From f2cbe793e2ad185aac3e8399026d7bccc70487cd Mon Sep 17 00:00:00 2001
From: Vitaliy Filippov <vitalif@yourcmc.ru>
Date: Sun, 9 Nov 2025 15:47:54 +0300
Subject: [PATCH] Fix intent_write_allowed check, add offset & len validation
 on start

---
 src/blockstore/blockstore_heap.cpp  | 20 ++++++++++++++++++++
 src/blockstore/blockstore_write.cpp | 20 +++++++++-----------
 2 files changed, 29 insertions(+), 11 deletions(-)

diff --git a/src/blockstore/blockstore_heap.cpp b/src/blockstore/blockstore_heap.cpp
index cf51290e..6a3ea764 100644
--- a/src/blockstore/blockstore_heap.cpp
+++ b/src/blockstore/blockstore_heap.cpp
@@ -354,6 +354,26 @@ corrupted_object:
                     block_num, block_offset, expected_crc32c, wr->crc32c);
                 goto corrupted_object;
             }
+            // Verify offset & len
+            if ((wr->type() == BS_HEAP_SMALL_WRITE || wr->type() == BS_HEAP_INTENT_WRITE) &&
+                (wr->small().offset+wr->small().len > dsk->data_block_size ||
+                wr->small().offset % dsk->bitmap_granularity ||
+                wr->small().len % dsk->bitmap_granularity))
+            {
+                fprintf(stderr, "Error: %s entry %jx:%jx v%ju has invalid offset/length: %u/%u. Metadata is incompatible with current parameters, aborting\n",
+                    wr->type() == BS_HEAP_SMALL_WRITE ? "small_write" : "intent_write",
+                    wr->inode, wr->stripe, wr->version, wr->small().offset, wr->small().len);
+                goto corrupted_object;
+            }
+            if (wr->type() == BS_HEAP_BIG_INTENT &&
+                (wr->big_intent().offset+wr->big_intent().len > dsk->data_block_size ||
+                wr->big_intent().offset % dsk->bitmap_granularity ||
+                wr->big_intent().len % dsk->bitmap_granularity))
+            {
+                fprintf(stderr, "Error: big_intent entry %jx:%jx v%ju has invalid offset/length: %u/%u. Metadata is incompatible with current parameters, aborting\n",
+                    wr->inode, wr->stripe, wr->version, wr->big_intent().offset, wr->big_intent().len);
+                goto corrupted_object;
+            }
             handle_write(block_num, wr);
             block_offset += wr->size;
         }
diff --git a/src/blockstore/blockstore_write.cpp b/src/blockstore/blockstore_write.cpp
index 5cd6a119..d156efca 100644
--- a/src/blockstore/blockstore_write.cpp
+++ b/src/blockstore/blockstore_write.cpp
@@ -72,11 +72,12 @@ bool blockstore_impl_t::intent_write_allowed(blockstore_op_t *op, heap_entry_t *
     {
         return false;
     }
-    bool ok = true, has_intent = false;
+    bool ok = true;
     heap->iterate_with_stable(obj, obj->lsn, [&](heap_entry_t *wr, bool stable)
     {
         // Intent writes are not allowed over buffered writes
-        if (wr->type() == BS_HEAP_SMALL_WRITE)
+        auto t = wr->type();
+        if (t == BS_HEAP_SMALL_WRITE)
         {
             ok = false;
             return false;
@@ -87,17 +88,14 @@ bool blockstore_impl_t::intent_write_allowed(blockstore_op_t *op, heap_entry_t *
             ok = false;
             return false;
         }
-        // One intent-write is allowed even with fsyncs because BIG_WRITE is always counted as fsynced
-        if (dsk.disable_data_fsync && wr->type() == BS_HEAP_INTENT_WRITE)
+        // Intent writes are not allowed over unfinished intent writes
+        if ((t == BS_HEAP_INTENT_WRITE || t == BS_HEAP_BIG_INTENT) && wr->lsn > heap->get_fsynced_lsn())
         {
-            if (has_intent)
-            {
-                ok = false;
-                return false;
-            }
-            has_intent = true;
+            ok = false;
+            return false;
         }
-        if (wr->type() == BS_HEAP_BIG_WRITE || wr->type() == BS_HEAP_BIG_INTENT)
+        // Intent writes are allowed over BIG_WRITEs even with fsyncs because BIG_WRITE is always counted as fsynced
+        if (t == BS_HEAP_BIG_WRITE || t == BS_HEAP_BIG_INTENT)
         {
             return false;
         }