linux/debian/patches/bugfix/x86/x86-reject-x32-executables-...

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From: Ben Hutchings <ben@decadent.org.uk>
Date: Sat, 26 Jul 2014 15:03:11 +0100
Subject: x86: Reject x32 executables if x32 ABI not supported
Forwarded: http://mid.gmane.org/1406431195.29010.154.camel@deadeye.wl.decadent.org.uk
It is currently possible to execve() an x32 executable on an x86_64
kernel that has only ia32 compat enabled. However all its syscalls
will fail, even _exit(). This usually causes it to segfault.
Change the ELF compat architecture check so that x32 executables are
rejected if we don't support the x32 ABI.
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
arch/x86/include/asm/elf.h | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
--- a/arch/x86/include/asm/elf.h
+++ b/arch/x86/include/asm/elf.h
@@ -155,8 +155,9 @@ do { \
#define elf_check_arch(x) \
((x)->e_machine == EM_X86_64)
-#define compat_elf_check_arch(x) \
- (elf_check_arch_ia32(x) || (x)->e_machine == EM_X86_64)
+#define compat_elf_check_arch(x) \
+ (elf_check_arch_ia32(x) || \
+ (IS_ENABLED(CONFIG_X86_X32_ABI) && (x)->e_machine == EM_X86_64))
#if __USER32_DS != __USER_DS
# error "The following code assumes __USER32_DS == __USER_DS"