1 files changed, 5 insertions, 1 deletions
diff --git a/ext/fts5/fts5_index.c b/ext/fts5/fts5_index.c
index 7b9d21e87..347ee5690 100644
--- a/ext/fts5/fts5_index.c
+++ b/ext/fts5/fts5_index.c
@@ -4655,9 +4655,13 @@ static void fts5SecureDeleteOverflow(
         int i1 = pLeaf->szLeaf;
         int i2 = 0;
 
+        i1 += fts5GetVarint32(&aPg[i1], iFirst);
+        if( iFirst<iNext ){
+          p->rc = FTS5_CORRUPT;
+          break;
+        }
         aIdx = sqlite3Fts5MallocZero(&p->rc, (pLeaf->nn-pLeaf->szLeaf)+2);
         if( aIdx==0 ) break;
-        i1 += fts5GetVarint32(&aPg[i1], iFirst);
         i2 = sqlite3Fts5PutVarint(aIdx, iFirst-nShift);
         if( i1<pLeaf->nn ){
           memcpy(&aIdx[i2], &aPg[i1], pLeaf->nn-i1);