From c304a3cc136d69952fe0f50bfaaf04f9762171c8 Mon Sep 17 00:00:00 2001
From: Maria Pospelova <mariapospelova@google.com>
Date: Tue, 3 Mar 2026 10:50:27 +0000
Subject: [PATCH 1/2] Upgrade Group4Reader dimensions from u16 to u32

---
 src/decoder/stream.rs   |   6 +++---
 tests/decode_images.rs  |  21 +++++++++++++++++++++
 tests/images/big_g4.tif | Bin 0 -> 8338 bytes
 3 files changed, 24 insertions(+), 3 deletions(-)
 create mode 100644 tests/images/big_g4.tif

diff --git a/src/decoder/stream.rs b/src/decoder/stream.rs
index e12ac4e..cf67d5d 100644
--- a/src/decoder/stream.rs
+++ b/src/decoder/stream.rs
@@ -260,9 +260,9 @@ impl<R: Read> Read for PackBitsReader<R> {
 pub struct Group4Reader<R: Read> {
     decoder: fax34::decoder::Group4Decoder<io::Bytes<io::BufReader<io::Take<R>>>>,
     line_buf: io::Cursor<Vec<u8>>,
-    height: u16,
+    height: u32,
     width: u16,
-    y: u16,
+    y: u32,
 }
 
 #[cfg(feature = "fax")]
@@ -273,7 +273,7 @@ impl<R: Read> Group4Reader<R> {
         compressed_length: u64,
     ) -> crate::TiffResult<Self> {
         let width = u16::try_from(dimensions.0)?;
-        let height = u16::try_from(dimensions.1)?;
+        let height = dimensions.1;
 
         Ok(Self {
             decoder: fax34::decoder::Group4Decoder::new(
diff --git a/tests/decode_images.rs b/tests/decode_images.rs
index 5448686..84979d8 100644
--- a/tests/decode_images.rs
+++ b/tests/decode_images.rs
@@ -720,3 +720,24 @@ fn extra_bits_gray() {
 fn extra_bits_rgb() {
     test_image_sum_u8("extra_bits_rgb_8b.tiff", ColorType::RGB(8), 0);
 }
+
+
+#[test]
+#[cfg(feature = "fax")]
+fn test_decode_huge_g4() {
+    let path = PathBuf::from(TEST_IMAGE_DIR).join("big_g4.tif");
+    let img_file = File::open(path).expect("failed to open large G4 test image");
+    let mut decoder = tiff::decoder::Decoder::new(img_file).expect("failed to create decoder");
+
+    let (width, height) = decoder.dimensions().expect("failed to get dimensions");
+    
+    assert!(height > u16::MAX as u32, "Test image height {} is not large enough to test u16 overflow", height);
+
+    let result = decoder.read_image().expect("failed to decode huge G4 image");
+
+    if let tiff::decoder::DecodingResult::U8(data) = result {
+        assert_eq!(data.len(), (width as usize * height as usize));
+    } else {
+        panic!("Unexpected decoding result type");
+    }
+}
\ No newline at end of file
diff --git a/tests/images/big_g4.tif b/tests/images/big_g4.tif
new file mode 100644
index 0000000000000000000000000000000000000000..2b3e7386aa50be5457dcf9861997bd75731a0b6f
GIT binary patch
literal 8338
zcmeIuF$#b%5Jb^gBcj-7qm6~NH}O_t>7{i7DRKqj2SS!%vc)^kL(?w390U+R009IL
zKmY**5I_I{1Q0*~0R#|0009ILKmY**5I_I{1Q7VWfTp;5T^giF3i-)5+A@clDo<r@
h-RY`)cE54<?9x*H=1ptKZ|7UpcU8$*-qZVzo<F{9<|+UH

literal 0
HcmV?d00001


From a0a95ef86e481dc925cb2599ba392f883e2c0193 Mon Sep 17 00:00:00 2001
From: Maria Pospelova <mariapospelova@google.com>
Date: Tue, 3 Mar 2026 13:26:09 +0000
Subject: [PATCH 2/2] Fix formatting

---
 tests/decode_images.rs | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/tests/decode_images.rs b/tests/decode_images.rs
index 84979d8..74f9f9f 100644
--- a/tests/decode_images.rs
+++ b/tests/decode_images.rs
@@ -721,7 +721,6 @@ fn extra_bits_rgb() {
     test_image_sum_u8("extra_bits_rgb_8b.tiff", ColorType::RGB(8), 0);
 }
 
-
 #[test]
 #[cfg(feature = "fax")]
 fn test_decode_huge_g4() {
@@ -730,14 +729,20 @@ fn test_decode_huge_g4() {
     let mut decoder = tiff::decoder::Decoder::new(img_file).expect("failed to create decoder");
 
     let (width, height) = decoder.dimensions().expect("failed to get dimensions");
-    
-    assert!(height > u16::MAX as u32, "Test image height {} is not large enough to test u16 overflow", height);
 
-    let result = decoder.read_image().expect("failed to decode huge G4 image");
+    assert!(
+        height > u16::MAX as u32,
+        "Test image height {} is not large enough to test u16 overflow",
+        height
+    );
+
+    let result = decoder
+        .read_image()
+        .expect("failed to decode huge G4 image");
 
     if let tiff::decoder::DecodingResult::U8(data) = result {
         assert_eq!(data.len(), (width as usize * height as usize));
     } else {
         panic!("Unexpected decoding result type");
     }
-}
\ No newline at end of file
+}