Skip to content
Merged
Show file tree
Hide file tree
Changes from all commits
Commits
File filter

Filter by extension

Filter by extension


Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
100 changes: 78 additions & 22 deletions dist/index.js
Original file line number Diff line number Diff line change
Expand Up @@ -14465,6 +14465,26 @@ var EXPANSION_MAX = 100000
// characters) so legitimate input is unaffected.
var EXPANSION_MAX_LENGTH = 4000000

// `expand` recurses once per level of brace *nesting* - both when expanding a
// set's comma members and when re-wrapping a set whose body is a single part.
// The CVE-2026-14257 fix made the *tail* iterative (recursion on `m.post`, one
// level per chained group), which left nesting depth unbounded: about 3,100
// levels of `{{{...a,b...}}}` - only ~6KB of input - exhausted the native stack
// and crashed the process. `EXPANSION_MAX_DEPTH` bounds how deep the parser
// will follow nesting. It sits far above any realistic pattern and well below
// the depth at which the stack runs out.
var EXPANSION_MAX_DEPTH = 1000

// Bash keeps a quirk where a brace group followed by a comma set still expands
// (`{a},b}`). The parser implements it by rewriting the string and restarting
// the scan, absorbing one `}` per pass. `n` trailing braces therefore cost `n`
// full passes over a string that itself grows by one `escClose` sentinel each
// time - quadratic in `n`, with a ~26x constant from the sentinel's length.
// 128KB of `'{a}' + '}'.repeat(n) + ',z}'` blocked the event loop for 27
// seconds to produce two results. `EXPANSION_MAX_REWRITES` bounds how many
// times the scan may restart. Real `{a},b}` input needs a handful.
var EXPANSION_MAX_REWRITES = 1000

function numeric(str) {
return parseInt(str, 10) == str
? parseInt(str, 10)
Expand All @@ -14488,34 +14508,54 @@ function unescapeBraces(str) {
}


// Like `target.push(...items)` but doesn't overflow the stack
function pushAll(target, items) {
for (var i = 0; i < items.length; i++) {
target.push(items[i]);
}
}

// Basically just str.split(","), but handling cases
// where we have nested braced sections, which should be
// treated as individual members, like {a,{b,c},d}
function parseCommaParts(str) {
if (!str)
return [''];

var parts = [];
var m = balanced('{', '}', str);

if (!m)
return str.split(',');
// Walk the brace groups iteratively. Recursing on `post` once per group let a
// chain of them exhaust the stack - the parsing-side counterpart to
// the `expand` overflow fixed for CVE-2026-14257, and not something `max` or
// `maxLength` can bound, since it happens before expansion.
//
// The part the next chunk continues
var carry = '';

var pre = m.pre;
var body = m.body;
var post = m.post;
var p = pre.split(',');
for (;;) {
var m = balanced('{', '}', str);

p[p.length-1] += '{' + body + '}';
var postParts = parseCommaParts(post);
if (post.length) {
p[p.length-1] += postParts.shift();
p.push.apply(p, postParts);
}
if (!m) {
var tail = str.split(',');
tail[0] = carry + tail[0];
pushAll(parts, tail);
return parts;
}

parts.push.apply(parts, p);
var pre = m.pre;
var body = m.body;
var post = m.post;
var p = pre.split(',');

return parts;
p[0] = carry + p[0];
p[p.length-1] += '{' + body + '}';

if (!post.length) {
pushAll(parts, p);
return parts;
}

carry = p.pop();
pushAll(parts, p);
str = post;
}
}

function expandTop(str, options) {
Expand All @@ -14525,6 +14565,8 @@ function expandTop(str, options) {
options = options || {};
var max = options.max == null ? EXPANSION_MAX : options.max;
var maxLength = options.maxLength == null ? EXPANSION_MAX_LENGTH : options.maxLength;
var maxDepth = options.maxDepth == null ? EXPANSION_MAX_DEPTH : options.maxDepth;
var maxRewrites = options.maxRewrites == null ? EXPANSION_MAX_REWRITES : options.maxRewrites;

// I don't know why Bash 4.3 does this, but it does.
// Anything starting with {} will have the first two bytes preserved
Expand All @@ -14536,7 +14578,7 @@ function expandTop(str, options) {
str = '\\{\\}' + str.substr(2);
}

return expand(escapeBraces(str), max, maxLength, true).map(unescapeBraces);
return expand(escapeBraces(str), max, maxLength, maxDepth, 0, maxRewrites, true).map(unescapeBraces);
}

function identity(e) {
Expand Down Expand Up @@ -14660,8 +14702,18 @@ function expand(
str,
max,
maxLength,
maxDepth,
depth,
maxRewrites,
isTop
) {
// Too deeply nested to keep following: treat the rest as literal, the same
// way a group that cannot expand is already handled. Truncating rather than
// throwing keeps expansion total, matching `max` and `maxLength`.
if (depth > maxDepth) {
return [str];
}

// Consume the string's top-level brace groups left to right, threading a
// running set of combined prefixes (`acc`). Expanding the tail iteratively -
// rather than recursing on `m.post` once per group - keeps the native stack
Expand All @@ -14682,6 +14734,9 @@ function expand(
// `accBase[a]` records how much of `acc[a]` predates the current run;
// `combine` treats an expansion as empty when it adds nothing past that.
var accBase = [0]
// How many times the `{a},b}` rewrite below has restarted the scan. Each pass
// re-reads the whole string, so leaving this unbounded is quadratic.
var rewrites = 0
var dropEmpties = false
var firstGroup = true
var nextBase
Expand Down Expand Up @@ -14713,7 +14768,8 @@ function expand(
var isOptions = m.body.indexOf(',') >= 0;
if (!isSequence && !isOptions) {
// {a},b}
if (m.post.match(/,(?!,).*\}/)) {
if (rewrites < maxRewrites && m.post.match(/,(?!,).*\}/)) {
rewrites++;
str = m.pre + '{' + m.body + escClose + m.post;
// The rewritten string is expanded as if it were a fresh top-level one,
// so start a new empty-drop run: anchor the baseline at what `acc`
Expand Down Expand Up @@ -14752,7 +14808,7 @@ function expand(
var n = parseCommaParts(m.body);
if (n.length === 1 && n[0] !== undefined) {
// x{{a,b}}y ==> x{a}y x{b}y
n = expand(n[0], max, maxLength, false).map(embrace);
n = expand(n[0], max, maxLength, maxDepth, depth + 1, maxRewrites, false).map(embrace);
//XXX is this necessary? Can't seem to hit it in tests.
/* c8 ignore start */
if (n.length === 1) {
Expand Down Expand Up @@ -14791,7 +14847,7 @@ function expand(
values = []
var valuesLength = 0
outer: for (var j = 0; j < n.length; j++) {
var expanded = expand(n[j], max, maxLength, false)
var expanded = expand(n[j], max, maxLength, maxDepth, depth + 1, maxRewrites, false)
for (var k = 0; k < expanded.length; k++) {
var v = expanded[k]
if (dropsEmpties && !v) continue
Expand Down
18 changes: 9 additions & 9 deletions package-lock.json

Some generated files are not rendered by default. Learn more about how customized files appear on GitHub.

Loading