[PATCH olang] fix: codegen: prevent stack overwrite

[PATCH olang] fix: codegen: prevent stack overwrite

[Carlos Maniero]

There was an issue in the stack allocation algorithm. Consider this
function:

  fn a(): u32 {
    var a: u32 = 0xAAAA
    var b: u64 = 0xBBBBBBBB

    ret
  }

There are three information the stack is required to store:

- 8 bytes: rip (from call instruction)
- 4 bytes: a
- 8 bytes: b

The 0x7FFFFF07 memory address was used to represent the RIP value at
call instant.

Our codegen was assuming the stack works that way:

0       -8  -C
^-------^---^-------
7FFFFF07AAAABBBBBBBB
^-------^---^-------
rip     a   b

So the code gen was:

- Adding the value at the stack;
- Increasing the offset.

But actually the stack was behaving as following:

8       0       -8  -C
^-------^-------^---^
7FFFFF070000BBBBBBBB.
^---------------^---^
rip             a   b

Once the instruction *mov %rax, -0xC(%rbp)* writes from -0xC(%rbp)
(exclusive) to -0x4(%rbp) (inclusive).

So after this change, this is the actual stack template:

        0   -4      -C
--------^---^-------^
7FFFFF07AAAABBBBBBBB.
--------^---^-------^
      rip   a       b

Signed-off-by: Carlos Maniero <carlos@maniero.me>
---
 src/codegen_linux_x86_64.c          | 13 ++++++-------
 tests/olc/0036_variable_overflow.ol | 30 +++++++++++++++++++++++++++++
 2 files changed, 36 insertions(+), 7 deletions(-)
 create mode 100644 tests/olc/0036_variable_overflow.ol

diff --git a/src/codegen_linux_x86_64.c b/src/codegen_linux_x86_64.c
index fc8fcc4..83d1d2c 100644
--- a/src/codegen_linux_x86_64.c
+++ b/src/codegen_linux_x86_64.c
@@ -28,7 +28,6 @@
 
 // The call instruction pushes EIP into stack so the first 8 bytes from stack
 // must be preserved else the ret instruction will jump to nowere.
-#define X86_CALL_EIP_STACK_OFFSET (8)
 #define X86_CALL_ARG_SIZE 6
 
 #define bytes_max(a, b) ((a) > (b) ? (a) : (b))
@@ -795,6 +794,9 @@ codegen_linux_x86_64_emit_block(codegen_x86_64_t *codegen, ast_block_t *block)
                 symbol_t *symbol = scope_lookup(scope, var_def.id);
                 assert(symbol);
 
+                size_t type_size = type_to_bytes(symbol->type);
+                codegen->base_offset += type_size;
+
                 codegen_linux_x86_64_put_stack_offset(
                     codegen, symbol, codegen->base_offset);
 
@@ -803,13 +805,10 @@ codegen_linux_x86_64_emit_block(codegen_x86_64_t *codegen, ast_block_t *block)
                                                          var_def.value);
                 }
 
-                size_t type_size = type_to_bytes(symbol->type);
-
                 fprintf(codegen->out,
                         "    mov %s, -%ld(%%rbp)\n",
                         get_reg_for(REG_ACCUMULATOR, type_size),
                         codegen->base_offset);
-                codegen->base_offset += type_size;
 
                 break;
             }
@@ -957,7 +956,7 @@ static void
 codegen_linux_x86_64_emit_function(codegen_x86_64_t *codegen,
                                    ast_fn_definition_t *fn_def)
 {
-    codegen->base_offset = X86_CALL_EIP_STACK_OFFSET;
+    codegen->base_offset = 0;
 
     ast_node_t *block_node = fn_def->block;
     fprintf(codegen->out, "" SV_FMT ":\n", SV_ARG(fn_def->id));
@@ -975,6 +974,8 @@ codegen_linux_x86_64_emit_function(codegen_x86_64_t *codegen,
         symbol_t *symbol = scope_lookup(fn_def->scope, param->id);
         assert(symbol);
 
+        // FIXME: add offset according to the param size
+        codegen->base_offset += 8;
         size_t offset = codegen->base_offset;
 
         codegen_linux_x86_64_put_stack_offset(
@@ -986,8 +987,6 @@ codegen_linux_x86_64_emit_function(codegen_x86_64_t *codegen,
                 get_reg_for(x86_call_args[i], symbol->type->as_primitive.size),
                 offset);
 
-        // FIXME: add offset according to the param size
-        codegen->base_offset += 8;
         ++i;
     }
 
diff --git a/tests/olc/0036_variable_overflow.ol b/tests/olc/0036_variable_overflow.ol
new file mode 100644
index 0000000..edb3c7e
--- /dev/null
+++ b/tests/olc/0036_variable_overflow.ol
@@ -0,0 +1,30 @@
+# Copyright (C) 2024 olang mantainers
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+fn main(): u32 {
+  var a: u32 = 0
+  var b: u64 = 0
+  var c: u32 = 0
+
+  # This operation will fill all bits in b location.
+  # If there is an overflow, both a or c would be impacted
+  b = ~b
+
+  return a + c
+}
+
+# TEST test_compile(exit_code=0)
+
+# TEST test_run_binary(exit_code=0)

base-commit: cf5e4abf07a38f0ddf3ac6979b01b942ab99a691
-- 
2.46.1

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 28s

[fix: codegen: prevent stack overwrite][0] from [Carlos Maniero][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/55483
[1]: mailto:carlos@maniero.me

✗ #1350731 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1350731

Re: [olang/patches/.build.yml] build failed

[Carlos Maniero]

There is an issue unrelated to my changes. The spec that does not allows
comments inside.

I sent another patch [1] that will fix the spec.

[1]: Message-ID: <20241015225750.211129-2-carlos@maniero.me>.

Re: [PATCH olang] fix: codegen: prevent stack overwrite

[Johnny Richard]

Thanks. applied!

Lovely patch description by the way <3

Build started: https://builds.sr.ht/~johnnyrichard/job/1352096

To git.sr.ht:~johnnyrichard/olang
   f0c9d1c..df8420f  main -> main

Re: [olang/patches/.build.yml] build failed

[Carlos Maniero]

I broke the format :(

I'll wait for the review before submitting a v2.

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 20s

[deref operation returning value][0] from [Carlos Maniero][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/55515
[1]: mailto:carlos@maniero.me

✗ #1352279 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1352279

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 21s

[fix: build: add missing dependencies for check-spec][0] from [Johnny Richard][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/55427
[1]: mailto:johnny@johnnyrichard.com

✗ #1348643 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1348643

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 18s

[parser: conform block line feeds with the spec][0] from [Carlos Maniero][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/55389
[1]: mailto:carlos@maniero.me

✗ #1346505 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1346505

Re: [olang/patches/.build.yml] build failed

[Johnny Richard]

My bad... I have made these changes on top of patches not applied on
main branch.

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 29s

[refactor: ast: inline union typedefs][0] from [Johnny Richard][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/54446
[1]: mailto:johnny@johnnyrichard.com

✗ #1302361 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1302361

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 39s

[build: rename linter to format to avoid confusion][0] from [Johnny Richard][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/51175
[1]: mailto:johnny@johnnyrichard.com

✗ #1200225 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1200225

Re: [olang/patches/.build.yml] build failed

[Johnny Richard]

On Thu, Mar 28, 2024 at 02:59:02PM +0000, builds.sr.ht wrote:
> olang/patches/.build.yml: FAILED in 36s
> 
> [fe: lexer: add single line comments support][0] from [Johnny Richard][1]
> 
> [0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/50503
> [1]: mailto:johnny@johnnyrichard.com
> 
> ✗ #1181030 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1181030

This build is failing due to a clang bumped version on Arch Linux
repositories.  It was a major bump from 16 to 17 (it has breaking
changes).

We can solve this problem by fixing the version or by bumping our clang
locally.  I will upgrade my clang meanwhile.

Please, consider the patch to fix it.

---->8----
Subject: [PATCH olang] fixup! fe: lexer: add single line comments support


diff --git a/src/pretty_print_ast.c b/src/pretty_print_ast.c
index e950796..129f090 100644
--- a/src/pretty_print_ast.c
+++ b/src/pretty_print_ast.c
@@ -26,7 +26,7 @@
 
 #define ANSI_COLOR_MAGENTA "\x1b[35m"
 #define ANSI_COLOR_RESET "\x1b[0m"
-#define PP_IS_BIT_SET(data, index) ((data)&1 << index)
+#define PP_IS_BIT_SET(data, index) ((data) & 1 << index)
 
 typedef struct pretty_print_node
 {

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 36s

[fe: lexer: add single line comments support][0] from [Johnny Richard][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/50503
[1]: mailto:johnny@johnnyrichard.com

✗ #1181030 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1181030

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 35s

[docs: variables specification][0] from [Carlos Maniero][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/50474
[1]: mailto:carlos@maniero.me

✗ #1179573 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1179573

Re: [olang/patches/.build.yml] build failed

[Carlos Maniero]

oops!

s/see/be

Re: [olang/patches/.build.yml] build failed

[Carlos Maniero]

The failed pipeline seems to see a sourcehut issue.

Tested locally and all fine.

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 40s

[Introduce CLI option for improved AST tree visualization][0] from [Johnny Richard][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/50448
[1]: mailto:johnny@johnnyrichard.com

✗ #1178386 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1178386

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 31s

[refactor: rename zero programming language to olang][0] v3 from [Fabio Maciel][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/50187
[1]: mailto:fabio@fabiomaciel.com

✗ #1167852 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1167852

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 30s

[parser: abort when parser identifies a syntax error][0] from [Johnny Richard][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/50088
[1]: mailto:johnny@johnnyrichard.com

✗ #1164684 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1164684

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 12s

[implement assembly linux x86_64 compiler][0] v2 from [Johnny Richard][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/49994
[1]: mailto:johnny@johnnyrichard.com

✗ #1162085 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1162085

Re: [olang/patches/.build.yml] build failed

[Carlos Maniero]

The checks passed just fine in my environment too.

Re: [olang/patches/.build.yml] build failed

[Johnny Richard]

On Mon, Mar 04, 2024 at 06:33:31PM +0000, builds.sr.ht wrote:
> olang/patches/.build.yml: FAILED in 12s
> 
> [implement assembly linux x86_64 compiler][0] from [Johnny Richard][1]
> 
> [0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/49981
> [1]: mailto:johnny@johnnyrichard.com
> 
> ✗ #1161742 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1161742

I not sure what is happening, the build works find on my machine.  Looks
like the CI machines are failing to setup the environment, nothing to do
with my changes I believe:

    [#1161745] 2024/03/04 18:36:41 Booting image archlinux (default) on port 22563
    [#1161745] 2024/03/04 18:36:42 Waiting for guest to settle
    [#1161745] 2024/03/04 18:36:49 Sending tasks
    [#1161745] 2024/03/04 18:36:52 Sending build environment
    [#1161745] 2024/03/04 18:36:53 Installing packages
    Warning: Permanently added '[localhost]:22563' (ED25519) to the list of known hosts.
    :: Synchronizing package databases...
     core downloading...
     extra downloading...
     multilib downloading...
    warning: archlinux-keyring-20240208-1 is up to date -- skipping
     there is nothing to do
    Warning: Permanently added '[localhost]:22563' (ED25519) to the list of known hosts.
    error: missing dependency 'initramfs' for package 'linux'
    linux: ignoring package upgrade (6.7.6.arch1-1 => 6.7.8.arch1-1)
    mkinitcpio: ignoring package upgrade (37.3-1 => 38-3)
    Resolving dependencies...
    Checking package conflicts...
    :: uninstalling package 'mkinitcpio-37.3-1' due to conflict with 'cryptsetup-2.7.0-3'
    [#1161745] 2024/03/04 18:36:54 Processing post-failed triggers...
    [#1161745] 2024/03/04 18:36:54 Sending webhook...
    [#1161745] 2024/03/04 18:36:54 Webhook response: 200
    [#1161745] 2024/03/04 18:36:54 Thanks!
    [#1161745] 2024/03/04 18:36:54 Build failed.
    [#1161745] 2024/03/04 18:36:54 The build environment will be kept alive for 10 minutes.
    [#1161745] 2024/03/04 18:36:54 To log in with SSH and examine it, use the following command:
    [#1161745] 2024/03/04 18:36:54
    [#1161745] 2024/03/04 18:36:54 	ssh -t builds@fra02.builds.sr.ht connect 1161745
    [#1161745] 2024/03/04 18:36:54
    [#1161745] 2024/03/04 18:36:54 After logging in, the deadline is increased to your remaining build time.

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 12s

[implement assembly linux x86_64 compiler][0] from [Johnny Richard][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/49981
[1]: mailto:johnny@johnnyrichard.com

✗ #1161742 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1161742

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 36s

[string_view: fix stack buffer overflow on to_u32][0] from [Johnny Richard][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/49949
[1]: mailto:johnny@johnnyrichard.com

✗ #1160713 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1160713

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 40s

[string_view: add n + 1 test to string_view_to_u32 function][0] from [Johnny Richard][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/49946
[1]: mailto:johnny@johnnyrichard.com

✗ #1160663 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1160663

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 36s

[utils: add arena][0] v2 from [Carlos Maniero][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/49708
[1]: mailto:carlos@maniero.me

✗ #1154158 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1154158

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 36s

[utils: add arena][0] from [Carlos Maniero][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/49707
[1]: mailto:carlos@maniero.me

✗ #1154146 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1154146

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 42s

[Create --dump-tokens on compiler cli][0] v4 from [Johnny Richard][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/49682
[1]: mailto:johnny@johnnyrichard.com

✗ #1153624 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1153624

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 34s

[Create --dump-tokens on compiler cli][0] v2 from [Johnny Richard][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/49641
[1]: mailto:johnny@johnnyrichard.com

✗ #1153051 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1153051

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 31s

[Create --dump-tokens on compiler cli][0] from [Johnny Richard][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/49640
[1]: mailto:johnny@johnnyrichard.com

✗ #1153048 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1153048

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 18s

[remove sphinx dependency][0] from [Carlos Maniero][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/49598
[1]: mailto:carlos@maniero.me

✗ #1151949 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1151949

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 19s

[docs: add HACKING documentation][0] from [Carlos Maniero][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/49586
[1]: mailto:carlos@maniero.me

✗ #1151773 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1151773

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 15s

[Add integration tests][0] v2 from [Carlos Maniero][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/49556
[1]: mailto:carlos@maniero.me

✗ #1151085 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1151085

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 16s

[style: fix clang-format format indentation][0] from [Carlos Maniero][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/49522
[1]: mailto:carlos@maniero.me

✗ #1150343 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1150343

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 13s

[build: enable continuous integration through .build.yml][0] from [Johnny Richard][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/49459
[1]: mailto:johnny@johnnyrichard.com

✗ #1149170 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1149170