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[ELF] Error for executable .note.GNU-stack unless -z execstack or -r #124068

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Merged
merged 2 commits into from
Jan 23, 2025
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[ELF] Error for executable .note.GNU-stack unless -z execstack or -r #124068

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[𝘀𝗽𝗿] initial version
MaskRay Jan 23, 2025
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MaskRay Jan 23, 2025
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13 changes: 11 additions & 2 deletions lld/ELF/InputFiles.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1025,9 +1025,18 @@ InputSectionBase *ObjFile<ELFT>::createInputSection(uint32_t idx,
// Therefore, we make LLD always add PT_GNU_STACK unless it is
// explicitly told to do otherwise (by -z execstack). Because the stack
// executable-ness is controlled solely by command line options,
// .note.GNU-stack sections are simply ignored.
if (name == ".note.GNU-stack")
// .note.GNU-stack sections are, with one exception, ignored. Report
// an error if we encounter an executable .note.GNU-stack to force the
// user to explicitly request an executable stack.
if (name == ".note.GNU-stack") {
if ((sec.sh_flags & SHF_EXECINSTR) && !ctx.arg.relocatable &&
ctx.arg.zGnustack != GnuStackKind::Exec) {
Err(ctx) << this
<< ": requires an executable stack, but -z execstack is not "
"specified";
}
return &InputSection::discarded;
}

// Object files that use processor features such as Intel Control-Flow
// Enforcement (CET) or AArch64 Branch Target Identification BTI, use a
Expand Down
35 changes: 26 additions & 9 deletions lld/test/ELF/gnustack.s
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@@ -1,17 +1,20 @@
# REQUIRES: x86
# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t1
# RUN: rm -rf %t && split-file %s %t && cd %t
# RUN: llvm-mc -filetype=obj -triple=x86_64 a.s -o a.o
# RUN: llvm-mc -filetype=obj -triple=x86_64 x.s -o x.o
# RUN: llvm-mc -filetype=obj -triple=x86_64 nox.s -o nox.o

# RUN: ld.lld %t1 -z execstack -o %t
# RUN: llvm-readobj --program-headers -S %t | FileCheck --check-prefix=RWX %s
# RUN: ld.lld a.o -z execstack -o out
# RUN: llvm-readobj --program-headers -S out | FileCheck --check-prefix=RWX %s

# RUN: ld.lld %t1 -o %t
# RUN: llvm-readobj --program-headers -S %t | FileCheck --check-prefix=RW %s
# RUN: ld.lld a.o -o out
# RUN: llvm-readobj --program-headers -S out | FileCheck --check-prefix=RW %s

# RUN: ld.lld %t1 -o %t -z noexecstack
# RUN: llvm-readobj --program-headers -S %t | FileCheck --check-prefix=RW %s
# RUN: ld.lld a.o -o out -z noexecstack
# RUN: llvm-readobj --program-headers -S out | FileCheck --check-prefix=RW %s

# RUN: ld.lld %t1 -o %t -z nognustack
# RUN: llvm-readobj --program-headers -s %t | FileCheck --check-prefix=NOGNUSTACK %s
# RUN: ld.lld a.o -o out -z nognustack
# RUN: llvm-readobj --program-headers -s out | FileCheck --check-prefix=NOGNUSTACK %s

# RW: Type: PT_GNU_STACK
# RW-NEXT: Offset: 0x0
Expand Down Expand Up @@ -40,5 +43,19 @@

# NOGNUSTACK-NOT: Type: PT_GNU_STACK

# RUN: not ld.lld a.o x.o nox.o x.o 2>&1 | FileCheck %s --check-prefix=ERR --implicit-check-not=error:
# RUN: not ld.lld a.o x.o nox.o x.o -z nognustack 2>&1 | FileCheck %s --check-prefix=ERR --implicit-check-not=error:
# ERR-COUNT-2: error: x.o: requires an executable stack, but -z execstack is not specified

# RUN: ld.lld a.o x.o nox.o x.o -z execstack --fatal-warnings
# RUN: ld.lld -r x.o --fatal-warnings

#--- a.s
.globl _start
_start:

#--- x.s
.section .note.GNU-stack,"x"

#--- nox.s
.section .note.GNU-stack,""
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