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apaznikov opened this issue Oct 29, 2024 · 0 comments
Open

Pointer: pointer variable and holding address #2

apaznikov opened this issue Oct 29, 2024 · 0 comments

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@apaznikov
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apaznikov commented Oct 29, 2024 •
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Think about address of pointer variable escapes and address holding by a pointer escapes
MorthimerMcMare pushed a commit to MorthimerMcMare/llvm-project that referenced this issue Apr 27, 2025
@rorth @tru
[sanitizer_common] Fix UnwindFast on SPARC (llvm#101634)
69555e0 
```
  UBSan-Standalone-sparc :: TestCases/Misc/Linux/diag-stacktrace.cpp
```
`FAIL`s on 32 and 64-bit Linux/sparc64 (and on Solaris/sparcv9, too: the
test isn't Linux-specific at all). With
`UBSAN_OPTIONS=fast_unwind_on_fatal=1`, the stack trace shows a
duplicate innermost frame:
```
compiler-rt/test/ubsan/TestCases/Misc/Linux/diag-stacktrace.cpp:14:31: runtime error: execution reached the end of a value-returning function without returning a value
    #0 0x7003a708 in f() compiler-rt/test/ubsan/TestCases/Misc/Linux/diag-stacktrace.cpp:14:35
    focs-lab#1 0x7003a708 in f() compiler-rt/test/ubsan/TestCases/Misc/Linux/diag-stacktrace.cpp:14:35
    focs-lab#2 0x7003a714 in g() compiler-rt/test/ubsan/TestCases/Misc/Linux/diag-stacktrace.cpp:17:38
```
which isn't seen with `fast_unwind_on_fatal=0`.

This turns out to be another fallout from fixing
`__builtin_return_address`/`__builtin_extract_return_addr` on SPARC. In
`sanitizer_stacktrace_sparc.cpp` (`BufferedStackTrace::UnwindFast`) the
`pc` arg is the return address, while `pc1` from the stack frame
(`fr_savpc`) is the address of the `call` insn, leading to a double
entry for the innermost frame in `trace_buffer[]`.

This patch fixes this by moving the adjustment before all uses.

Tested on `sparc64-unknown-linux-gnu` and `sparcv9-sun-solaris2.11`
(with the `ubsan/TestCases/Misc/Linux` tests enabled).

(cherry picked from commit 3368a32)
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