CVE-2026-89616fs/ntfs3: fix info-leak on partial LZNT decompress in ni_read_frame()

Official description

In the Linux kernel, the following vulnerability has been resolved: fs/ntfs3: fix info-leak on partial LZNT decompress in ni_read_frame() ni_read_frame() decompresses an LZNT $DATA frame into the vmapped target pages and then trusts decompress_lznt()'s return value: unc_size = decompress_lznt(frame_ondisk, ondisk_size, frame_mem, frame_size); if ((ssize_t)unc_size < 0) err = unc_size; else if (!unc_size || unc_size > frame_size) err = -EINVAL; decompress_lznt() stops as soon as the compressed stream is exhausted (e.g. a zero chunk header) and returns the number of bytes it actually wrote, which may be far less than frame_size. The bytes between unc_size and frame_size are never written. The only memset() that follows zeroes the region beyond i_valid; when the frame lies entirely within the file's valid size that memset() does not run, so the gap retains whatever was in the just-vmapped pages. All pages are then marked uptodate and returned to userspace, disclosing uninitialized (recently-freed) kernel page memory. A crafted compressed file whose stream decompresses to only a few bytes leaks the remainder of every frame on a plain read(2), which is enough to recover kernel pointers and defeat KASLR. Zero the [unc_size, frame_size) tail immediately after a successful LZNT decompress so the remainder reads back as zero.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/7d60a4c49af4d5cb88aa7cbf998d0408bd415055
• https://git.kernel.org/stable/c/cd40eee4923d104ebec9ac7513b971bc441e431d
• https://git.kernel.org/stable/c/77d8efd04745cda23858546afdbd9d07b591758e
• https://git.kernel.org/stable/c/0f699ddb290a24b37e1bc9bf1e3c9dbccf564bea
• https://git.kernel.org/stable/c/376ee45659a4b943df672ad275c63da00655f929
• https://git.kernel.org/stable/c/4a1b39b2e10eb8de86265e80cf2be4396bc1dce4
• https://git.kernel.org/stable/c/35d1ea92c7d946e2ebdbe36cdb2c969c8704bebd