Fix runtime BOSD

Chunk size and tag is check before handle.
Check if heuristics search is not correct, and the try_ptr goes of the bound,
making dereference an invalid address.

src/bin/eprocess_scan.rs

@@ -29,33 +29,45 @@ fn main() -> Result<(), Box<dyn Error>> {
     // let eprocess_scan_head = driver.scan_active_head(ntosbase)?;
     // let mut eprocess_list: Vec<EprocessPoolChunk> = Vec::new();
     driver.scan_pool(b"Proc", |pool_addr, header, data_addr| {
+        let chunk_size = (header[2] as u64) * 16u64;
+
+        let eprocess_size = driver.pdb_store.get_offset_r("_EPROCESS.struct_size")?;
         let eprocess_name_offset = driver.pdb_store.get_offset_r("_EPROCESS.ImageFileName")?;
         let eprocess_create_time_offset = driver.pdb_store.get_offset_r("_EPROCESS.CreateTime")?;
         let eprocess_exit_time_offset = driver.pdb_store.get_offset_r("_EPROCESS.ExitTime")?;
-        let eprocess_size = driver.pdb_store.get_offset_r("_EPROCESS.struct_size")?;
 
-        let chunk_size = (header[2] as u64) * 16u64;
         let eprocess_valid_start = data_addr;
-        let eprocess_valid_end = pool_addr + chunk_size - eprocess_size;
+        let eprocess_valid_end = (pool_addr + chunk_size) - eprocess_size;
         let mut try_eprocess_ptr = eprocess_valid_start;
 
         let mut create_time = 0u64;
         let mut exit_time = 0u64;
         while try_eprocess_ptr <= eprocess_valid_end {
             driver.deref_addr(try_eprocess_ptr + eprocess_create_time_offset, &mut create_time);
-            driver.deref_addr(try_eprocess_ptr + eprocess_exit_time_offset, &mut exit_time);
+            // driver.deref_addr(try_eprocess_ptr + eprocess_exit_time_offset, &mut exit_time);
             // using heuristics to eliminate false positive
             if driver.windows_ffi.valid_process_time(create_time) {
                 break;
             }
             try_eprocess_ptr += 0x4;        // search exhaustively
         }
+        if (try_eprocess_ptr > eprocess_valid_end) {
+            return Ok(false);
+        }
+
         let mut image_name = [0u8; 15];
         driver.deref_addr(try_eprocess_ptr + eprocess_name_offset, &mut image_name);
-        let eprocess_name = from_utf8(&image_name)?
-                            .to_string()
-                            .trim_end_matches(char::from(0))
-                            .to_string();
+        if let Ok(name) = from_utf8(&image_name) {
+            let eprocess_name = name
+                                .to_string()
+                                .trim_end_matches(char::from(0))
+                                .to_string();
+            println!("pool: 0x{:x} | eprocess: 0x{:x} | {}", pool_addr, try_eprocess_ptr, eprocess_name);
+        }
+        else {
+            println!("pool: 0x{:x} | eprocess: 0x{:x} | {:?}", pool_addr, try_eprocess_ptr, image_name);
+        }
+        Ok(true)
         // eprocess_list.push(EprocessPoolChunk {
         //     pool_addr,
         //     eprocess_addr: try_eprocess_ptr,
@@ -63,8 +75,6 @@ fn main() -> Result<(), Box<dyn Error>> {
         //     create_time: to_epoch(create_time),
         //     exit_time: to_epoch(exit_time)
         // });
-        println!("pool: {} | eprocess: {}: {}", pool_addr, try_eprocess_ptr, eprocess_name);
-        Ok(try_eprocess_ptr <= eprocess_valid_end)
     })?;
 
     println!("NtUnloadDriver() -> 0x{:x}", driver.shutdown());

src/driver_state.rs

@@ -163,23 +163,47 @@ impl DriverState {
             if ptr >= end_address {
                 break;
             }
+
             let pool_addr = ptr;
             let mut header = vec![0u8; pool_header_size as usize];
             self.deref_addr_ptr(pool_addr, header.as_mut_ptr(), pool_header_size);
+            let chunk_size = (header[2] as u64) * 16u64;
 
-            let success = handler(ptr, &header, pool_addr + pool_header_size)?;
-            if success {
-                let chunk_size = (header[2] as u64) * 16u64;
-                ptr += chunk_size /* pass this chunk */
+            if pool_addr + chunk_size > end_address {
+                // the chunk found is not a valid chunk for sure
+                break;
+            }
+
+            // TODO: move to another function, with tables mapping fromm tag -> struct
+            // automatically reject bad chunk
+            // Proc -> _EPROCESS
+            // Thre -> _KTHREAD
+            if tag == b"Proc" {
+                let eprocess_size = self.pdb_store.get_offset_r("_EPROCESS.struct_size")?;
+                let minimum_data_size = eprocess_size + pool_header_size;
+                if chunk_size < minimum_data_size {
+                    ptr += 0x4;
+                    continue;
+                }
             }
             else {
-                ptr += 0x4 /* search next */
-            };
+                println!("Tag unknown");
+                break;
+            }
+
+            let success = handler(pool_addr, &header, pool_addr + pool_header_size)?;
+            if success {
+                ptr += chunk_size; /* pass this chunk */
+            }
+            else {
+                ptr += 0x4; /* search next */
+            }
         }
         Ok(true)
     }
 
     pub fn deref_addr<T>(&self, addr: u64, outbuf: &mut T) {
+        // println!("deref addr: 0x{:x}", addr);
         let code = DriverAction::DereferenceAddress.get_code();
         let size: usize = size_of_val(outbuf);
         let mut input = InputData {

src/pdb_store.rs

@@ -99,7 +99,10 @@ impl PdbStore {
         ];
 
         let mut need_structs = HashMap::new();
-        need_structs.insert("_POOL_HEADER", vec![]);
+        need_structs.insert("_POOL_HEADER", vec![
+            "struct_size",
+            "PoolType", "BlockSize", "PoolTag"
+        ]);
         need_structs.insert("_PEB", vec![]);
         need_structs.insert("_LIST_ENTRY", vec![
             "Flink", "Blink"