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Index struct/union members within corresponding wire chunks

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This guards against access to bits outside of struct/union
members via dynamic indexing.
This commit is contained in:
Dag Lem 2023-02-28 18:45:55 +01:00
parent 79043cb849
commit 0d3423ddea
5 changed files with 68 additions and 32 deletions
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44
frontends/ast/genrtlil.cc
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@ -1375,6 +1375,7 @@ RTLIL::SigSpec AstNode::genRTLIL(int width_hint, bool sign_hint)
RTLIL::SigChunk chunk;
bool is_interface = false;
AST::AstNode *member_node = NULL;
int add_undef_bits_msb = 0;
int add_undef_bits_lsb = 0;
@ -1438,23 +1439,26 @@ RTLIL::SigSpec AstNode::genRTLIL(int width_hint, bool sign_hint)
chunk.width = wire->width;
chunk.offset = 0;
if ((member_node = get_struct_member(this))) {
// Clamp wire chunk to range of member within struct/union.
chunk.width = member_node->range_left - member_node->range_right + 1;
chunk.offset = member_node->range_right;
}
use_const_chunk:
if (children.size() != 0) {
if (children[0]->type != AST_RANGE)
log_file_error(filename, location.first_line, "Single range expected.\n");
int source_width = id2ast->range_left - id2ast->range_right + 1;
int source_offset = id2ast->range_right;
int item_left = source_width - 1;
int item_right = 0;
int chunk_left = source_width - 1;
int chunk_right = 0;
// Check for item in struct/union.
AST::AstNode *item_node;
if (attributes.count(ID::wiretype) && (item_node = attributes[ID::wiretype]) &&
(item_node->type == AST_STRUCT_ITEM || item_node->type == AST_STRUCT || item_node->type == AST_UNION))
{
// Clamp chunk to range of item within struct/union.
item_left = item_node->range_left;
item_right = item_node->range_right;
if (member_node) {
// Clamp wire chunk to range of member within struct/union.
log_assert(!source_offset && !id2ast->range_swapped);
chunk_left = chunk.offset + chunk.width - 1;
chunk_right = chunk.offset;
}
if (!children[0]->range_valid) {
@ -1468,14 +1472,16 @@ RTLIL::SigSpec AstNode::genRTLIL(int width_hint, bool sign_hint)
AstNode *fake_ast = new AstNode(AST_NONE, clone(), children[0]->children.size() >= 2 ?
children[0]->children[1]->clone() : children[0]->children[0]->clone());
fake_ast->children[0]->delete_children();
if (member_node)
fake_ast->children[0]->attributes[ID::wiretype] = member_node->clone();
int fake_ast_width = 0;
bool fake_ast_sign = true;
fake_ast->children[1]->detectSignWidth(fake_ast_width, fake_ast_sign);
RTLIL::SigSpec shift_val = fake_ast->children[1]->genRTLIL(fake_ast_width, fake_ast_sign);
if (id2ast->range_right != 0) {
shift_val = current_module->Sub(NEW_ID, shift_val, id2ast->range_right, fake_ast_sign);
if (source_offset != 0) {
shift_val = current_module->Sub(NEW_ID, shift_val, source_offset, fake_ast_sign);
fake_ast->children[1]->is_signed = true;
}
if (id2ast->range_swapped) {
@ -1491,10 +1497,10 @@ RTLIL::SigSpec AstNode::genRTLIL(int width_hint, bool sign_hint)
return sig;
} else {
chunk.width = children[0]->range_left - children[0]->range_right + 1;
chunk.offset = children[0]->range_right - source_offset;
chunk.offset += children[0]->range_right - source_offset;
if (id2ast->range_swapped)
chunk.offset = (id2ast->range_left - id2ast->range_right + 1) - (chunk.offset + chunk.width);
if (chunk.offset > item_left || chunk.offset + chunk.width < item_right) {
chunk.offset = source_width - (chunk.offset + chunk.width);
if (chunk.offset > chunk_left || chunk.offset + chunk.width < chunk_right) {
if (chunk.width == 1)
log_file_warning(filename, location.first_line, "Range select out of bounds on signal `%s': Setting result bit to undef.\n",
str.c_str());
@ -1503,12 +1509,12 @@ RTLIL::SigSpec AstNode::genRTLIL(int width_hint, bool sign_hint)
children[0]->range_left, children[0]->range_right, str.c_str(), chunk.width);
chunk = RTLIL::SigChunk(RTLIL::State::Sx, chunk.width);
} else {
if (chunk.offset + chunk.width - 1 > item_left) {
add_undef_bits_msb = (chunk.offset + chunk.width - 1) - item_left;
if (chunk.offset + chunk.width - 1 > chunk_left) {
add_undef_bits_msb = (chunk.offset + chunk.width - 1) - chunk_left;
chunk.width -= add_undef_bits_msb;
}
if (chunk.offset < item_right) {
add_undef_bits_lsb = item_right - chunk.offset;
if (chunk.offset < chunk_right) {
add_undef_bits_lsb = chunk_right - chunk.offset;
chunk.width -= add_undef_bits_lsb;
chunk.offset += add_undef_bits_lsb;
}