From 02fc32cecf2effea2c0e311ccb5a9bb2a77008b3 Mon Sep 17 00:00:00 2001
From: Min Deng <minotes.net@gmail.com>
Date: Mon, 18 Nov 2024 09:09:28 +0800
Subject: [PATCH] fix(exif): #20 Panic depth shouldn't be greater than 1

---
 src/exif/exif_iter.rs |  2 +-
 src/exif/travel.rs    | 18 ++++++++++++------
 2 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/src/exif/exif_iter.rs b/src/exif/exif_iter.rs
index bf6d968..ff0bdb0 100644
--- a/src/exif/exif_iter.rs
+++ b/src/exif/exif_iter.rs
@@ -379,7 +379,7 @@ impl Iterator for ExifIter {
                     match entry {
                         IfdEntry::IfdNew(new_ifd) => {
                             if new_ifd.offset <= ifd.offset {
-                                tracing::debug!(
+                                tracing::error!(
                                     ?tag_code,
                                     ?new_ifd,
                                     "bad new SUB-IFD: offset is smaller than current IFD"
diff --git a/src/exif/travel.rs b/src/exif/travel.rs
index 70278b4..ee47000 100644
--- a/src/exif/travel.rs
+++ b/src/exif/travel.rs
@@ -141,11 +141,9 @@ impl<'a> IfdHeaderTravel<'a> {
 
     #[tracing::instrument(skip(self))]
     pub fn travel_ifd(&mut self, depth: usize) -> Result<(), ParsingError> {
-        // Currently, we ignore ifd1 data in *.tif files
-        if depth > 1 {
-            let msg = "depth shouldn't be greater than 1";
+        if depth >= 3 {
+            let msg = "depth shouldn't be greater than 3";
             tracing::error!(msg);
-            debug_assert!(false, "{}", msg);
             return Err(ParsingError::Failed(msg.into()));
         }
 
@@ -161,7 +159,15 @@ impl<'a> IfdHeaderTravel<'a> {
             pos += IFD_ENTRY_SIZE;
 
             if let Some(ifd) = sub_ifd {
-                sub_ifds.push(ifd);
+                if ifd.offset <= self.offset {
+                    tracing::error!(
+                        current_ifd_offset = self.offset,
+                        subifd_offset = ifd.offset,
+                        "bad new SUB-IFD in TIFF: offset is smaller than current IFD"
+                    );
+                } else {
+                    sub_ifds.push(ifd);
+                }
             }
         }
 
@@ -169,7 +175,7 @@ impl<'a> IfdHeaderTravel<'a> {
             ifd.travel_ifd(depth + 1)?;
         }
 
-        // ignore ifd1 in TIFF
+        // Currently, we ignore ifd1 data in *.tif files
         Ok(())
     }
 }