Closed
Description
openedon Feb 21, 2021
Spawning a thread with a custom name triggers a stacked borrows violation when -Zmiri-track-raw-pointers is enabled. The root cause of the issue is that prctl only accepts integers as parameters, so Rust casts the C string pointer to an integer before passing it in but of course this doesn't work with tracked raw pointers.
Minimum reproducible example:
fn main() {
let name = std::ffi::CString::new("abc").unwrap();
unsafe { libc::prctl(libc::PR_SET_NAME, name.as_ptr() as libc::c_ulong, 0, 0, 0) };
}Output:
error: Undefined Behavior: no item granting read access to tag <untagged> at alloc1423 found in borrow stack.
--> src/main.rs:3:14
|
3 | unsafe { libc::prctl(libc::PR_SET_NAME, name.as_ptr() as libc::c_ulong, 0, 0, 0) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ no item granting read access to tag <untagged> at alloc1423 found in borrow stack.
|
= help: this indicates a potential bug in the program: it performed an invalid operation, but the rules it violated are still experimental
= help: see https://github.com/rust-lang/unsafe-code-guidelines/blob/master/wip/stacked-borrows.md for further information
= note: inside `main` at src/main.rs:3:14
= note: inside `<fn() as std::ops::FnOnce<()>>::call_once - shim(fn())` at ~/.local/share/rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ops/function.rs:227:5
= note: inside `std::sys_common::backtrace::__rust_begin_short_backtrace::<fn(), ()>` at ~/.local/share/rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/sys_common/backtrace.rs:125:18
= note: inside closure at ~/.local/share/rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/rt.rs:66:18
= note: inside `std::ops::function::impls::<impl std::ops::FnOnce<()> for &dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe>::call_once` at ~/.local/share/rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ops/function.rs:259:13
= note: inside `std::panicking::r#try::do_call::<&dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe, i32>` at ~/.local/share/rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/panicking.rs:379:40
= note: inside `std::panicking::r#try::<i32, &dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe>` at ~/.local/share/rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/panicking.rs:343:19
= note: inside `std::panic::catch_unwind::<&dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe, i32>` at ~/.local/share/rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/panic.rs:431:14
= note: inside `std::rt::lang_start_internal` at ~/.local/share/rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/rt.rs:51:25
= note: inside `std::rt::lang_start::<()>` at ~/.local/share/rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/rt.rs:65:5
Would it be possible to special-case that function for now?
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