From cc7ff54d12d8f66c9ccda5cc2b73d974e20ee008 Mon Sep 17 00:00:00 2001
From: oddcoder <ahmedsoliman@oddcoder.com>
Date: Thu, 5 Mar 2020 18:54:26 +0200
Subject: [PATCH] Catch circular dependency when resolving loading shared
libraries
This patch implements tree-based data-structure for catching circular
dependency where libA.so will depen on arbitrarily long chain (including
zero length) of libNs.so one of which will depend on libA.so again. The
main intention of this patch was merely capturing the dependency tree to
prioterize which Elf's .init_array and which .fini_array should run
first, but as a side effect it can capture circular dependencies as well.
---
src/ld_so/linker.rs | 29 +++++++++++++++++++----------
1 file changed, 19 insertions(+), 10 deletions(-)
diff --git a/src/ld_so/linker.rs b/src/ld_so/linker.rs
index 818a5feb..b80d5d8b 100644
--- a/src/ld_so/linker.rs
+++ b/src/ld_so/linker.rs
@@ -1,6 +1,6 @@
use alloc::{
boxed::Box,
- collections::BTreeMap,
+ collections::{BTreeMap, BTreeSet},
string::{String, ToString},
vec::Vec,
};
@@ -59,6 +59,8 @@ pub struct Linker {
mmaps: BTreeMap<String, &'static mut [u8]>,
verbose: bool,
tls_index_offset: usize,
+ // used to detect circular dependencies in the Linker::load function
+ cir_dep: BTreeSet<String>,
}
impl Linker {
@@ -71,6 +73,7 @@ impl Linker {
mmaps: BTreeMap::new(),
verbose,
tls_index_offset: 0,
+ cir_dep: BTreeSet::new(),
}
}
@@ -78,6 +81,14 @@ impl Linker {
if self.verbose {
println!("load {}: {}", name, path);
}
+ if self.cir_dep.contains(name) {
+ return Err(Error::Malformed(format!(
+ "Circular dependency: {} is a dependency of itself",
+ name
+ )));
+ }
+
+ self.cir_dep.insert(name.to_string());
let mut data = Vec::new();
let path_c = CString::new(path)
@@ -91,19 +102,17 @@ impl Linker {
file.read_to_end(&mut data)
.map_err(|err| Error::Malformed(format!("failed to read '{}': {}", path, err)))?;
}
-
- self.load_data(name, data.into_boxed_slice())
+ let result = self.load_data(name, data.into_boxed_slice());
+ self.cir_dep.remove(name);
+ result
}
pub fn load_data(&mut self, name: &str, data: Box<[u8]>) -> Result<()> {
- //TODO: Prevent failures due to recursion
- {
- let elf = Elf::parse(&data)?;
- //println!("{:#?}", elf);
+ let elf = Elf::parse(&data)?;
+ //println!("{:#?}", elf);
- for library in elf.libraries.iter() {
- self.load_library(library)?;
- }
+ for library in elf.libraries.iter() {
+ self.load_library(library)?;
}
self.objects.insert(name.to_string(), data);
--
GitLab