[lld][ELF] Improve the vulnerability in Orphan Sections initialization #156354
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Fix the error generated during the linking process when the relocation section is placed before the relocated section and the relocated section is not defined in the linker script.
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@llvm/pr-subscribers-lld Author: None (mykouHW) ChangesFix the error generated during the linking process when the relocation section is placed before the relocated section and the relocated section is not defined in the linker script. Issue Cause: If the However, during the construction and registration of the Solution: Full diff: https://github.com/llvm/llvm-project/pull/156354.diff 2 Files Affected:
diff --git a/lld/ELF/LinkerScript.cpp b/lld/ELF/LinkerScript.cpp
index 921128dae2bdb..067abbc42a13d 100644
--- a/lld/ELF/LinkerScript.cpp
+++ b/lld/ELF/LinkerScript.cpp
@@ -1037,10 +1037,14 @@ void LinkerScript::addOrphanSections() {
if (ctx.arg.relocatable && (isec->flags & SHF_LINK_ORDER))
continue;
- if (auto *sec = dyn_cast<InputSection>(isec))
- if (InputSectionBase *rel = sec->getRelocatedSection())
+ if (auto *sec = dyn_cast<InputSection>(isec)){
+ if (InputSectionBase *rel = sec->getRelocatedSection()){
+ if (auto *relIS = dyn_cast_or_null<InputSectionBase>(rel))
+ add(relIS);
if (auto *relIS = dyn_cast_or_null<InputSectionBase>(rel->parent))
add(relIS);
+ }
+ }
add(isec);
if (ctx.arg.relocatable)
for (InputSectionBase *depSec : isec->dependentSections)
diff --git a/lld/test/ELF/linkerscript/orphan-sections-init.s b/lld/test/ELF/linkerscript/orphan-sections-init.s
new file mode 100644
index 0000000000000..1701336f098e2
--- /dev/null
+++ b/lld/test/ELF/linkerscript/orphan-sections-init.s
@@ -0,0 +1,30 @@
+# REQUIRES: x86
+# RUN: rm -rf %t && mkdir -p %t
+# RUN: split-file %s %t && cd %t
+
+# RUN: llvm-mc -filetype=obj -triple=x86_64 foo.s -o foo.o
+
+# RUN: ld.lld -r foo.o -T script.ld -o foo_mc.o
+
+# RUN: llvm-objcopy --rename-section .text=.com.text foo_mc.o foo_mc.o
+# RUN: llvm-objcopy --rename-section .rela.text=.rela.com.text foo_mc.o foo_mc.o
+
+# RUN: ld.lld -r foo_mc.o -T script.ld -o foo_mc_after.o
+
+#--- foo.s
+ .text
+ .globl foo
+ .p2align 4
+ .type foo,@function
+foo:
+ mov $bar, %rax
+
+
+
+#--- script.ld
+SECTIONS
+{
+ .rela.text 0 : { *(.rela.text) }
+ .text 0 : { *(.text) }
+}
+
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@llvm/pr-subscribers-lld-elf Author: None (mykouHW) ChangesFix the error generated during the linking process when the relocation section is placed before the relocated section and the relocated section is not defined in the linker script. Issue Cause: If the However, during the construction and registration of the Solution: Full diff: https://github.com/llvm/llvm-project/pull/156354.diff 2 Files Affected:
diff --git a/lld/ELF/LinkerScript.cpp b/lld/ELF/LinkerScript.cpp
index 921128dae2bdb..067abbc42a13d 100644
--- a/lld/ELF/LinkerScript.cpp
+++ b/lld/ELF/LinkerScript.cpp
@@ -1037,10 +1037,14 @@ void LinkerScript::addOrphanSections() {
if (ctx.arg.relocatable && (isec->flags & SHF_LINK_ORDER))
continue;
- if (auto *sec = dyn_cast<InputSection>(isec))
- if (InputSectionBase *rel = sec->getRelocatedSection())
+ if (auto *sec = dyn_cast<InputSection>(isec)){
+ if (InputSectionBase *rel = sec->getRelocatedSection()){
+ if (auto *relIS = dyn_cast_or_null<InputSectionBase>(rel))
+ add(relIS);
if (auto *relIS = dyn_cast_or_null<InputSectionBase>(rel->parent))
add(relIS);
+ }
+ }
add(isec);
if (ctx.arg.relocatable)
for (InputSectionBase *depSec : isec->dependentSections)
diff --git a/lld/test/ELF/linkerscript/orphan-sections-init.s b/lld/test/ELF/linkerscript/orphan-sections-init.s
new file mode 100644
index 0000000000000..1701336f098e2
--- /dev/null
+++ b/lld/test/ELF/linkerscript/orphan-sections-init.s
@@ -0,0 +1,30 @@
+# REQUIRES: x86
+# RUN: rm -rf %t && mkdir -p %t
+# RUN: split-file %s %t && cd %t
+
+# RUN: llvm-mc -filetype=obj -triple=x86_64 foo.s -o foo.o
+
+# RUN: ld.lld -r foo.o -T script.ld -o foo_mc.o
+
+# RUN: llvm-objcopy --rename-section .text=.com.text foo_mc.o foo_mc.o
+# RUN: llvm-objcopy --rename-section .rela.text=.rela.com.text foo_mc.o foo_mc.o
+
+# RUN: ld.lld -r foo_mc.o -T script.ld -o foo_mc_after.o
+
+#--- foo.s
+ .text
+ .globl foo
+ .p2align 4
+ .type foo,@function
+foo:
+ mov $bar, %rax
+
+
+
+#--- script.ld
+SECTIONS
+{
+ .rela.text 0 : { *(.rela.text) }
+ .text 0 : { *(.text) }
+}
+
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fixes #156417
Solution:
Before processing the
RelocationSection, ensure that theOutputSectionfor theRelocatedSectionis created and registered. The creation and registration logic is protected by theaddfunction, which prevents duplicate creation. However, it may result in duplicate establishment of theparentrelationship, which does not affect correctness.