Segfault on amd64 under QEMU

[lczyk]

I tried this code:

docker run -it --rm --platform=linux/amd64 ubuntu:25.04 bash -c '
apt update && apt install -y curl;
curl --proto \'=https\' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y;
. "$HOME/.cargo/env";
rustc --help'

I expected to see this happen: no segfault

Instead, this happened: segfault

note: we would appreciate a report at https://github.com/rust-lang/rust
help: you can increase rustc's stack size by setting RUST_MIN_STACK=16777216
qemu: uncaught target signal 11 (Segmentation fault) - core dumped

note: i'm on arm64 host.

reminds me of this issue which i've reported a while ago, which turned out to be an issue in upstream golang.

this is an escalation of this issue.

Meta

rustc --version --verbose: 1.90-x86_64-unknown-linux-gnu

Backtrace

/root/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/librustc_driver-890dfd19c9b338c0.so(+0x3c83a9f) [0xffffade83a9f]
/lib/x86_64-linux-gnu/libc.so.6(+0x458d0) [0xffffaa0268d0]
/root/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/bin/rustc(realloc+0xc5c) [0x55555557be2c]
/root/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/librustc_driver-890dfd19c9b338c0.so(+0x5403598) [0xffffaf603598]
/root/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/librustc_driver-890dfd19c9b338c0.so(_ZN5alloc3ffi5c_str7CString19_from_vec_unchecked17hd3132e195204e147E+0x4d) [0xffffb06ea54d]
/root/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/librustc_driver-890dfd19c9b338c0.so(_ZN118_$LT$std..thread..thread_name_string..ThreadNameString$u20$as$u20$core..convert..From$LT$alloc..string..String$GT$$GT$4from17h40ccdde012c08396E+0x49) [0xffffb06ea65d]
/root/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/librustc_driver-890dfd19c9b338c0.so(_RNvCsaeDQxODg9Sp_17rustc_driver_impl21install_ctrlc_handler+0x1da) [0xffffb070efda]
/root/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/librustc_driver-890dfd19c9b338c0.so(_RNvCsaeDQxODg9Sp_17rustc_driver_impl4main+0x15e) [0xffffb071049e]
/root/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/bin/rustc(+0x37a37) [0x55555558da37]
/root/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/bin/rustc(+0x37a23) [0x55555558da23]
/root/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/bin/rustc(+0x37a19) [0x55555558da19]
/root/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/librustc_driver-890dfd19c9b338c0.so(_ZN3std2rt19lang_start_internal17h34f9328d113fd60aE+0x491) [0xffffb077c451]
/root/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/bin/rustc(+0x74da7) [0x5555555cada7]
/lib/x86_64-linux-gnu/libc.so.6(+0x2a578) [0xffffaa00b578]
/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0x8b) [0xffffaa00b63b]
/root/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/bin/rustc(+0x74cb4) [0x5555555cacb4]

[lczyk]

Cross posted to QEMU bug tracker here as well

[lpotthast]

I got the same error trying to cross-compile on aarch64 (macOS 26) to x86_64-unknonw-linux-musl using Podman.

The compile worked fine with Docker though. As Docker now uses the Apple Virtualization Framework on macOS, this seems to be related to QEMU being in use?

RUST_MIN_STACK=16777216 CARGO_TERM_COLOR="always" CROSS_CONTAINER_ENGINE="podman" cross "build" "--profile" "production" "--target" "x86_64-unknown-linux-musl"

info: downloading component 'rust-src'
info: installing component 'rust-src'
error: process didn't exit successfully: `rustc -vV` (signal: 11, SIGSEGV: invalid memory reference)
--- stderr
error: rustc interrupted by SIGSEGV, printing backtrace

/Users/lukaspotthast/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/bin/../lib/librustc_driver-890dfd19c9b338c0.so(+0x3c83a9f)[0xffff9fe83a9f]
/lib/x86_64-linux-gnu/libpthread.so.0(+0x14420)[0xffffb18f7420]
rustc(realloc+0xc5c)[0x55555557be2c]
/Users/lukaspotthast/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/bin/../lib/librustc_driver-890dfd19c9b338c0.so(+0x5403598)[0xffffa1603598]
/Users/lukaspotthast/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/bin/../lib/librustc_driver-890dfd19c9b338c0.so(_ZN5alloc3ffi5c_str7CString19_from_vec_unchecked17hd3132e195204e147E+0x4d)[0xffffa26ea54d]
/Users/lukaspotthast/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/bin/../lib/librustc_driver-890dfd19c9b338c0.so(_ZN118_$LT$std..thread..thread_name_string..ThreadNameString$u20$as$u20$core..convert..From$LT$alloc..string..String$GT$$GT$4from17h40ccdde012c08396E+0x49)[0xffffa26ea65d]
/Users/lukaspotthast/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/bin/../lib/librustc_driver-890dfd19c9b338c0.so(_RNvCsaeDQxODg9Sp_17rustc_driver_impl21install_ctrlc_handler+0x1da)[0xffffa270efda]
/Users/lukaspotthast/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/bin/../lib/librustc_driver-890dfd19c9b338c0.so(_RNvCsaeDQxODg9Sp_17rustc_driver_impl4main+0x15e)[0xffffa271049e]
rustc(+0x37a37)[0x55555558da37]
rustc(+0x37a23)[0x55555558da23]
rustc(+0x37a19)[0x55555558da19]
/Users/lukaspotthast/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/bin/../lib/librustc_driver-890dfd19c9b338c0.so(_ZN3std2rt19lang_start_internal17h34f9328d113fd60aE+0x491)[0xffffa277c451]
rustc(+0x74da7)[0x5555555cada7]
/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf3)[0xffffb0221083]
rustc(+0x74cb4)[0x5555555cacb4]

note: we would appreciate a report at https://github.com/rust-lang/rust
help: you can increase rustc's stack size by setting RUST_MIN_STACK=16777216
qemu: uncaught target signal 11 (Segmentation fault) - core dumped

[saethlin]

I'm not sure this is an external bug. The specialization around this code path makes me worried that the wrong implementation is being selected somehow and we're not reallocating from a &'static str when we should be.