8000 linux: don't walk the rendez-vous while the linker is mid-update by schopin-mozilla · Pull Request #235 · rust-minidump/minidump-writer · GitHub
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linux: don't walk the rendez-vous while the linker is mid-update #235

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Merged
schopin-mozilla merged 1 commit into from
Sep 17, 2026
Merged

linux: don't walk the rendez-vous while the linker is mid-update #235

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8000
1 change: 1 addition & 0 deletions src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,7 @@ cfg_if::cfg_if! {
ThreadStackCopy,
CrashingThreadIpCopy,
EnumerateMappingsFromProc,
DebuggerRendezvousNotConsistent,
}
}

Expand Down
18 changes: 18 additions & 0 deletions src/linux/dso_debug.rs
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Expand Up @@ -17,6 +17,7 @@ use {
},
minidump_format::*,
},
failspot::failspot,
plain::Plain,
std::{ffi::OsString, os::unix::ffi::OsStringExt},
};
Expand Down Expand Up @@ -78,6 +79,8 @@ pub enum RendezvousError {
ReadDebuggerRendezvousAddressFailed(#[source] CopyFromProcessError),
#[error("unexpected debugger rendezvous version '{0}'")]
UnexpectedDebuggerRendezvousVersion(i32),
#[error("the dynamic linker was mid-update (r_state = {0})")]
DebuggerRendezvousNotConsistent(i32),
#[error("failed reading link_map entry")]
ReadLinkMapEntryFailed(#[source] CopyFromProcessError),
#[error("failed reading the name a link_map entry points at")]
Expand Down Expand Up @@ -241,6 +244,11 @@ pub struct LinkMap {
pub(crate) l_prev: usize,
}

/// The [`RDebug::r_state`] value stating that the mapping data is reliable.
///
/// <https://sourceware.org/git/?p=glibc.git;a=blob;f=elf/link.h;h=b645760402514c4839686aaeade20dd5bb7725dd;hb=HEAD#l52>
pub(crate) const RT_CONSISTENT: libc::c_int = 0;

/// Shared object loading information for the debugger.
///
/// The Linux dynamic linker fills this in and points the main program's
Expand Down Expand Up @@ -307,11 +315,21 @@ impl RDebug {
let debugger_rendezvous: RDebug = reader
.read_pod(address)
.map_err(RendezvousError::ReadDebuggerRendezvousAddressFailed)?;

if debugger_rendezvous.r_version != 1 {
return Err(RendezvousError::UnexpectedDebuggerRendezvousVersion(
debugger_rendezvous.r_version,
));
}

if debugger_rendezvous.r_state != RT_CONSISTENT
|| failspot!(DebuggerRendezvousNotConsistent)
{
return Err(RendezvousError::DebuggerRendezvousNotConsistent(
debugger_rendezvous.r_state,
));
}

Ok(debugger_rendezvous)
}

Expand Down
39 changes: 32 additions & 7 deletions tests/linux_module_list_failspot.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,7 @@

use {
common::*,
memmap2::Mmap,
minidump::*,
minidump_writer::{
FailSpotName,
Expand All @@ -20,25 +21,30 @@ use {

mod common;

#[test]
fn module_list_procmaps_fallback_to_rendezvous() {
let mut failspot_client = FailSpotName::testing_client();
failspot_client.set_enabled(FailSpotName::EnumerateMappingsFromProc, true);

fn make_dump_with_source(source: ModuleListSource) -> Minidump<'static, Mmap> {
let mut child = start_child_and_wait_for_threads(1);
let pid = child.id() as i32;

let mut tmpfile = tempfile::Builder::new().tempfile().unwrap();

let mut writer = MinidumpWriterConfig::new(pid, pid);
writer.set_module_list_source(ModuleListSource::ProcMaps);
writer.set_module_list_source(source);
writer.write(&mut tmpfile).unwrap();

child.kill().expect("Failed to kill process");
child.wait().expect("Failed to wait on killed process");

let dump = Minidump::read_path(tmpfile.path()).expect("failed to read minidump");
Minidump::read_path(tmpfile.path()).expect("failed to read minidump")
}

#[test]
fn module_list_procmaps_fallback_to_rendezvous() {
let mut failspot_client = FailSpotName::testing_client();
failspot_client.set_enabled(FailSpotName::EnumerateMappingsFromProc, true);

let dump = make_dump_with_source(ModuleListSource::ProcMaps);
let modules: MinidumpModuleList = dump.get_stream().expect("no module list");

let names = modules
.iter()
.map(|module| module.name.clone())
Expand All @@ -49,3 +55,22 @@ fn module_list_procmaps_fallback_to_rendezvous() {
assert_minidump_contains_soft_error(&dump, "AggregateMappingsFailed");
assert_minidump_contains_soft_error(&dump, "NoModulesInProcessMappings");
}

#[test]
fn inconsistent_debugger_rendezvous_fallback() {
let mut failspot_client = FailSpotName::testing_client();
failspot_client.set_enabled(FailSpotName::DebuggerRendezvousNotConsistent, true);

let dump = make_dump_with_source(ModuleListSource::DebuggerRendezvous);
let modules: MinidumpModuleList = dump.get_stream().expect("no module list");

let names = modules
.iter()
.map(|module| module.name.clone())
.collect::<Vec<_>>();

// Check that we have some valid data.
assert!(!names.is_empty(), "empty module list");
assert!(names.iter().any(|name| name.contains("libc")));
assert_minidump_contains_soft_error(&dump, "DebuggerRendezvousNotConsistent");
}
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