[PATCH 12/18] fs/ntfs3: Add a check for attr_names and oatbl

[Konstantin Komarov]

Added out-of-bound checking for *ane (ATTR_NAME_ENTRY).

Reported-by: lei lu <llfamsec@xxxxxxxxx>
Fixes: 865e7a7700d93 ("fs/ntfs3: Reduce stack usage")
Signed-off-by: Konstantin Komarov <almaz.alexandrovich@xxxxxxxxxxxxxxxxxxxx>
---
 fs/ntfs3/fslog.c | 38 ++++++++++++++++++++++++++++++++------
 1 file changed, 32 insertions(+), 6 deletions(-)

diff --git a/fs/ntfs3/fslog.c b/fs/ntfs3/fslog.c
index d7807d255dfe..055c2af602c3 100644
--- a/fs/ntfs3/fslog.c
+++ b/fs/ntfs3/fslog.c
@@ -3722,6 +3722,8 @@ int log_replay(struct ntfs_inode *ni, bool *initialized)
 
 	u64 rec_lsn, checkpt_lsn = 0, rlsn = 0;
 	struct ATTR_NAME_ENTRY *attr_names = NULL;
+	u32 attr_names_bytes = 0;
+	u32 oatbl_bytes = 0;
 	struct RESTART_TABLE *dptbl = NULL;
 	struct RESTART_TABLE *trtbl = NULL;
 	const struct RESTART_TABLE *rt;
@@ -3736,6 +3738,7 @@ int log_replay(struct ntfs_inode *ni, bool *initialized)
 	struct NTFS_RESTART *rst = NULL;
 	struct lcb *lcb = NULL;
 	struct OPEN_ATTR_ENRTY *oe;
+	struct ATTR_NAME_ENTRY *ane;
 	struct TRANSACTION_ENTRY *tr;
 	struct DIR_PAGE_ENTRY *dp;
 	u32 i, bytes_per_attr_entry;
@@ -4314,17 +4317,40 @@ int log_replay(struct ntfs_inode *ni, bool *initialized)
 	lcb = NULL;
 
 check_attribute_names2:
-	if (rst->attr_names_len && oatbl) {
-		struct ATTR_NAME_ENTRY *ane = attr_names;
-		while (ane->off) {
+	if (attr_names && oatbl) {
+		off = 0;
+		for (;;) {
+			/* Check we can use attribute name entry 'ane'. */
+			static_assert(sizeof(*ane) == 4);
+			if (off + sizeof(*ane) > attr_names_bytes) {
+				/* just ignore the rest. */
+				break;
+			}
+
+			ane = Add2Ptr(attr_names, off);
+			t16 = le16_to_cpu(ane->off);
+			if (!t16) {
+				/* this is the only valid exit. */
+				break;
+			}
+
+			/* Check we can use open attribute entry 'oe'. */
+			if (t16 + sizeof(*oe) > oatbl_bytes) {
+				/* just ignore the rest. */
+				break;
+			}
+
 			/* TODO: Clear table on exit! */
-			oe = Add2Ptr(oatbl, le16_to_cpu(ane->off));
+			oe = Add2Ptr(oatbl, t16);
 			t16 = le16_to_cpu(ane->name_bytes);
+			off += t16 + sizeof(*ane);
+			if (off > attr_names_bytes) {
+				/* just ignore the rest. */
+				break;
+			}
 			oe->name_len = t16 / sizeof(short);
 			oe->ptr = ane->name;
 			oe->is_attr_name = 2;
-			ane = Add2Ptr(ane,
-				      sizeof(struct ATTR_NAME_ENTRY) + t16);
 		}
 	}
 
-- 
2.34.1