1695005 - selfhosted XDR decoding asserts if it cannot load file

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect, P1)

Description

[Steve Fink [:sfink] [:s:]]

js --selfhosted-xdr-path /tmp/nonexistent-file --selfhosted-xdr-mode decode -e 1
UndefinedBehaviorSanitizer:DEADLYSIGNAL
==3135389==ERROR: UndefinedBehaviorSanitizer: SEGV on unknown address 0x0000000002e4 (pc 0x5604325717ec bp 0x7fff0c7ed0c0 sp 0x7fff0c7ed0c0 T3135389)
==3135389==The signal is caused by a READ memory access.
==3135389==Hint: address points to the zero page.
    #0 0x5604325717ec in JS::Realm::isSelfHostingRealm() const /home/sfink/src/mozilla4/js/src/vm/Realm.h:508:44
    #1 0x56043254a7be in js::ErrorToException(JSContext*, JSErrorReport*, JSErrorFormatString const* (*)(void*, unsigned int), void*) /home/sfink/src/mozilla4/js/src/jsexn.cpp:294:20
    #2 0x56043266cd04 in ReportError(JSContext*, JSErrorReport*, JSErrorFormatString const* (*)(void*, unsigned int), void*) /home/sfink/src/mozilla4/js/src/vm/ErrorReporting.cpp:165:3
    #3 0x56043266d3d7 in js::ReportErrorVA(JSContext*, js::IsWarning, char const*, js::ErrorArgumentsType, __va_list_tag*) /home/sfink/src/mozilla4/js/src/vm/ErrorReporting.cpp:567:3
    #4 0x560432bef604 in JS_ReportErrorUTF8(JSContext*, char const*, ...) /home/sfink/src/mozilla4/js/src/jsapi.cpp:4739:3
    #5 0x5604321484f3 in ReadSelfHostedXDRFile(JSContext*, mozilla::Vector<unsigned char, 8ul, js::TempAllocPolicy>&) /home/sfink/src/mozilla4/js/src/shell/js.cpp:11351:5
    #6 0x560432143d1d in main /home/sfink/src/mozilla4/js/src/shell/js.cpp:12100:10
    #7 0x7fb6f199d1e1 in __libc_start_main (/lib64/libc.so.6+0x281e1)
    #8 0x5604321179fd in _start (/home/sfink/src/mozilla4/obj-debug-js/dist/bin/js+0x1ff29fd)

The problem is that it tries to report an error before the cx has entered a realm, so it seg faults when accessing cx->realm()->isSelfHostingRealm() in js::ErrorToException. Either it should fall back to printing to stderr if !cx->realm(), or it shouldn't do this via an exception in the first place.

Comment 1

[Nicolas B. Pierron [:nbp]]

Good catch!

I think I will change the code to print on stderr as you suggested, and also remove the following MOZ_CRASH such that it fallback on parsing, which I think would be a good default for testing.

Comment 2

[Nicolas B. Pierron [:nbp]]

Attachment: Bug 1695005 - ReadSelfHostedXDRFile: fallback to parsing on failure.

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/2265f1fda746
ReadSelfHostedXDRFile: fallback to parsing on failure. r=sfink

Comment 4

[Natalia Csoregi [:nataliaCs]]

https://hg.mozilla.org/mozilla-central/rev/2265f1fda746