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Differential D33712

Bug 33221 [UBSAN] segfault with -fsanitize=undefined
ClosedPublic

Authored by denis13 on May 31 2017, 1:29 AM.

Details

Reviewers
m.ostapenko
vsk
Commits
rG9af30e354151: Bug 33221 [UBSAN] segfault with -fsanitize=undefined
rCRT304437: Bug 33221 [UBSAN] segfault with -fsanitize=undefined
rL304437: Bug 33221 [UBSAN] segfault with -fsanitize=undefined
Summary

There is can be a situation when vptr is not initializing
by constructor of the object, and has a junk data which should
be properly checked, because c++ standard says:

"if default constructor is not specified
16 (7.3) no initialization is performed."

Diff Detail

Event Timeline

denis13 created this revision.May 31 2017, 1:29 AM
Herald added a subscriber: kubamracek. · View Herald TranscriptMay 31 2017, 1:29 AM
m.ostapenko edited edge metadata.May 31 2017, 1:35 AM
m.ostapenko added a subscriber: llvm-commits.

Please add a testcase (you can take it from Vedant's patch in PR).

m.ostapenko added a project: Restricted Project.May 31 2017, 1:36 AM
denis13 updated this revision to Diff 100881.May 31 2017, 10:06 AM

Test case added

vsk accepted this revision.May 31 2017, 11:38 AM

LGTM. Let me know if you'd like me to commit this for you.

This revision is now accepted and ready to land.May 31 2017, 11:38 AM
denis13 added a comment.Jun 1 2017, 12:54 AM

It would be great.
Thanks.

Closed by commit rL304437: Bug 33221 [UBSAN] segfault with -fsanitize=undefined (authored by vedantk). · Explain WhyJun 1 2017, 10:11 AM
This revision was automatically updated to reflect the committed changes.
vsk added a comment.Jun 15 2017, 11:24 AM

Just a heads-up that this necessitated a follow-up fix, see D34215 (landed in r305489).

Revision Contents

PathSize
lib/
ubsan/
2 lines

Diff 100832

lib/ubsan/ubsan_type_hash_itanium.cc

Context not available.
}; };
VtablePrefix *getVtablePrefix(void *Vtable) { VtablePrefix *getVtablePrefix(void *Vtable) {
VtablePrefix *Vptr = reinterpret_cast<VtablePrefix*>(Vtable); VtablePrefix *Vptr = reinterpret_cast<VtablePrefix*>(Vtable);
if (!Vptr) if (!IsAccessibleMemoryRange((uptr)Vptr, sizeof(VtablePrefix)))
return nullptr; return nullptr;
VtablePrefix *Prefix = Vptr - 1; VtablePrefix *Prefix = Vptr - 1;
if (!Prefix->TypeInfo) if (!Prefix->TypeInfo)
Context not available.