186004 2018-05-25 16:34:19 -0700 MachineContext's instructionPointer() should handle null PCs correctly. 2018-05-25 16:46:07 -0700 1 1 1 Unclassified WebKit JavaScriptCore WebKit Nightly Build Unspecified Unspecified RESOLVED FIXED InRadar P2 Normal --- 1 mark.lam mark.lam ews-watchlist keith_miller msaboff saam webkit-bug-importer oldest_to_newest 1427554 0 mark.lam 2018-05-25 16:34:19 -0700 instructionPointer() returns a MacroAssemblerCodePtr<CFunctionPtrTag>. However MacroAssemblerCodePtr's constructor does not accept a nullptr and will assert accordingly with a debug ASSERT. This is inconsequential for release builds, but to avoid this assertion failure, we should check for a null PC and return MacroAssemblerCodePtr<CFunctionPtrTag>(nullptr) instead (which uses the MacroAssemblerCodePtr(std::nullptr_t) constructor instead). Alternatively, we can change all of MacroAssemblerCodePtr's constructors to check for null pointers, but I rather not do that yet. In general, MacroAssemblerCodePtrs are constructed with non-null pointers, and I prefer to leave it that way for now. 1427556 1 mark.lam 2018-05-25 16:35:03 -0700 Note: this issue only manifests when we have signal traps enabled, and encounter a null pointer deref. 1427567 2 341354 mark.lam 2018-05-25 16:42:01 -0700 Created attachment 341354 proposed patch. 1427568 3 webkit-bug-importer 2018-05-25 16:42:53 -0700 <rdar://problem/40570067> 1427570 4 mark.lam 2018-05-25 16:46:07 -0700 Thanks for the review. Landed in r232215: <http://trac.webkit.org/r232215>. 341354 2018-05-25 16:42:01 -0700 2018-05-25 16:43:13 -0700 proposed patch. bug-186004.patch text/plain 2170 mark.lam SW5kZXg6IFNvdXJjZS9KYXZhU2NyaXB0Q29yZS9DaGFuZ2VMb2cKPT09PT09PT09PT09PT09PT09 PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PQotLS0gU291 cmNlL0phdmFTY3JpcHRDb3JlL0NoYW5nZUxvZwkocmV2aXNpb24gMjMyMjEzKQorKysgU291cmNl L0phdmFTY3JpcHRDb3JlL0NoYW5nZUxvZwkod29ya2luZyBjb3B5KQpAQCAtMSwzICsxLDI4IEBA CisyMDE4LTA1LTI1ICBNYXJrIExhbSAgPG1hcmsubGFtQGFwcGxlLmNvbT4KKworICAgICAgICBN YWNoaW5lQ29udGV4dCdzIGluc3RydWN0aW9uUG9pbnRlcigpIHNob3VsZCBoYW5kbGUgbnVsbCBQ Q3MgY29ycmVjdGx5LgorICAgICAgICBodHRwczovL2J1Z3Mud2Via2l0Lm9yZy9zaG93X2J1Zy5j Z2k/aWQ9MTg2MDA0CisKKyAgICAgICAgUmV2aWV3ZWQgYnkgTk9CT0RZIChPT1BTISkuCisKKyAg ICAgICAgaW5zdHJ1Y3Rpb25Qb2ludGVyKCkgcmV0dXJucyBhIE1hY3JvQXNzZW1ibGVyQ29kZVB0 cjxDRnVuY3Rpb25QdHJUYWc+LiAgSG93ZXZlciwKKyAgICAgICAgTWFjcm9Bc3NlbWJsZXJDb2Rl UHRyJ3MgY29uc3RydWN0b3IgZG9lcyBub3QgYWNjZXB0IGEgbnVsbCBwb2ludGVyIHZhbHVlIGFu ZCB3aWxsCisgICAgICAgIGFzc2VydCBhY2NvcmRpbmdseSB3aXRoIGEgZGVidWcgQVNTRVJULiAg VGhpcyBpcyBpbmNvbnNlcXVlbnRpYWwgZm9yIHJlbGVhc2UKKyAgICAgICAgYnVpbGRzLCBidXQg dG8gYXZvaWQgdGhpcyBhc3NlcnRpb24gZmFpbHVyZSwgd2Ugc2hvdWxkIGNoZWNrIGZvciBhIG51 bGwgUEMgYW5kCisgICAgICAgIHJldHVybiBNYWNyb0Fzc2VtYmxlckNvZGVQdHI8Q0Z1bmN0aW9u UHRyVGFnPihudWxscHRyKSBpbnN0ZWFkICh3aGljaCB1c2VzIHRoZQorICAgICAgICBNYWNyb0Fz c2VtYmxlckNvZGVQdHIoc3RkOjpudWxscHRyX3QpIHZlcnNpb24gb2YgdGhlIGNvbnN0cnVjdG9y IGluc3RlYWQpLgorCisgICAgICAgIEFsdGVybmF0aXZlbHksIHdlIGNhbiBjaGFuZ2UgYWxsIG9m IE1hY3JvQXNzZW1ibGVyQ29kZVB0cidzIGNvbnN0cnVjdG9ycyB0byBjaGVjaworICAgICAgICBm b3IgbnVsbCBwb2ludGVycywgYnV0IEkgcmF0aGVyIG5vdCBkbyB0aGF0IHlldC4gIEluIGdlbmVy YWwsCisgICAgICAgIE1hY3JvQXNzZW1ibGVyQ29kZVB0cnMgYXJlIGNvbnN0cnVjdGVkIHdpdGgg bm9uLW51bGwgcG9pbnRlcnMsIGFuZCBJIHByZWZlciB0bworICAgICAgICBsZWF2ZSBpdCB0aGF0 IHdheSBmb3Igbm93LgorCisgICAgICAgIE5vdGU6IHRoaXMgYXNzZXJ0aW9uIGZhaWx1cmUgb25s eSBtYW5pZmVzdHMgd2hlbiB3ZSBoYXZlIHNpZ25hbCB0cmFwcyBlbmFibGVkLAorICAgICAgICBh bmQgZW5jb3VudGVyIGEgbnVsbCBwb2ludGVyIGRlcmVmLgorCisgICAgICAgICogcnVudGltZS9N YWNoaW5lQ29udGV4dC5oOgorICAgICAgICAoSlNDOjpNYWNoaW5lQ29udGV4dDo6aW5zdHJ1Y3Rp b25Qb2ludGVyKToKKwogMjAxOC0wNS0yNSAgTWFyayBMYW0gIDxtYXJrLmxhbUBhcHBsZS5jb20+ CiAKICAgICAgICAgRW5mb3JjZSBpbnZhcmlhbnQgdGhhdCBHZXR0ZXJTZXR0ZXIgb2JqZWN0cyBh cmUgaW52YXJpYW50LgpJbmRleDogU291cmNlL0phdmFTY3JpcHRDb3JlL3J1bnRpbWUvTWFjaGlu ZUNvbnRleHQuaAo9PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09 PT09PT09PT09PT09PT09PT09PT09Ci0tLSBTb3VyY2UvSmF2YVNjcmlwdENvcmUvcnVudGltZS9N YWNoaW5lQ29udGV4dC5oCShyZXZpc2lvbiAyMzIyMTEpCisrKyBTb3VyY2UvSmF2YVNjcmlwdENv cmUvcnVudGltZS9NYWNoaW5lQ29udGV4dC5oCSh3b3JraW5nIGNvcHkpCkBAIC00MzgsNiArNDM4 LDggQEAgaW5saW5lIE1hY3JvQXNzZW1ibGVyQ29kZVB0cjxDRnVuY3Rpb25QdAogI2Vsc2UKICAg ICB2b2lkKiB2YWx1ZSA9IGluc3RydWN0aW9uUG9pbnRlckltcGwoY29uc3RfY2FzdDxQbGF0Zm9y bVJlZ2lzdGVycyY+KHJlZ3MpKTsKICNlbmRpZgorICAgIGlmICghdmFsdWUpCisgICAgICAgIHJl dHVybiBNYWNyb0Fzc2VtYmxlckNvZGVQdHI8Q0Z1bmN0aW9uUHRyVGFnPihudWxscHRyKTsKICAg ICByZXR1cm4gTWFjcm9Bc3NlbWJsZXJDb2RlUHRyPENGdW5jdGlvblB0clRhZz4odmFsdWUpOwog fQogCg==