1 files changed, 42 insertions, 3 deletions

diff --git a/fs/ntfs3/index.c b/fs/ntfs3/index.c
index 5344b29b0577..ade276225999 100644
--- a/fs/ntfs3/index.c
+++ b/fs/ntfs3/index.c
@@ -1742,6 +1742,22 @@ static int indx_insert_into_root(struct ntfs_index *indx, struct ntfs_inode *ni,
 	hdr_used = le32_to_cpu(hdr->used);
 	hdr_total = le32_to_cpu(hdr->total);
 
+	/*
+	 * The destination INDEX_BUFFER has 'hdr_total' bytes of payload
+	 * available after the header, of which 'hdr_used' are already
+	 * consumed by the single terminal END entry installed by
+	 * indx_new(). A crafted image can present a resident root whose
+	 * non-last entries (summing to 'to_move') exceed what fits in
+	 * this buffer; copying them unchecked would overrun the
+	 * kmalloc(1u << indx->index_bits) allocation backing the new
+	 * buffer. Reject the copy in that case.
+	 */
+	if (to_move > hdr_total - hdr_used) {
+		err = -EINVAL;
+		ntfs_set_state(sbi, NTFS_DIRTY_ERROR);
+		goto out_put_n;
+	}
+
 	/* Copy root entries into new buffer. */
 	hdr_insert_head(hdr, re, to_move);
 
@@ -1846,6 +1862,20 @@ indx_insert_into_buffer(struct ntfs_index *indx, struct ntfs_inode *ni,
 	memcpy(up_e, sp, sp_size);
 
 	used1 = le32_to_cpu(hdr1->used);
+
+	/*
+	 * hdr_find_split does not validate per-entry sizes, so a crafted
+	 * NTFS_DE whose le16 size field is out of range can place sp such
+	 * that (PtrOffset(hdr1, sp) + sp_size) exceeds used1. Without this
+	 * guard the u32 'used = used1 - to_copy - sp_size' underflows and
+	 * the subsequent memmove count becomes a near-4-GiB value,
+	 * triggering an out-of-bounds kernel write.
+	 */
+	if (PtrOffset(hdr1, sp) + sp_size > used1) {
+		err = -EINVAL;
+		goto out;
+	}
+
 	hdr1_saved = kmemdup(hdr1, used1, GFP_NOFS);
 	if (!hdr1_saved) {
 		err = -ENOMEM;
@@ -2022,13 +2052,21 @@ out1:
 static struct indx_node *indx_find_buffer(struct ntfs_index *indx,
 					  struct ntfs_inode *ni,
 					  const struct INDEX_ROOT *root,
-					  __le64 vbn, struct indx_node *n)
+					  __le64 vbn, struct indx_node *n,
+					  int depth)
 {
 	int err;
 	const struct NTFS_DE *e;
 	struct indx_node *r;
 	const struct INDEX_HDR *hdr = n ? &n->index->ihdr : &root->ihdr;
 
+	/*
+	 * Limit recursion depth to prevent stack overflow from crafted
+	 * images.  Use the same bound as the fnd->nodes array (20).
+	 */
+	if (depth > ARRAY_SIZE(((struct ntfs_fnd *)NULL)->nodes))
+		return ERR_PTR(-EINVAL);
+
 	/* Step 1: Scan one level. */
 	for (e = hdr_first_de(hdr);; e = hdr_next_de(hdr, e)) {
 		if (!e)
@@ -2049,7 +2087,8 @@ static struct indx_node *indx_find_buffer(struct ntfs_index *indx,
 			if (err)
 				return ERR_PTR(err);
 
-			r = indx_find_buffer(indx, ni, root, vbn, n);
+			r = indx_find_buffer(indx, ni, root, vbn, n,
+					     depth + 1);
 			if (r)
 				return r;
 		}
@@ -2462,7 +2501,7 @@ int indx_delete_entry(struct ntfs_index *indx, struct ntfs_inode *ni,
 
 		fnd_clear(fnd);
 
-		in = indx_find_buffer(indx, ni, root, sub_vbn, NULL);
+		in = indx_find_buffer(indx, ni, root, sub_vbn, NULL, 0);
 		if (IS_ERR(in)) {
 			err = PTR_ERR(in);
 			goto out;