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Revert "Merge pull request #18410 from dweiller/by-length-slice-bug"

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This reverts commit d9d840a33ac8abb0e616de862f592821a7f4a35e, reversing
changes made to a04d4330945565b8d6f298ace993f6954c42d0f3.

This is not an adequate implementation of the missing safety check, as
evidenced by the changes to std.json that are reverted in this commit.

Reopens #18382
Closes #18510
This commit is contained in:
Andrew Kelley 2024-01-13 23:20:33 -07:00
parent 0f9345ea9a
commit bd46410419
4 changed files with 0 additions and 76 deletions
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12
lib/std/json/static.zig
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@ -402,33 +402,21 @@ pub fn innerParse(
},
.partial_string_escaped_1 => |arr| {
if (i + arr.len > r.len) return error.LengthMismatch;
// tell the compiler that the by-length slice below is valid;
// this assert is required for the inequality to be comptime-known
if (arr.len > r.len) unreachable;
@memcpy(r[i..][0..arr.len], arr[0..]);
i += arr.len;
},
.partial_string_escaped_2 => |arr| {
if (i + arr.len > r.len) return error.LengthMismatch;
// tell the compiler that the by-length slice below is valid;
// this assert is required for the inequality to be comptime-known
if (arr.len > r.len) unreachable;
@memcpy(r[i..][0..arr.len], arr[0..]);
i += arr.len;
},
.partial_string_escaped_3 => |arr| {
if (i + arr.len > r.len) return error.LengthMismatch;
// tell the compiler that the by-length slice below is valid;
// this assert is required for the inequality to be comptime-known
if (arr.len > r.len) unreachable;
@memcpy(r[i..][0..arr.len], arr[0..]);
i += arr.len;
},
.partial_string_escaped_4 => |arr| {
if (i + arr.len > r.len) return error.LengthMismatch;
// tell the compiler that the by-length slice below is valid;
// this assert is required for the inequality to be comptime-known
if (arr.len > r.len) unreachable;
@memcpy(r[i..][0..arr.len], arr[0..]);
i += arr.len;
},

24
src/Sema.zig
View File

@ -32635,30 +32635,6 @@ fn analyzeSlice(
if (!end_is_len) {
const end = if (by_length) end: {
const len = try sema.coerce(block, Type.usize, uncasted_end_opt, end_src);
if (try sema.resolveValue(len)) |slice_len_val| {
const len_s_val = try mod.intValue(
Type.usize,
array_ty.arrayLenIncludingSentinel(mod),
);
if (!(try sema.compareScalar(slice_len_val, .lte, len_s_val, Type.usize))) {
const sentinel_label: []const u8 = if (array_ty.sentinel(mod) != null)
" +1 (sentinel)"
else
"";
return sema.fail(
block,
end_src,
"length {} out of bounds for array of length {}{s}",
.{
slice_len_val.fmtValue(Type.usize, mod),
len_val.fmtValue(Type.usize, mod),
sentinel_label,
},
);
}
}
// check len is less than array size if comptime known
const uncasted_end = try sema.analyzeArithmetic(block, .add, start, len, src, start_src, end_src, false);
break :end try sema.coerce(block, Type.usize, uncasted_end, end_src);
} else try sema.coerce(block, Type.usize, uncasted_end_opt, end_src);

19
test/cases/compile_errors/slice_of_array_by-length_oversized.zig
View File

@ -1,19 +0,0 @@
export fn entry1() void {
var buf: [5]u8 = undefined;
var a: u32 = 6;
_ = &a;
_ = buf[a..][0..10];
}
export fn entry2() void {
var buf: [5]u8 = undefined;
const a: u32 = 6;
_ = buf[a..][0..10];
}
// error
// backend=stage2
// target=native
//
// :5:21: error: length 10 out of bounds for array of length 5
// :11:21: error: length 10 out of bounds for array of length 5

21
test/cases/safety/array slice by-length oversized.zig
View File

@ -1,21 +0,0 @@
const std = @import("std");
pub fn panic(message: []const u8, stack_trace: ?*std.builtin.StackTrace, _: ?usize) noreturn {
_ = stack_trace;
if (std.mem.eql(u8, message, "index out of bounds: index 12, len 5")) {
std.process.exit(0);
}
std.process.exit(1);
}
pub fn main() !void {
var buf: [5]u8 = undefined;
var a: u32 = 6;
_ = &a;
_ = buf[a..][0..a];
return error.TestFailed;
}
// run
// backend=llvm
// target=native