diff --git a/javascript/change-notes/2021-01-18-server-crash.md b/javascript/change-notes/2021-01-18-server-crash.md new file mode 100644 index 00000000000..bf5383c3bd8 --- /dev/null +++ b/javascript/change-notes/2021-01-18-server-crash.md @@ -0,0 +1,2 @@ +lgtm,codescanning +* The `js/server-crash` query has been added. It highlights servers may be terminated by a malicious user. diff --git a/javascript/config/suites/javascript/security b/javascript/config/suites/javascript/security index 3e87d292d7b..9f826d04314 100644 --- a/javascript/config/suites/javascript/security +++ b/javascript/config/suites/javascript/security @@ -49,6 +49,7 @@ + semmlecode-javascript-queries/Security/CWE-640/HostHeaderPoisoningInEmailGeneration.ql: /Security/CWE/CWE-640 + semmlecode-javascript-queries/Security/CWE-643/XpathInjection.ql: /Security/CWE/CWE-643 + semmlecode-javascript-queries/Security/CWE-730/RegExpInjection.ql: /Security/CWE/CWE-730 ++ semmlecode-javascript-queries/Security/CWE-730/ServerCrash.ql: /Security/CWE/CWE-730 + semmlecode-javascript-queries/Security/CWE-754/UnvalidatedDynamicMethodCall.ql: /Security/CWE/CWE-754 + semmlecode-javascript-queries/Security/CWE-770/MissingRateLimiting.ql: /Security/CWE/CWE-770 + semmlecode-javascript-queries/Security/CWE-776/XmlBomb.ql: /Security/CWE/CWE-776 diff --git a/javascript/ql/src/Security/CWE-730/ServerCrash.qhelp b/javascript/ql/src/Security/CWE-730/ServerCrash.qhelp new file mode 100644 index 00000000000..e46616ade47 --- /dev/null +++ b/javascript/ql/src/Security/CWE-730/ServerCrash.qhelp @@ -0,0 +1,86 @@ + + + + + +

+ + Servers handle requests from clients until terminated + deliberately by a server administrator. A client request that results + in an uncaught server-side exception causes the current server + response generation to fail, and should not have an effect on + subsequent client requests. + +

+ +

+ + Under some circumstances, uncaught exceptions can however + cause the entire server to terminate abruptly. Such a behavior is + highly undesirable, especially if it gives malicious users the ability + to turn off the server at will, which is an efficient + denial-of-service attack. + +

+ + + + + +

+ + Ensure that the processing of client requests can not cause + uncaught exceptions to terminate the entire server abruptly. + +

+ + + + + +

+ + The following server implementation checks if a client-provided + file path is valid and throws an exception if the check fails. It can + be seen that the exception is uncaught, and it is therefore reasonable to + expect the server to respond with an error response to client requests + that cause the check to fail. + + But since the exception is uncaught in the context of an + asynchronous callback invocation (fs.access(...)), the + entire server will terminate instead. + +

+ + + +

+ To remedy this, the server can catch the exception explicitly with + a try/catch block, and generate an appropriate error + response instead: + +

+ + + +

+ + An alternative is to use an async and + await for the asynchronous behavior, since the server + will then print warning messages about uncaught exceptions instead of + terminating, unless the server was started with the commandline option + --unhandled-rejections=strict: + +

+ + + + + + + + + + diff --git a/javascript/ql/src/Security/CWE-730/ServerCrash.ql b/javascript/ql/src/Security/CWE-730/ServerCrash.ql new file mode 100644 index 00000000000..b81126b33cd --- /dev/null +++ b/javascript/ql/src/Security/CWE-730/ServerCrash.ql @@ -0,0 +1,189 @@ +/** + * @name Server crash + * @description A server that can be forced to crash may be vulnerable to denial-of-service + * attacks. + * @kind path-problem + * @problem.severity warning + * @precision high + * @id js/server-crash + * @tags security + * external/cwe/cwe-730 + */ + +import javascript + +/** + * Gets a function that indirectly invokes an asynchronous callback through `async`, where the callback throws an uncaught exception at `thrower`. + */ +Function invokesCallbackThatThrowsUncaughtException( + AsyncSentinelCall async, LikelyExceptionThrower thrower +) { + async.getAsyncCallee() = throwsUncaughtExceptionInAsyncContext(thrower) and + result = async.getEnclosingFunction() + or + exists(DataFlow::InvokeNode invk, Function fun | + fun = invokesCallbackThatThrowsUncaughtException(async, thrower) and + // purposely not checking for `getEnclosingTryCatchStmt`. An async callback called from inside a try-catch can still crash the server. + result = invk.getEnclosingFunction() + | + invk.getACallee() = fun + or + // traverse a slightly extended call graph to get additional TPs + invk.(AsyncSentinelCall).getAsyncCallee() = fun + ) +} + +/** + * Gets a callee of an invocation `invk` that is not guarded by a try statement. + */ +Function getUncaughtExceptionRethrowerCallee(DataFlow::InvokeNode invk) { + not exists(invk.asExpr().getEnclosingStmt().getEnclosingTryCatchStmt()) and + result = invk.getACallee() +} + +/** + * Holds if `thrower` is not guarded by a try statement. + */ +predicate isUncaughtExceptionThrower(LikelyExceptionThrower thrower) { + not exists([thrower.(Expr).getEnclosingStmt(), thrower.(Stmt)].getEnclosingTryCatchStmt()) +} + +/** + * Gets a function that may throw an uncaught exception originating at `thrower`, which then may escape in an asynchronous calling context. + */ +Function throwsUncaughtExceptionInAsyncContext(LikelyExceptionThrower thrower) { + ( + isUncaughtExceptionThrower(thrower) and + result = thrower.getContainer() + or + exists(DataFlow::InvokeNode invk | + getUncaughtExceptionRethrowerCallee(invk) = throwsUncaughtExceptionInAsyncContext(thrower) and + result = invk.getEnclosingFunction() + ) + ) and + // Anti-case: + // An exception from an `async` function results in a rejected promise. + // Unhandled promises requires `node --unhandled-rejections=strict ...` to terminate the process + // without that flag, the DEP0018 deprecation warning is printed instead (node.js version 14 and below) + not result.isAsync() and + // pruning optimization since this predicate always is related to `invokesCallbackThatThrowsUncaughtException` + result = reachableFromAsyncCallback() +} + +/** + * Holds if `result` is reachable from a callback that is invoked asynchronously. + */ +Function reachableFromAsyncCallback() { + result instanceof AsyncCallback + or + exists(DataFlow::InvokeNode invk | + invk.getEnclosingFunction() = reachableFromAsyncCallback() and + result = invk.getACallee() + ) +} + +/** + * The main predicate of this query: used for both result display and path computation. + */ +predicate main( + HTTP::RouteHandler rh, AsyncSentinelCall async, AsyncCallback cb, LikelyExceptionThrower thrower +) { + async.getAsyncCallee() = cb and + rh.getAstNode() = invokesCallbackThatThrowsUncaughtException(async, thrower) +} + +/** + * A call that may cause a function to be invoked in an asynchronous context outside of the visible source code. + */ +class AsyncSentinelCall extends DataFlow::CallNode { + Function asyncCallee; + + AsyncSentinelCall() { + exists(DataFlow::FunctionNode node | node.getAstNode() = asyncCallee | + // manual models + exists(string memberName | + not "Sync" = memberName.suffix(memberName.length() - 4) and + this = NodeJSLib::FS::moduleMember(memberName).getACall() and + node = this.getCallback([1 .. 2]) + ) + // (add additional cases here to improve the query) + ) + } + + /** + * Gets the callee that is invoked in an asynchronous context. + */ + Function getAsyncCallee() { result = asyncCallee } +} + +/** + * A callback provided to an asynchronous call (heuristic). + */ +class AsyncCallback extends Function { + AsyncCallback() { any(AsyncSentinelCall c).getAsyncCallee() = this } +} + +/** + * A node that is likely to throw an exception. + * + * This is the primary extension point for this query. + */ +abstract class LikelyExceptionThrower extends ASTNode { } + +/** + * A `throw` statement. + */ +class TrivialThrowStatement extends LikelyExceptionThrower, ThrowStmt { } + +/** + * Empty class for avoiding emptiness checks from the compiler when there are no Expr-typed instances of the LikelyExceptionThrower type. + */ +class CompilerConfusingExceptionThrower extends LikelyExceptionThrower { + CompilerConfusingExceptionThrower() { none() } +} + +/** + * Edges that builds an explanatory graph that follows the mental model of how the the exception flows. + * + * - step 1. exception is thrown + * - step 2. exception escapes the enclosing function + * - step 3. exception follows the call graph backwards until an async callee is encountered + * - step 4. (at this point, the program crashes) + */ +query predicate edges(ASTNode pred, ASTNode succ) { + exists(LikelyExceptionThrower thrower | main(_, _, _, thrower) | + pred = thrower and + succ = thrower.getContainer() + or + exists(DataFlow::InvokeNode invk, Function fun | + fun = throwsUncaughtExceptionInAsyncContext(thrower) + | + succ = invk.getAstNode() and + pred = invk.getACallee() and + pred = fun + or + succ = fun and + succ = invk.getContainer() and + pred = invk.getAstNode() + ) + ) +} + +/** + * A node in the `edge/2` relation above. + */ +query predicate nodes(ASTNode node) { + edges(node, _) or + edges(_, node) +} + +from + HTTP::RouteHandler rh, AsyncSentinelCall async, DataFlow::Node callbackArg, AsyncCallback cb, + ExprOrStmt crasher +where + main(rh, async, cb, crasher) and + callbackArg.getALocalSource().getAstNode() = cb and + async.getAnArgument() = callbackArg +select crasher, crasher, cb, + "The server of $@ will terminate when an uncaught exception from here escapes this $@", rh, + "this route handler", callbackArg, "asynchronous callback" diff --git a/javascript/ql/src/Security/CWE-730/examples/server-crash.BAD.js b/javascript/ql/src/Security/CWE-730/examples/server-crash.BAD.js new file mode 100644 index 00000000000..9642ced4c1a --- /dev/null +++ b/javascript/ql/src/Security/CWE-730/examples/server-crash.BAD.js @@ -0,0 +1,22 @@ +const express = require("express"), + fs = require("fs"); + +function save(rootDir, path, content) { + if (!isValidPath(rootDir, req.query.filePath)) { + throw new Error(`Invalid filePath: ${req.query.filePath}`); // BAD crashes the server + } + // write content to disk +} +express().post("/save", (req, res) => { + fs.exists(rootDir, (exists) => { + if (!exists) { + console.error(`Server setup is corrupted, ${rootDir} does not exist!`); + res.status(500); + res.end(); + return; + } + save(rootDir, req.query.path, req.body); + res.status(200); + res.end(); + }); +}); diff --git a/javascript/ql/src/Security/CWE-730/examples/server-crash.GOOD-A.js b/javascript/ql/src/Security/CWE-730/examples/server-crash.GOOD-A.js new file mode 100644 index 00000000000..b23071ea53c --- /dev/null +++ b/javascript/ql/src/Security/CWE-730/examples/server-crash.GOOD-A.js @@ -0,0 +1,14 @@ +// ... +express().post("/save", (req, res) => { + fs.exists(rootDir, (exists) => { + // ... + try { + save(rootDir, req.query.path, req.body); // GOOD no uncaught exception + res.status(200); + res.end(); + } catch (e) { + res.status(500); + res.end(); + } + }); +}); diff --git a/javascript/ql/src/Security/CWE-730/examples/server-crash.GOOD-B.js b/javascript/ql/src/Security/CWE-730/examples/server-crash.GOOD-B.js new file mode 100644 index 00000000000..2a795ac001f --- /dev/null +++ b/javascript/ql/src/Security/CWE-730/examples/server-crash.GOOD-B.js @@ -0,0 +1,12 @@ +// ... +express().post("/save", async (req, res) => { + if (!(await fs.promises.exists(rootDir))) { + console.error(`Server setup is corrupted, ${rootDir} does not exist!`); + res.status(500); + res.end(); + return; + } + save(rootDir, req.query.path, req.body); // MAYBE BAD, depends on the commandline options + res.status(200); + res.end(); +}); diff --git a/javascript/ql/test/query-tests/Security/CWE-730/ServerCrash.expected b/javascript/ql/test/query-tests/Security/CWE-730/ServerCrash.expected new file mode 100644 index 00000000000..ef20a62aa9d --- /dev/null +++ b/javascript/ql/test/query-tests/Security/CWE-730/ServerCrash.expected @@ -0,0 +1,65 @@ +edges +| server-crash.js:15:5:15:14 | throw err; | server-crash.js:14:23:16:3 | (err, x ... OK\\n } | +| server-crash.js:18:1:20:1 | functio ... OT OK\\n} | server-crash.js:59:5:59:18 | indirection2() | +| server-crash.js:19:3:19:11 | throw 42; | server-crash.js:18:1:20:1 | functio ... OT OK\\n} | +| server-crash.js:24:7:24:16 | throw err; | server-crash.js:23:25:25:5 | (err, x ... K\\n } | +| server-crash.js:36:5:36:14 | throw err; | server-crash.js:35:23:37:3 | (err, x ... OK\\n } | +| server-crash.js:41:5:41:14 | throw err; | server-crash.js:40:23:42:3 | (err, x ... OK\\n } | +| server-crash.js:59:5:59:18 | indirection2() | server-crash.js:58:23:60:3 | (err, x ... ();\\n } | +| server-crash.js:88:5:88:14 | throw err; | server-crash.js:87:23:89:3 | (err, x ... OK\\n } | +| server-crash.js:94:5:94:14 | throw "e"; | server-crash.js:93:22:95:3 | () => { ... OK\\n } | +| server-crash.js:102:7:102:16 | throw "e"; | server-crash.js:101:24:103:5 | () => { ... K\\n } | +| server-crash.js:109:9:109:18 | throw "e"; | server-crash.js:108:26:110:7 | () => { ... } | +| server-crash.js:117:9:117:18 | throw "e"; | server-crash.js:116:26:118:7 | () => { ... } | +| server-crash.js:131:7:131:16 | throw err; | server-crash.js:130:25:132:5 | (err, x ... K\\n } | +| server-crash.js:152:3:154:3 | functio ... OK\\n } | server-crash.js:157:5:157:16 | throwError() | +| server-crash.js:152:3:154:3 | functio ... OK\\n } | server-crash.js:160:5:160:16 | throwError() | +| server-crash.js:152:3:154:3 | functio ... OK\\n } | server-crash.js:164:3:164:14 | throwError() | +| server-crash.js:153:5:153:22 | throw new Error(); | server-crash.js:152:3:154:3 | functio ... OK\\n } | +| server-crash.js:153:11:153:21 | new Error() | server-crash.js:152:3:154:3 | functio ... OK\\n } | +| server-crash.js:157:5:157:16 | throwError() | server-crash.js:156:3:158:3 | functio ... ath\\n } | +nodes +| server-crash.js:14:23:16:3 | (err, x ... OK\\n } | +| server-crash.js:15:5:15:14 | throw err; | +| server-crash.js:18:1:20:1 | functio ... OT OK\\n} | +| server-crash.js:19:3:19:11 | throw 42; | +| server-crash.js:23:25:25:5 | (err, x ... K\\n } | +| server-crash.js:24:7:24:16 | throw err; | +| server-crash.js:35:23:37:3 | (err, x ... OK\\n } | +| server-crash.js:36:5:36:14 | throw err; | +| server-crash.js:40:23:42:3 | (err, x ... OK\\n } | +| server-crash.js:41:5:41:14 | throw err; | +| server-crash.js:58:23:60:3 | (err, x ... ();\\n } | +| server-crash.js:59:5:59:18 | indirection2() | +| server-crash.js:87:23:89:3 | (err, x ... OK\\n } | +| server-crash.js:88:5:88:14 | throw err; | +| server-crash.js:93:22:95:3 | () => { ... OK\\n } | +| server-crash.js:94:5:94:14 | throw "e"; | +| server-crash.js:101:24:103:5 | () => { ... K\\n } | +| server-crash.js:102:7:102:16 | throw "e"; | +| server-crash.js:108:26:110:7 | () => { ... } | +| server-crash.js:109:9:109:18 | throw "e"; | +| server-crash.js:116:26:118:7 | () => { ... } | +| server-crash.js:117:9:117:18 | throw "e"; | +| server-crash.js:130:25:132:5 | (err, x ... K\\n } | +| server-crash.js:131:7:131:16 | throw err; | +| server-crash.js:152:3:154:3 | functio ... OK\\n } | +| server-crash.js:153:5:153:22 | throw new Error(); | +| server-crash.js:153:11:153:21 | new Error() | +| server-crash.js:156:3:158:3 | functio ... ath\\n } | +| server-crash.js:157:5:157:16 | throwError() | +| server-crash.js:160:5:160:16 | throwError() | +| server-crash.js:164:3:164:14 | throwError() | +#select +| server-crash.js:15:5:15:14 | throw err; | server-crash.js:15:5:15:14 | throw err; | server-crash.js:14:23:16:3 | (err, x ... OK\\n } | The server of $@ will terminate when an uncaught exception from here escapes this $@ | server-crash.js:39:25:85:1 | (req, r ... e) {}\\n} | this route handler | server-crash.js:14:23:16:3 | (err, x ... OK\\n } | asynchronous callback | +| server-crash.js:19:3:19:11 | throw 42; | server-crash.js:19:3:19:11 | throw 42; | server-crash.js:58:23:60:3 | (err, x ... ();\\n } | The server of $@ will terminate when an uncaught exception from here escapes this $@ | server-crash.js:39:25:85:1 | (req, r ... e) {}\\n} | this route handler | server-crash.js:58:23:60:3 | (err, x ... ();\\n } | asynchronous callback | +| server-crash.js:24:7:24:16 | throw err; | server-crash.js:24:7:24:16 | throw err; | server-crash.js:23:25:25:5 | (err, x ... K\\n } | The server of $@ will terminate when an uncaught exception from here escapes this $@ | server-crash.js:39:25:85:1 | (req, r ... e) {}\\n} | this route handler | server-crash.js:23:25:25:5 | (err, x ... K\\n } | asynchronous callback | +| server-crash.js:36:5:36:14 | throw err; | server-crash.js:36:5:36:14 | throw err; | server-crash.js:35:23:37:3 | (err, x ... OK\\n } | The server of $@ will terminate when an uncaught exception from here escapes this $@ | server-crash.js:39:25:85:1 | (req, r ... e) {}\\n} | this route handler | server-crash.js:35:23:37:3 | (err, x ... OK\\n } | asynchronous callback | +| server-crash.js:41:5:41:14 | throw err; | server-crash.js:41:5:41:14 | throw err; | server-crash.js:40:23:42:3 | (err, x ... OK\\n } | The server of $@ will terminate when an uncaught exception from here escapes this $@ | server-crash.js:39:25:85:1 | (req, r ... e) {}\\n} | this route handler | server-crash.js:40:23:42:3 | (err, x ... OK\\n } | asynchronous callback | +| server-crash.js:88:5:88:14 | throw err; | server-crash.js:88:5:88:14 | throw err; | server-crash.js:87:23:89:3 | (err, x ... OK\\n } | The server of $@ will terminate when an uncaught exception from here escapes this $@ | server-crash.js:39:25:85:1 | (req, r ... e) {}\\n} | this route handler | server-crash.js:87:23:89:3 | (err, x ... OK\\n } | asynchronous callback | +| server-crash.js:94:5:94:14 | throw "e"; | server-crash.js:94:5:94:14 | throw "e"; | server-crash.js:93:22:95:3 | () => { ... OK\\n } | The server of $@ will terminate when an uncaught exception from here escapes this $@ | server-crash.js:92:31:120:1 | (req, r ... });\\n} | this route handler | server-crash.js:93:22:95:3 | () => { ... OK\\n } | asynchronous callback | +| server-crash.js:102:7:102:16 | throw "e"; | server-crash.js:102:7:102:16 | throw "e"; | server-crash.js:101:24:103:5 | () => { ... K\\n } | The server of $@ will terminate when an uncaught exception from here escapes this $@ | server-crash.js:92:31:120:1 | (req, r ... });\\n} | this route handler | server-crash.js:101:24:103:5 | () => { ... K\\n } | asynchronous callback | +| server-crash.js:109:9:109:18 | throw "e"; | server-crash.js:109:9:109:18 | throw "e"; | server-crash.js:108:26:110:7 | () => { ... } | The server of $@ will terminate when an uncaught exception from here escapes this $@ | server-crash.js:92:31:120:1 | (req, r ... });\\n} | this route handler | server-crash.js:108:26:110:7 | () => { ... } | asynchronous callback | +| server-crash.js:117:9:117:18 | throw "e"; | server-crash.js:117:9:117:18 | throw "e"; | server-crash.js:116:26:118:7 | () => { ... } | The server of $@ will terminate when an uncaught exception from here escapes this $@ | server-crash.js:92:31:120:1 | (req, r ... });\\n} | this route handler | server-crash.js:116:26:118:7 | () => { ... } | asynchronous callback | +| server-crash.js:131:7:131:16 | throw err; | server-crash.js:131:7:131:16 | throw err; | server-crash.js:130:25:132:5 | (err, x ... K\\n } | The server of $@ will terminate when an uncaught exception from here escapes this $@ | server-crash.js:128:32:135:1 | async ( ... un();\\n} | this route handler | server-crash.js:130:25:132:5 | (err, x ... K\\n } | asynchronous callback | +| server-crash.js:153:5:153:22 | throw new Error(); | server-crash.js:153:5:153:22 | throw new Error(); | server-crash.js:156:3:158:3 | functio ... ath\\n } | The server of $@ will terminate when an uncaught exception from here escapes this $@ | server-crash.js:151:40:166:1 | (req, r ... nc();\\n} | this route handler | server-crash.js:161:16:161:17 | cb | asynchronous callback | diff --git a/javascript/ql/test/query-tests/Security/CWE-730/ServerCrash.qlref b/javascript/ql/test/query-tests/Security/CWE-730/ServerCrash.qlref new file mode 100644 index 00000000000..294d08cdcbb --- /dev/null +++ b/javascript/ql/test/query-tests/Security/CWE-730/ServerCrash.qlref @@ -0,0 +1 @@ +Security/CWE-730/ServerCrash.ql diff --git a/javascript/ql/test/query-tests/Security/CWE-730/server-crash.js b/javascript/ql/test/query-tests/Security/CWE-730/server-crash.js new file mode 100644 index 00000000000..cb7bc4d9b8e --- /dev/null +++ b/javascript/ql/test/query-tests/Security/CWE-730/server-crash.js @@ -0,0 +1,166 @@ +const express = require("express"); +const app = express(); +const fs = require("fs"); +const EventEmitter = require("events"); +const http = require("http"); + +const port = 12000; +let server = app.listen(port, () => + // for manual testing of the fickle node.js runtime + console.log(`Example app listening on port ${port}!`) +); + +function indirection1() { + fs.readFile("/foo", (err, x) => { + throw err; // NOT OK + }); +} +function indirection2() { + throw 42; // NOT OK +} +function indirection3() { + try { + fs.readFile("/foo", (err, x) => { + throw err; // NOT OK + }); + } catch (e) {} +} +function indirection4() { + throw 42; // OK: guarded caller +} +function indirection5() { + indirection6(); +} +function indirection6() { + fs.readFile("/foo", (err, x) => { + throw err; // NOT OK + }); +} +app.get("/async-throw", (req, res) => { + fs.readFile("/foo", (err, x) => { + throw err; // NOT OK + }); + fs.readFile("/foo", (err, x) => { + try { + throw err; // OK: guarded throw + } catch (e) {} + }); + fs.readFile("/foo", (err, x) => { + res.setHeader("reflected", req.query.header); // NOT OK [INCONSISTENCY] + }); + fs.readFile("/foo", (err, x) => { + try { + res.setHeader("reflected", req.query.header); // OK: guarded call + } catch (e) {} + }); + + indirection1(); + fs.readFile("/foo", (err, x) => { + indirection2(); + }); + + indirection3(); + try { + indirection4(); + } catch (e) {} + indirection5(); + + fs.readFile("/foo", (err, x) => { + req.query.foo; // OK + }); + fs.readFile("/foo", (err, x) => { + req.query.foo.toString(); // OK + }); + + fs.readFile("/foo", (err, x) => { + req.query.foo.bar; // NOT OK [INCONSISTENCY]: need to add property reads as sinks + }); + fs.readFile("/foo", (err, x) => { + res.setHeader("reflected", unknown); // OK + }); + + try { + indirection7(); + } catch (e) {} +}); +function indirection7() { + fs.readFile("/foo", (err, x) => { + throw err; // NOT OK + }); +} + +app.get("/async-throw-again", (req, res) => { + fs.readFile("foo", () => { + throw "e"; // NOT OK + }); + fs.readFileSync("foo", () => { + throw "e"; // OK (does not take callbacks at all) + }); + // can nest async calls (and only warns about the inner one) + fs.readFile("foo", () => { + fs.readFile("bar", () => { + throw "e"; // NOT OK + }); + }); + fs.readFile("foo", () => { + // can not catch async exceptions + try { + fs.readFile("bar", () => { + throw "e"; // NOT OK + }); + } catch (e) {} + }); + // can mix sync/async calls + fs.readFile("foo", () => { + (() => + fs.readFile("bar", () => { + throw "e"; // NOT OK + }))(); + }); +}); + +app.get("/throw-in-promise-1", async (req, res) => { + async function fun() { + throw new Error(); // OK, requires `node --unhandled-rejections=strict ...` to terminate the process + } + await fun(); +}); +app.get("/throw-in-promise-2", async (req, res) => { + async function fun() { + fs.readFile("/foo", (err, x) => { + throw err; // NOT OK + }); + } + await fun(); +}); +app.get("/throw-in-promise-3", async (req, res) => { + fs.readFile("/foo", async (err, x) => { + throw err; // OK, requires `node --unhandled-rejections=strict ...` to terminate the process + }); +}); + +app.get("/throw-in-event-emitter", async (req, res) => { + class MyEmitter extends EventEmitter {} + const myEmitter = new MyEmitter(); + myEmitter.on("event", () => { + throw new Error(); // OK, requires `node --unhandled-rejections=strict ...` to terminate the process + }); + myEmitter.emit("event"); +}); + +app.get("/throw-with-ambiguous-paths", (req, res) => { + function throwError() { + throw new Error(); // NOT OK + } + + function cb() { + throwError(); // on path + } + function withAsync() { + throwError(); // not on path + fs.stat(X, cb); + } + + throwError(); // not on path + withAsync(); +});