In log_replay()'s analysis pass, after find_dp() returns a valid DIR_PAGE_ENTRY for the (target_attr, target_vcn) tuple, the copy_lcns block walks lrh->lcns_follow further entries: t16 = le16_to_cpu(lrh->lcns_follow); for (i = 0; i < t16; i++) { size_t j = (size_t)(le64_to_cpu(lrh->target_vcn) - le64_to_cpu(dp->vcn)); dp->page_lcns[j + i] = lrh->page_lcns[i]; } find_dp() only validates that target_vcn falls within [dp->vcn, dp->vcn + dp->lcns_follow), i.e., that the FIRST cluster is covered. The walk through the further entries is not bounded against dp->lcns_follow. For a malformed LRH where target_vcn = dp->vcn + dp->lcns_follow - 1 and lrh->lcns_follow > 1, the i > 0 writes overflow the dp's allocated page_lcns[] array. Add the missing j + lrh->lcns_follow <= dp->lcns_follow guard. Reproduced under UML+KASAN on mainline 8d90b09e6741 as a slab-out-of-bounds write of size 8 from log_replay+0x68d4 on the mount path. This is distinct from Pavitra Jha's 2026-05-02 patch ("fs/ntfs3: validate lcns_follow in log_replay conversion", <20260502154252.164586-1-jhapavitra98@gmail.com>) which addresses the separate version-0 dirty-page-table conversion path's memmove(&dp->vcn, ...) call. The two fixes are complementary; both should land. Fixes: b46acd6a6a62 ("fs/ntfs3: Add NTFS journal") Cc: stable@vger.kernel.org Assisted-by: Claude:claude-opus-4-7 Signed-off-by: Michael Bommarito --- fs/ntfs3/fslog.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/fs/ntfs3/fslog.c b/fs/ntfs3/fslog.c index acfa18b84401e..f409611f2530d 100644 --- a/fs/ntfs3/fslog.c +++ b/fs/ntfs3/fslog.c @@ -4547,6 +4547,19 @@ int log_replay(struct ntfs_inode *ni, bool *initialized) * whole routine a loop, case Lcns do not fit below. */ t16 = le16_to_cpu(lrh->lcns_follow); + /* + * find_dp() only validates that target_vcn is the first + * cluster covered by dp. The walk through lrh->lcns_follow + * further entries must stay within the allocated + * dp->page_lcns[] array, which is sized by dp->lcns_follow. + */ + if (le64_to_cpu(lrh->target_vcn) - le64_to_cpu(dp->vcn) + t16 > + le32_to_cpu(dp->lcns_follow)) { + err = -EINVAL; + log->set_dirty = true; + goto out; + } + for (i = 0; i < t16; i++) { size_t j = (size_t)(le64_to_cpu(lrh->target_vcn) - le64_to_cpu(dp->vcn)); -- 2.53.0