| Issue |
123189
|
| Summary |
[MASM] SIGSEGV in `checkForValidSection` in MasmParser
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
MisterDA
|
I'm trying to cross-compile the OCaml compiler with a Debian host, targeting `x86_64-pc-windows` with `clang-cl`. I'm running into a segfault from `llvm-ml` (the MASM assembler), a drop-in replacement for Microsoft's `ml64`. I hit the issue with LLVM 18 and LLVM 20 (ea14bdb0356cdda727ac032470f6a0a2102d1281 as the time of writing). Here is a reproducer, as a Dockerfile (build with `docker build --platform linux/amd64 .`), and the backtrace:
```Dockerfile
# syntax=docker/dockerfile:1
FROM debian:experimental
ARG LLVM_VERSION=20
ENV DEBUGINFOD_URLS="https://debuginfod.debian.net"
RUN cat <<'EOF' > /etc/apt/sources.list.d/debug.list
deb http://deb.debian.org/debian-debug/ experimental-debug main
EOF
RUN rm -f /etc/apt/apt.conf.d/docker-clean; echo 'Binary::apt::APT::Keep-Downloaded-Packages "true";' > /etc/apt/apt.conf.d/keep-cache
RUN --mount=type=cache,target=/var/cache/apt,sharing=locked \
--mount=type=cache,target=/var/lib/apt,sharing=locked \
apt update && DEBIAN_FRONTEND=noninteractive apt upgrade -y && \
DEBIAN_FRONTEND=noninteractive apt-get --no-install-recommends install -y \
clang-$LLVM_VERSION clang-$LLVM_VERSION-dbgsym \
clang-tools-$LLVM_VERSION clang-tools-$LLVM_VERSION-dbgsym \
lld-$LLVM_VERSION lld-$LLVM_VERSION-dbgsym \
llvm-$LLVM_VERSION llvm-$LLVM_VERSION-dbgsym \
lldb-$LLVM_VERSION lldb-$LLVM_VERSION-dbgsym \
make gdb
ADD --keep-git-dir --link https://github.com/ocaml/ocaml.git /root/ocaml
WORKDIR /root/ocaml
ENV LLVM_SYMBOLIZER_PATH=/usr/bin/llvm-symbolizer-$LLVM_VERSION
RUN clang-cl-20 -nologo -EP -TC runtime/caml/domain_state.tbl > runtime/domain_state.inc
# llvm-ml-20 -m64 dislikes parentheses on macro calls
RUN sed -e 's/(//g' -e 's/)//g' -i runtime/domain_state.inc
# llvm-ml-20 doesn't understand NEAR
RUN sed -E -e 's/(EXTRN.*):.*NEAR/\1:PROC/g' -i runtime/amd64nt.asm
RUN llvm-ml-20 -m64 -nologo -Iruntime -c -Foruntime/amd64nt.obj runtime/amd64nt.asm
```
```
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.
Stack dump:
0. Program arguments: llvm-ml-20 -m64 -nologo -Iruntime -c -Foruntime/amd64nt.obj runtime/amd64nt.asm
#0 0x00007ffff7fa117a llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) build-llvm/tools/clang/stage2-bins/llvm/lib/Support/Unix/Signals.inc:723:13
#1 0x00007ffff7f9ed14 llvm::sys::RunSignalHandlers() build-llvm/tools/clang/stage2-bins/llvm/lib/Support/Signals.cpp:106:18
#2 0x00007ffff7fa182b SignalHandler build-llvm/tools/clang/stage2-bins/llvm/lib/Support/Unix/Signals.inc:413:1
#3 0x00007ffff6ac0da0 (/lib/x86_64-linux-gnu/libc.so.6+0x3fda0)
#4 0x00007ffff98923a2 checkForValidSection build-llvm/tools/clang/stage2-bins/llvm/lib/MC/MCParser/MasmParser.cpp:1457:31
#5 0x00007ffff9895133 parseStatement build-llvm/tools/clang/stage2-bins/llvm/lib/MC/MCParser/MasmParser.cpp:0:7
#6 0x00007ffff988d2a5 Run build-llvm/tools/clang/stage2-bins/llvm/lib/MC/MCParser/MasmParser.cpp:0:0
#7 0x000055555555d0f0 AssembleInput build-llvm/tools/clang/stage2-bins/llvm/tools/llvm-ml/llvm-ml.cpp:186:13
#8 0x000055555555bc9a llvm_ml_main build-llvm/tools/clang/stage2-bins/llvm/tools/llvm-ml/llvm-ml.cpp:0:11
#9 0x000055555555e45a main build-llvm/tools/clang/stage2-bins/build-llvm/tools/clang/stage2-bins/tools/llvm-ml/llvm-ml-driver.cpp:17:10
#10 0x00007ffff6aaad68 __libc_start_call_main ./csu/../sysdeps/nptl/libc_start_call_main.h:74:3
#11 0x00007ffff6aaae25 call_init ./csu/../csu/libc-start.c:128:20
#12 0x00007ffff6aaae25 __libc_start_main ./csu/../csu/libc-start.c:347:5
#13 0x0000555555559d71 (/usr/lib/llvm-20/bin/llvm-ml+0x5d71)
Segmentation fault
```
https://github.com/llvm/llvm-project/blob/628976c8345e235d4f71a0715f1990ad8b5bbcf7/llvm/lib/MC/MCParser/MasmParser.cpp#L1456-L1463
Presumably `getStreamer()` returns a `nullptr`.
It's possibly similar to #97635, I'll ping the participants: @sivan-shani @MaskRay.
Thanks for any help!
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