CVE-2026-64432

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

fs/ntfs3: validate Dirty Page Table capacity in log_replay copy_lcns

In the analysis pass of $LogFile journal replay, log_replay() copies LCNs from each action log record into an existing Dirty Page Table (DPT) entry without bounding the destination index. A crafted NTFS image with DPT entry lcns_follow=1 and an action log record with lcns_follow=2 produces a kernel slab out-of-bounds write at mount time:

BUG: KASAN: slab-out-of-bounds in log_replay+0x654c/0xdb60 Write of size 8 at addr ffff8880095e1040 by task mount

Two attacker-controlled fields can drive j+i past the allocated page_lcns[] array:

1. dp->lcns_follow (capacity) can be smaller than lrh->lcns_follow.
2. lrh->target_vcn may be smaller than dp->vcn, making the u64 subtraction wrap to a huge size_t.

Validate target VCN delta and per-record LCN count against the DPT entry capacity, bail via the existing out: cleanup label with -EINVAL.

This mirrors the bounds-check pattern added in commit b2bc7c44ed17 (fs/ntfs3: Fix slab-out-of-bounds read in DeleteIndexEntryRoot) and commit 0ca0485e4b2e (fs/ntfs3: validate rec->used in journal-replay file record check).

Weakness

The product writes data past the end, or before the beginning, of the intended buffer.

Affected Software

Potential Mitigations

• Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.

• For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer.

• Be wary that a language’s interface to native code may still be subject to overflows, even if the language itself is theoretically safe.

• Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.

• Examples include the Safe C String Library (SafeStr) by Messier and Viega [REF-57], and the Strsafe.h library from Microsoft [REF-56]. These libraries provide safer versions of overflow-prone string-handling functions.

• Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking.

• D3-SFCV (Stack Frame Canary Validation) from D3FEND [REF-1334] discusses canary-based detection in detail.

• Consider adhering to the following rules when allocating and managing an application’s memory:

• Run or compile the software using features or extensions that randomly arrange the positions of a program’s executable and libraries in memory. Because this makes the addresses unpredictable, it can prevent an attacker from reliably jumping to exploitable code.

• Examples include Address Space Layout Randomization (ASLR) [REF-58] [REF-60] and Position-Independent Executables (PIE) [REF-64]. Imported modules may be similarly realigned if their default memory addresses conflict with other modules, in a process known as “rebasing” (for Windows) and “prelinking” (for Linux) [REF-1332] using randomly generated addresses. ASLR for libraries cannot be used in conjunction with prelink since it would require relocating the libraries at run-time, defeating the whole purpose of prelinking.

• For more information on these techniques see D3-SAOR (Segment Address Offset Randomization) from D3FEND [REF-1335].

• Use a CPU and operating system that offers Data Execution Protection (using hardware NX or XD bits) or the equivalent techniques that simulate this feature in software, such as PaX [REF-60] [REF-61]. These techniques ensure that any instruction executed is exclusively at a memory address that is part of the code segment.

• For more information on these techniques see D3-PSEP (Process Segment Execution Prevention) from D3FEND [REF-1336].

References

• https://git.kernel.org/stable/c/3aa96956ca2200674e2a8f9c23ec6ecd45e5010f
• https://git.kernel.org/stable/c/57382ec6ac63b63dce2789e835fded28b698ae79
• https://git.kernel.org/stable/c/946046841013ebac8492ef49651c53638d7a9a6a
• https://git.kernel.org/stable/c/964c3fae1dfc49dde5468eace940f199cda234e9
• https://git.kernel.org/stable/c/c6f9e804f73ef809529865fbc7256dd189ff8c33
• https://git.kernel.org/stable/c/cf28fc1658463d768657cf1c27a83980d4ba7ef2
• https://git.kernel.org/stable/c/f433acc85b86f327d03ba8b03a33c105c51053de