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Always add PT_GNU_STACK. 

If -z stack-size is given, we need to add PT_GNU_STACK even if
-z execstack is not given.

llvm-svn: 295945
This commit is contained in:
Rui Ueyama 2017-02-23 08:09:51 +00:00
parent fd939c0f6c
commit a7e87252ce
2 changed files with 31 additions and 21 deletions
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12
lld/ELF/Writer.cpp
View File

@ -1334,9 +1334,15 @@ template <class ELFT> std::vector<PhdrEntry> Writer<ELFT>::createPhdrs() {
AddHdr(PT_OPENBSD_RANDOMIZE, Sec->getPhdrFlags())->add(Sec);
// PT_GNU_STACK is a special section to tell the loader to make the
// pages for the stack non-executable.
if (!Config->ZExecstack)
AddHdr(PT_GNU_STACK, PF_R | PF_W)->p_memsz = Config->ZStackSize;
// pages for the stack non-executable. If you really want an executable
// stack, you can pass -z execstack, but that's not recommended for
// security reasons.
unsigned Perm;
if (Config->ZExecstack)
Perm = PF_R | PF_W | PF_X;
else
Perm = PF_R | PF_W;
AddHdr(PT_GNU_STACK, Perm)->p_memsz = Config->ZStackSize;
// PT_OPENBSD_WXNEEDED is a OpenBSD-specific header to mark the executable
// is expected to perform W^X violations, such as calling mprotect(2) or

40
lld/test/ELF/gnustack.s
View File

@ -5,26 +5,30 @@
# RUN: ld.lld %t1 -o %t
# RUN: llvm-readobj --program-headers -s %t | FileCheck --check-prefix=RW %s
# RW: Sections [
# RW-NOT: Name: .note.GNU-stack
# RW: ProgramHeaders [
# RW: ProgramHeader {
# RW: Type: PT_GNU_STACK
# RW-NEXT: Offset: 0x0
# RW-NEXT: VirtualAddress: 0x0
# RW-NEXT: PhysicalAddress: 0x0
# RW-NEXT: FileSize: 0
# RW-NEXT: MemSize: 0
# RW-NEXT: Flags [
# RW-NEXT: PF_R
# RW-NEXT: PF_W
# RW-NEXT: ]
# RW-NEXT: Alignment: 0
# RW-NEXT: }
# RW: Type: PT_GNU_STACK
# RW-NEXT: Offset: 0x0
# RW-NEXT: VirtualAddress: 0x0
# RW-NEXT: PhysicalAddress: 0x0
# RW-NEXT: FileSize: 0
# RW-NEXT: MemSize: 0
# RW-NEXT: Flags [
# RW-NEXT: PF_R
# RW-NEXT: PF_W
# RW-NEXT: ]
# RW-NEXT: Alignment: 0
# RWX-NOT: Name: .note.GNU-stack
# RWX-NOT: Type: PT_GNU_STACK
# RWX: Type: PT_GNU_STACK
# RWX-NEXT: Offset: 0x0
# RWX-NEXT: VirtualAddress: 0x0
# RWX-NEXT: PhysicalAddress: 0x0
# RWX-NEXT: FileSize: 0
# RWX-NEXT: MemSize: 0
# RWX-NEXT: Flags [
# RWX-NEXT: PF_R
# RWX-NEXT: PF_W
# RWX-NEXT: PF_X
# RWX-NEXT: ]
# RWX-NEXT: Alignment: 0
.globl _start
_start: