Bug 2448597 (CVE-2025-71266)

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.