From: Michael Bommarito Date: Tue, 19 May 2026 09:51:35 +0000 (-0400) Subject: fs/ntfs3: bound NTFS_DE view.data_off in UpdateRecordData{Root,Allocation} X-Git-Url: http://git.ipfire.org/gitweb/?a=commitdiff_plain;h=3e127829e57f5190f612412ece4541cb96d5ec7a;p=thirdparty%2Fkernel%2Flinux.git fs/ntfs3: bound NTFS_DE view.data_off in UpdateRecordData{Root,Allocation} In do_action()'s UpdateRecordDataRoot (fslog.c:3489) and UpdateRecordDataAllocation (fslog.c:3697) cases, the memmove destination is `Add2Ptr(e, le16_to_cpu(e->view.data_off))`, where e->view.data_off comes from an on-disk NTFS_DE inside an INDEX_ROOT or INDEX_BUFFER. Neither case validates view.data_off + dlen against e->size; the existing check_if_index_root / check_if_alloc_index helpers walk the entry chain and validate the entry's offset, but not its internal view fields. The neighbouring read sites (e.g., fs/ntfs3/index.c when iterating view entries) check view.data_off + view.data_size <= e->size. Apply the same bound at the two memmove sites. Reproduced under UML+KASAN on mainline 8d90b09e6741 via pr_warn-only probe instrumentation: with view.data_off forced to 0xFFFC, the memmove writes 32 bytes past the end of the NTFS_DE. This is similar in shape to Pavitra Jha's 2026-05-02 patch "fs/ntfs3: prevent oob in case UpdateRecordDataRoot" (<20260502105008.21827-1-jhapavitra98@gmail.com>) which proposes calling ntfs3_bad_de_range(); that helper does not exist in mainline. This patch uses inline checks. Fixes: b46acd6a6a62 ("fs/ntfs3: Add NTFS journal") Cc: stable@vger.kernel.org Reported-by: Pavitra Jha Closes: https://lore.kernel.org/ntfs3/20260502105008.21827-1-jhapavitra98@gmail.com/ Assisted-by: Claude:claude-opus-4-7 Signed-off-by: Michael Bommarito Signed-off-by: Konstantin Komarov --- diff --git a/fs/ntfs3/fslog.c b/fs/ntfs3/fslog.c index 95e1cdb47475b..e1f1c6a267851 100644 --- a/fs/ntfs3/fslog.c +++ b/fs/ntfs3/fslog.c @@ -3525,6 +3525,18 @@ move_data: e = Add2Ptr(attr, le16_to_cpu(lrh->attr_off)); + /* + * e->view.data_off and dlen come from the on-disk + * INDEX_ROOT entry / LRH. The neighbouring read sites + * (e.g. fs/ntfs3/index.c) check that + * view.data_off + view.data_size <= e->size; mirror that + * bound here so the memmove cannot reach past the entry. + */ + if (le16_to_cpu(e->view.data_off) > le16_to_cpu(e->size) || + le16_to_cpu(e->view.data_off) + dlen > + le16_to_cpu(e->size)) + goto dirty_vol; + memmove(Add2Ptr(e, le16_to_cpu(e->view.data_off)), data, dlen); mi->dirty = true; @@ -3731,6 +3743,12 @@ move_data: goto dirty_vol; } + /* See UpdateRecordDataRoot for the rationale. */ + if (le16_to_cpu(e->view.data_off) > le16_to_cpu(e->size) || + le16_to_cpu(e->view.data_off) + dlen > + le16_to_cpu(e->size)) + goto dirty_vol; + memmove(Add2Ptr(e, le16_to_cpu(e->view.data_off)), data, dlen); a_dirty = true;