_NODE flag in an INDEX_ENTRY within a directory's INDEX_ALLOCATION block and manipulating the VCN pointer, an attacker can cause the indx_find() function to repeatedly read the same block, allocating 4 KB of memory each time. The kernel lacks VCN loop detection and depth limits, causing memory exhaustion and an OOM crash.

This patch adds a return value check for fnd_push() to prevent a memory exhaustion vulnerability caused by infinite loops. When the index exceeds the size of the fnd->nodes array, fnd_push() returns -EINVAL. The indx_find() function checks this return value and stops processing, preventing further memory allocation.

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CVE-2025-71266 — fs: ntfs3: check return value of indx_find to avoid infinite loop