tree 1201fc7a1c7081b85eeea406cbd17b0bab047e87
parent 64f54e435e75db6a9f81f5e17511e99b2cc4bf7e
author Frederic Riss <friss@apple.com> 1500910130 -0700
committer Frederic Riss <friss@apple.com> 1500910130 -0700

[ubsan] Null-check pointers in -fsanitize=vptr (PR33881)

The instrumentation generated by -fsanitize=vptr does not null check a
user pointer before loading from it. This causes crashes in the face of
UB member calls (this=nullptr), i.e it causes user programs to crash only
after UBSan is turned on.

The fix is to make run-time null checking a prerequisite for enabling
-fsanitize=vptr, and to then teach UBSan to reuse these run-time null
checks to make -fsanitize=vptr safe.

Testing: check-clang, check-ubsan, a stage2 ubsan-enabled build
(Test updates in compiler-rt to follow in a separate patch)

https://bugs.llvm.org/show_bug.cgi?id=33881
rdar://problem/32659008