[PATCH] Fix: ext4: add sanity check for inode inline write range

[Ahmet Eray Karadag]

Add a simple check in ext4_try_to_write_inline_data() to prevent
writes that extend past the inode's inline data area. The function
now returns -EINVAL if pos + len exceeds i_inline_size.

This avoids invalid inline write attempts and keeps the write path
consistent with the inode limits.

Reported-by: syzbot+f3185be57d7e8dda32b8@xxxxxxxxxxxxxxxxxxxxxxxxx
Link: https://syzkaller.appspot.com/bug?extid=f3185be57d7e8dda32b8
Co-developed-by: Albin Babu Varghese <albinbabuvarghese20@xxxxxxxxx> 
Signed-off-by: Albin Babu Varghese <albinbabuvarghese20@xxxxxxxxx>
Signed-off-by: Ahmet Eray Karadag <eraykrdg1@xxxxxxxxx>
---
 fs/ext4/inline.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c
index 1b094a4f3866..13ba56e8e334 100644
--- a/fs/ext4/inline.c
+++ b/fs/ext4/inline.c
@@ -782,6 +782,16 @@ int ext4_write_inline_data_end(struct inode *inode, loff_t pos, unsigned len,
 	struct ext4_iloc iloc;
 	int ret = 0, ret2;
 
+	if ((pos + len) > EXT4_I(inode)->i_inline_size) {
+			ext4_warning_inode(inode,
+				"inline write beyond capacity (pos=%lld, len=%u, inline_size=%d)",
+				pos, len, EXT4_I(inode)->i_inline_size);
+		folio_unlock(folio);
+		folio_put(folio);
+		ret = -EINVAL;
+		goto out;
+	}
+
 	if (unlikely(copied < len) && !folio_test_uptodate(folio))
 		copied = 0;
 
@@ -838,8 +848,8 @@ int ext4_write_inline_data_end(struct inode *inode, loff_t pos, unsigned len,
 	 */
 	if (pos + len > inode->i_size && ext4_can_truncate(inode))
 		ext4_orphan_add(handle, inode);
-
-	ret2 = ext4_journal_stop(handle);
+	if (handle)
+		ret2 = ext4_journal_stop(handle);
 	if (!ret)
 		ret = ret2;
 	if (pos + len > inode->i_size) {
-- 
2.43.0