fix: writable page should not be frozen (#142)

* fix: writable page should not be frozen

* fix: enabled in version 1 and beyond only

* test: add tests for different version0/version1

src/machine/elf_adaptor.rs

@@ -18,7 +18,7 @@ pub fn parse_elf_v1(program: &Bytes) -> Result<goblin_v034::elf::Elf, Error> {
 }
 
 /// Converts goblin's ELF flags into RISC-V flags
-pub fn convert_flags(p_flags: u32) -> Result<u8, Error> {
+pub fn convert_flags(p_flags: u32, allow_freeze_writable: bool) -> Result<u8, Error> {
     let readable = p_flags & PF_R != 0;
     let writable = p_flags & PF_W != 0;
     let executable = p_flags & PF_X != 0;
@@ -27,6 +27,8 @@ pub fn convert_flags(p_flags: u32) -> Result<u8, Error> {
     }
     if executable {
         Ok(FLAG_EXECUTABLE | FLAG_FREEZED)
+    } else if writable && !allow_freeze_writable {
+        Ok(0)
     } else {
         Ok(FLAG_FREEZED)
     }

src/machine/mod.rs

@@ -93,6 +93,7 @@ pub trait SupportMachine: CoreMachine {
         if Self::REG::BITS != elf.header.container {
             return Err(Error::InvalidElfBits);
         }
+        let version = self.version();
         let program_headers = &elf.program_headers;
         let mut bytes: u64 = 0;
         for program_header in program_headers {
@@ -110,11 +111,11 @@ pub trait SupportMachine: CoreMachine {
                 self.memory_mut().init_pages(
                     aligned_start,
                     size,
-                    elf_adaptor::convert_flags(program_header.p_flags)?,
+                    elf_adaptor::convert_flags(program_header.p_flags, version < VERSION1)?,
                     Some(program.slice(slice_start as usize..slice_end as usize)),
                     padding_start,
                 )?;
-                if self.version() < VERSION1 {
+                if version < VERSION1 {
                     self.memory_mut()
                         .store_byte(aligned_start, padding_start, 0)?;
                 }

tests/programs/writable_page.c

@@ -0,0 +1,7 @@
+#include <stdint.h>
+
+uint8_t buffer[4096] __attribute__((aligned(4096))) = {1, 2};
+
+int main() {
+    return buffer[0] + buffer[1] - 3;
+}

tests/programs/writable_page.dump

@@ -0,0 +1,99 @@
+
+writable_page:     file format elf64-littleriscv
+writable_page
+architecture: riscv:rv64, flags 0x00000112:
+EXEC_P, HAS_SYMS, D_PAGED
+start address 0x00000000000100c8
+
+Program Header:
+    LOAD off    0x0000000000000000 vaddr 0x0000000000010000 paddr 0x0000000000010000 align 2**12
+         filesz 0x00000000000004ce memsz 0x00000000000004ce flags r-x
+    LOAD off    0x00000000000004d0 vaddr 0x00000000000114d0 paddr 0x00000000000114d0 align 2**12
+         filesz 0x0000000000002290 memsz 0x00000000000022c8 flags rw-
+
+Sections:
+Idx Name          Size      VMA               LMA               File off  Algn
+  0 .text         0000041e  00000000000100b0  00000000000100b0  000000b0  2**1
+                  CONTENTS, ALLOC, LOAD, READONLY, CODE
+  1 .eh_frame     00000004  00000000000114d0  00000000000114d0  000004d0  2**2
+                  CONTENTS, ALLOC, LOAD, DATA
+  2 .init_array   00000010  00000000000114d8  00000000000114d8  000004d8  2**3
+                  CONTENTS, ALLOC, LOAD, DATA
+  3 .fini_array   00000008  00000000000114e8  00000000000114e8  000004e8  2**3
+                  CONTENTS, ALLOC, LOAD, DATA
+  4 .data         00001748  0000000000012000  0000000000012000  00001000  2**12
+                  CONTENTS, ALLOC, LOAD, DATA
+  5 .sdata        00000018  0000000000013748  0000000000013748  00002748  2**3
+                  CONTENTS, ALLOC, LOAD, DATA
+  6 .bss          00000038  0000000000013760  0000000000013760  00002760  2**3
+                  ALLOC
+  7 .comment      00000011  0000000000000000  0000000000000000  00002760  2**0
+                  CONTENTS, READONLY
+  8 .riscv.attributes 00000029  0000000000000000  0000000000000000  00002771  2**0
+                  CONTENTS, READONLY
+SYMBOL TABLE:
+00000000000100b0 l    d  .text	0000000000000000 .text
+00000000000114d0 l    d  .eh_frame	0000000000000000 .eh_frame
+00000000000114d8 l    d  .init_array	0000000000000000 .init_array
+00000000000114e8 l    d  .fini_array	0000000000000000 .fini_array
+0000000000012000 l    d  .data	0000000000000000 .data
+0000000000013748 l    d  .sdata	0000000000000000 .sdata
+0000000000013760 l    d  .bss	0000000000000000 .bss
+0000000000000000 l    d  .comment	0000000000000000 .comment
+0000000000000000 l    d  .riscv.attributes	0000000000000000 .riscv.attributes
+0000000000000000 l    df *ABS*	0000000000000000 __call_atexit.c
+00000000000100b0 l     F .text	0000000000000018 register_fini
+0000000000000000 l    df *ABS*	0000000000000000 crtstuff.c
+00000000000114d0 l     O .eh_frame	0000000000000000 
+000000000001010c l     F .text	0000000000000000 deregister_tm_clones
+0000000000010130 l     F .text	0000000000000000 register_tm_clones
+000000000001015c l     F .text	0000000000000000 __do_global_dtors_aux
+0000000000013760 l     O .bss	0000000000000001 completed.5470
+00000000000114e8 l     O .fini_array	0000000000000000 __do_global_dtors_aux_fini_array_entry
+0000000000010198 l     F .text	0000000000000000 frame_dummy
+0000000000013768 l     O .bss	0000000000000030 object.5475
+00000000000114e0 l     O .init_array	0000000000000000 __frame_dummy_init_array_entry
+0000000000000000 l    df *ABS*	0000000000000000 main.c
+0000000000000000 l    df *ABS*	0000000000000000 exit.c
+0000000000000000 l    df *ABS*	0000000000000000 impure.c
+0000000000013000 l     O .data	0000000000000748 impure_data
+0000000000000000 l    df *ABS*	0000000000000000 init.c
+0000000000000000 l    df *ABS*	0000000000000000 fini.c
+0000000000000000 l    df *ABS*	0000000000000000 atexit.c
+0000000000000000 l    df *ABS*	0000000000000000 __atexit.c
+0000000000000000 l    df *ABS*	0000000000000000 sys_exit.c
+0000000000000000 l    df *ABS*	0000000000000000 errno.c
+0000000000000000 l    df *ABS*	0000000000000000 crtstuff.c
+00000000000114d0 l     O .eh_frame	0000000000000000 __FRAME_END__
+0000000000000000 l    df *ABS*	0000000000000000 
+00000000000114f0 l       .fini_array	0000000000000000 __fini_array_end
+00000000000114e8 l       .fini_array	0000000000000000 __fini_array_start
+00000000000114e8 l       .init_array	0000000000000000 __init_array_end
+00000000000114d4 l       .eh_frame	0000000000000000 __preinit_array_end
+00000000000114d8 l       .init_array	0000000000000000 __init_array_start
+00000000000114d4 l       .eh_frame	0000000000000000 __preinit_array_start
+0000000000012f98 g       *ABS*	0000000000000000 __global_pointer$
+00000000000104c6 g     F .text	0000000000000008 __errno
+0000000000013748 g       .sdata	0000000000000000 __SDATA_BEGIN__
+0000000000013748 g     O .sdata	0000000000000000 .hidden __TMC_END__
+0000000000013750 g     O .sdata	0000000000000000 .hidden __dso_handle
+0000000000013748 g     O .sdata	0000000000000008 _global_impure_ptr
+000000000001020e g     F .text	000000000000006a __libc_init_array
+00000000000103e2 g     F .text	0000000000000034 __libc_fini_array
+0000000000010322 g     F .text	00000000000000c0 __call_exitprocs
+00000000000100c8 g     F .text	0000000000000044 _start
+0000000000010422 g     F .text	0000000000000078 __register_exitproc
+0000000000012000 g     O .data	0000000000001000 buffer
+0000000000013798 g       .bss	0000000000000000 __BSS_END__
+0000000000013760 g       .bss	0000000000000000 __bss_start
+0000000000010278 g     F .text	00000000000000aa memset
+00000000000101c2 g     F .text	000000000000002c main
+0000000000010416 g     F .text	000000000000000c atexit
+0000000000013758 g     O .sdata	0000000000000008 _impure_ptr
+0000000000012000 g       .data	0000000000000000 __DATA_BEGIN__
+0000000000013760 g       .sdata	0000000000000000 _edata
+0000000000013798 g       .bss	0000000000000000 _end
+00000000000101ee g     F .text	0000000000000020 exit
+000000000001049a g     F .text	000000000000002c _exit
+
+

tests/test_versions.rs

@@ -9,8 +9,9 @@ use ckb_vm::{
         asm::{AsmCoreMachine, AsmMachine},
         VERSION0, VERSION1,
     },
-    DefaultCoreMachine, DefaultMachine, DefaultMachineBuilder, Error, SparseMemory, WXorXMemory,
-    ISA_IMC,
+    memory::FLAG_FREEZED,
+    CoreMachine, DefaultCoreMachine, DefaultMachine, DefaultMachineBuilder, Error, Memory,
+    SparseMemory, WXorXMemory, ISA_IMC, RISCV_PAGESIZE,
 };
 use std::fs::File;
 use std::io::Read;
@@ -449,3 +450,26 @@ pub fn test_aot_version1_unaligned64() {
     assert!(result.is_ok());
     assert_eq!(result.unwrap(), 0);
 }
+
+#[test]
+pub fn test_asm_version0_writable_page() {
+    let mut machine = create_asm_machine("writable_page".to_string(), VERSION0);
+    // 0x12000 is the address of the variable "buffer", which can be found from the dump file.
+    let page_index = 0x12000 / RISCV_PAGESIZE as u64;
+    let flag = machine.machine.memory_mut().fetch_flag(page_index).unwrap();
+    assert_eq!(flag, FLAG_FREEZED);
+    let result = machine.run();
+    assert!(result.is_ok());
+    assert_eq!(result.unwrap(), 0);
+}
+
+#[test]
+pub fn test_asm_version1_writable_page() {
+    let mut machine = create_asm_machine("writable_page".to_string(), VERSION1);
+    let page_index = 0x12000 / RISCV_PAGESIZE as u64;
+    let flag = machine.machine.memory_mut().fetch_flag(page_index).unwrap();
+    assert_eq!(flag, 0);
+    let result = machine.run();
+    assert!(result.is_ok());
+    assert_eq!(result.unwrap(), 0);
+}