vnf,runrom: detect bad data access

This includes detection for:

- Stack underflows (it was theoretically already there but it had never
  been properly tested).
- Load/store out of bounds for a given variable known via the .nasm/
  directory.
- Load out of bounds on a set of data referenced via a raw label (see
  commit aa5174fc055d ("xixanta: Add an hint for the ending of data
  labels")).

Signed-off-by: Miquel Sabaté Solà <mssola@mssola.com>

5 files changed, 102 insertions, 0 deletions

diff --git a/tests/expected/runrom/overflow-arithmetics.txt b/tests/expected/runrom/overflow-arithmetics.txt
new file mode 100644
index 0000000..3eadfae
--- /dev/null
+++ b/tests/expected/runrom/overflow-arithmetics.txt
@@ -0,0 +1,6 @@
+<start>		PC: $8011, cycles: 7, registers: [a: $00, x: $00, y: $00, sp: $FD], status: ----I--
+ldx #$01	PC: $8013, cycles: 9, registers: [a: $00, x: $01, y: $00, sp: $FD], status: ----I--
+
+@:
+lda $0F, x	PC: $8013, cycles: 9, registers: [a: $00, x: $01, y: $00, sp: $FD], status: ----I--
+error: out of bounds: indexed access to $0010 falls out of 'zp_buffer' ($00-$10; bounded inclusively below and exclusively above)
diff --git a/tests/expected/runrom/overflow-data-indexing.txt b/tests/expected/runrom/overflow-data-indexing.txt
new file mode 100644
index 0000000..469a265
--- /dev/null
+++ b/tests/expected/runrom/overflow-data-indexing.txt
@@ -0,0 +1,10 @@
+<start>		PC: $801B, cycles: 7, registers: [a: $00, x: $00, y: $00, sp: $FD], status: ----I--
+ldx #$00	PC: $801D, cycles: 9, registers: [a: $00, x: $00, y: $00, sp: $FD], status: ----IZ-
+lda $8028, x	PC: $8020, cycles: 13, registers: [a: $00, x: $00, y: $00, sp: $FD], status: ----IZ-
+clc		PC: $8021, cycles: 15, registers: [a: $00, x: $00, y: $00, sp: $FD], status: ----IZ-
+adc #$04	PC: $8023, cycles: 17, registers: [a: $04, x: $00, y: $00, sp: $FD], status: ----I--
+tax		PC: $8024, cycles: 19, registers: [a: $04, x: $04, y: $00, sp: $FD], status: ----I--
+
+@:
+lda $8028, x	PC: $8024, cycles: 19, registers: [a: $04, x: $04, y: $00, sp: $FD], status: ----I--
+error: out of bounds: indexed access to $802C falls out of 'bad_rom_data_indexing::data' ($8028-$802C; bounded inclusively below and exclusively above)
diff --git a/tests/expected/runrom/overflow-reset.txt b/tests/expected/runrom/overflow-reset.txt
new file mode 100644
index 0000000..6097a9c
--- /dev/null
+++ b/tests/expected/runrom/overflow-reset.txt
@@ -0,0 +1,8 @@
+<start>		PC: $8000, cycles: 7, registers: [a: $00, x: $00, y: $00, sp: $FD], status: ----I--
+ldx #$00	PC: $8002, cycles: 9, registers: [a: $00, x: $00, y: $00, sp: $FD], status: ----IZ-
+lda $00, x	PC: $8004, cycles: 13, registers: [a: $00, x: $00, y: $00, sp: $FD], status: ----IZ-
+dex		PC: $8005, cycles: 15, registers: [a: $00, x: $FF, y: $00, sp: $FD], status: ----I--
+
+@:
+lda $00, x	PC: $8005, cycles: 15, registers: [a: $00, x: $FF, y: $00, sp: $FD], status: ----I--
+error: out of bounds: indexed access to $00FF falls out of 'zp_buffer' ($00-$10; bounded inclusively below and exclusively above)
diff --git a/tests/expected/runrom/overflow-stack.txt b/tests/expected/runrom/overflow-stack.txt
new file mode 100644
index 0000000..3a00e0a
--- /dev/null
+++ b/tests/expected/runrom/overflow-stack.txt
@@ -0,0 +1,6 @@
+<start>		PC: $8016, cycles: 7, registers: [a: $00, x: $00, y: $00, sp: $FD], status: ----I--
+lda #$00	PC: $8018, cycles: 9, registers: [a: $00, x: $00, y: $00, sp: $FD], status: ----IZ-
+
+@:
+pha		PC: $8018, cycles: 9, registers: [a: $00, x: $00, y: $00, sp: $FC], status: ----IZ-
+error: stack underflow!
diff --git a/tests/runrom/overflows.s b/tests/runrom/overflows.s
new file mode 100644
index 0000000..e2a5b47
--- /dev/null
+++ b/tests/runrom/overflows.s
@@ -0,0 +1,72 @@
+.segment "HEADER"
+    .byte 'N', 'E', 'S', $1A
+    .byte $02, $01
+    .byte $00
+    .byte $00
+
+.segment "CHARS"
+.byte 0
+
+.segment "VECTORS"
+    .addr reset, reset, reset
+
+.segment "CODE"
+
+zp_buffer = $00                 ; asan:reserve $10
+
+.proc reset
+    ;; Fine.
+    ldx #0
+    lda zp_buffer, x
+
+    ;; NOTE: overflow!
+    dex
+    lda zp_buffer, x
+
+    ;; Just so there are no "unused" warnings :)
+    jsr overflow_on_arithmetics
+    jsr stack_underflow
+    jsr bad_rom_data_indexing
+
+    rts
+.endproc
+
+.proc overflow_on_arithmetics
+    ;; NOTE: overflow!
+    ;; NOTE: another overflow scenario could be 'lda zp_buffer + 16, x', but
+    ;; 'nasm' can statically point this out and it will throw an error.
+    ldx #1
+    lda zp_buffer + 15, x
+
+    rts
+.endproc
+
+;; asan:stack $FD-$FF
+.proc stack_underflow
+    lda #0
+
+    ;; NOTE: stack underflow!
+    pha
+    pla
+
+    rts
+.endproc
+
+.proc bad_rom_data_indexing
+    ;; Fine.
+    ldx #0
+    lda data, x
+
+    clc
+    adc #4
+    tax
+
+    ;; NOTE: overflow!
+    lda data, x
+
+    rts
+data:
+    .byte $00, $01, $02, $03
+
+    lda zp_buffer
+.endproc