authorgravatar for andrew@ziglang.orgAndrew Kelley <andrew@ziglang.org> 2022-06-10 17:55:17-07:00
committergravatar for andrew@ziglang.orgAndrew Kelley <andrew@ziglang.org> 2022-06-10 17:55:17-07:00
log6bf529dc381cb2f5a83c5f9e303ffdab7779ac4d
tree260738d5e702421ba7f368f3bfd31898ddc35367
parent3c3bc5af29a5fcd1daaf8d8d39625c7b505e80bf

link/wasm: fix writing past the end of debug info buffer

The function `writeDbgInfoNopsBuffered` was based on the function `pwriteDbgInfoNops`, originally written by me, and then modified to write to a memory buffer instead of an open file. When writing to a file, any extra bytes beyond the end of the file extend the size of the file, and the function body of `pwriteDbgInfoNops` takes advantage of this when `next_padding_bytes` causes the write to go beyond the end of the file. However, when writing to a memory buffer, the underlying array list must be expanded if the write would cause the buffer to expand.

1 files changed, 28 insertions(+), 26 deletions(-)

src/link/Dwarf.zig+28-26
......@@ -352,6 +352,7 @@ pub const DeclState = struct {
352352 const fields = ty.structFields();
353353 for (fields.keys()) |field_name, field_index| {
354354 const field = fields.get(field_name).?;
355 if (!field.ty.hasRuntimeBits()) continue;
355356 // DW.AT.member
356357 try dbg_info_buffer.ensureUnusedCapacity(field_name.len + 2);
357358 dbg_info_buffer.appendAssumeCapacity(@enumToInt(AbbrevKind.struct_member));
......@@ -1037,6 +1038,7 @@ pub fn commitDeclState(
10371038 }
10381039 }
10391040
1041 log.debug("updateDeclDebugInfoAllocation for '{s}'", .{decl.name});
10401042 try self.updateDeclDebugInfoAllocation(file, atom, @intCast(u32, dbg_info_buffer.items.len));
10411043
10421044 while (decl_state.abbrev_relocs.popOrNull()) |reloc| {
......@@ -1098,6 +1100,7 @@ pub fn commitDeclState(
10981100 }
10991101 }
11001102
1103 log.debug("writeDeclDebugInfo for '{s}", .{decl.name});
11011104 try self.writeDeclDebugInfo(file, atom, dbg_info_buffer.items);
11021105}
11031106
......@@ -1141,7 +1144,10 @@ fn updateDeclDebugInfoAllocation(self: *Dwarf, file: *File, atom: *Atom, len: u3
11411144 },
11421145 .wasm => {
11431146 const wasm_file = file.cast(File.Wasm).?;
1144 writeDbgInfoNopsBuffered(wasm_file.debug_info.items, atom.off, 0, &.{0}, atom.len, false);
1147 const segment_index = try wasm_file.getDebugInfoIndex();
1148 const segment = &wasm_file.segments.items[segment_index];
1149 const offset = segment.offset + atom.off;
1150 try writeDbgInfoNopsToArrayList(gpa, &wasm_file.debug_info, offset, 0, &.{0}, atom.len, false);
11451151 },
11461152 else => unreachable,
11471153 }
......@@ -1283,8 +1289,12 @@ fn writeDeclDebugInfo(self: *Dwarf, file: *File, atom: *Atom, dbg_info_buf: []co
12831289 debug_info.items.len = needed_size;
12841290 }
12851291 const offset = segment.offset + atom.off;
1286 writeDbgInfoNopsBuffered(
1287 debug_info.items,
1292 log.debug(" writeDbgInfoNopsToArrayList debug_info_len={d} offset={d} content_len={d} next_padding_size={d}", .{
1293 debug_info.items.len, offset, dbg_info_buf.len, next_padding_size,
1294 });
1295 try writeDbgInfoNopsToArrayList(
1296 gpa,
1297 debug_info,
12881298 offset,
12891299 prev_padding_size,
12901300 dbg_info_buf,
......@@ -1678,7 +1688,7 @@ pub fn writeDbgInfoHeader(self: *Dwarf, file: *File, module: *Module, low_pc: u6
16781688 },
16791689 .wasm => {
16801690 const wasm_file = file.cast(File.Wasm).?;
1681 writeDbgInfoNopsBuffered(wasm_file.debug_info.items, 0, 0, di_buf.items, jmp_amt, false);
1691 try writeDbgInfoNopsToArrayList(self.allocator, &wasm_file.debug_info, 0, 0, di_buf.items, jmp_amt, false);
16821692 },
16831693 else => unreachable,
16841694 }
......@@ -1884,35 +1894,25 @@ fn pwriteDbgInfoNops(
18841894 try file.pwritevAll(vecs[0..vec_index], offset - prev_padding_size);
18851895}
18861896
1887fn writeDbgInfoNopsBuffered(
1888 buf: []u8,
1897fn writeDbgInfoNopsToArrayList(
1898 gpa: Allocator,
1899 buffer: *std.ArrayListUnmanaged(u8),
18891900 offset: u32,
18901901 prev_padding_size: usize,
18911902 content: []const u8,
18921903 next_padding_size: usize,
18931904 trailing_zero: bool,
1894) void {
1895 assert(buf.len >= content.len + prev_padding_size + next_padding_size + @boolToInt(trailing_zero));
1896 const tracy = trace(@src());
1897 defer tracy.end();
1898
1899 {
1900 var padding_left = prev_padding_size;
1901 while (padding_left > 0) : (padding_left -= 1) {
1902 buf[offset - padding_left] = @enumToInt(AbbrevKind.pad1);
1903 }
1904 }
1905
1906 mem.copy(u8, buf[offset..], content);
1907 {
1908 var padding_left = next_padding_size;
1909 while (padding_left > 0) : (padding_left -= 1) {
1910 buf[offset + content.len + padding_left] = @enumToInt(AbbrevKind.pad1);
1911 }
1912 }
1905) Allocator.Error!void {
1906 try buffer.resize(gpa, @maximum(
1907 buffer.items.len,
1908 offset + content.len + next_padding_size + 1,
1909 ));
1910 mem.set(u8, buffer.items[offset - prev_padding_size .. offset], @enumToInt(AbbrevKind.pad1));
1911 mem.copy(u8, buffer.items[offset..], content);
1912 mem.set(u8, buffer.items[offset + content.len ..][0..next_padding_size], @enumToInt(AbbrevKind.pad1));
19131913
19141914 if (trailing_zero) {
1915 buf[offset + content.len + next_padding_size] = 0;
1915 buffer.items[offset + content.len + next_padding_size] = 0;
19161916 }
19171917}
19181918
......@@ -2249,7 +2249,9 @@ pub fn flushModule(self: *Dwarf, file: *File, module: *Module) !void {
22492249 try addDbgInfoErrorSet(arena, module, error_ty, self.target, &dbg_info_buffer);
22502250
22512251 try self.managed_atoms.append(gpa, atom);
2252 log.debug("updateDeclDebugInfoAllocation in flushModule", .{});
22522253 try self.updateDeclDebugInfoAllocation(file, atom, @intCast(u32, dbg_info_buffer.items.len));
2254 log.debug("writeDeclDebugInfo in flushModule", .{});
22532255 try self.writeDeclDebugInfo(file, atom, dbg_info_buffer.items);
22542256
22552257 const file_pos = blk: {