[PATCH RESEND] x86: Reject x32 executables if x32 ABI not supported

[PATCH RESEND] x86: Reject x32 executables if x32 ABI not supported

[Ben Hutchings]

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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(-)

diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h
index 1a055c8..ca3347a 100644
--- a/arch/x86/include/asm/elf.h
+++ b/arch/x86/include/asm/elf.h
@@ -160,8 +160,9 @@ 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"


-- 
Ben Hutchings
Experience is directly proportional to the value of equipment destroyed.
                                                         - Carolyn Scheppner

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Re: [PATCH RESEND] x86: Reject x32 executables if x32 ABI not supported

[Ben Hutchings]

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Can one of you please respond to this patch?

Ben.

On Sun, 2014-09-07 at 21:05 +0100, Ben Hutchings wrote:
> 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(-)
> 
> diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h
> index 1a055c8..ca3347a 100644
> --- a/arch/x86/include/asm/elf.h
> +++ b/arch/x86/include/asm/elf.h
> @@ -160,8 +160,9 @@ 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"
> 
> 

-- 
Ben Hutchings
One of the nice things about standards is that there are so many of them.

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Re: [PATCH RESEND] x86: Reject x32 executables if x32 ABI not supported

[Thomas Gleixner]

On Sat, 4 Oct 2014, Ben Hutchings wrote:

> Can one of you please respond to this patch?

Oops. Slipped through the cracks. Picked it up. Shouldn't it be tagged
for stable?

Thanks,

	tglx

Re: [PATCH RESEND] x86: Reject x32 executables if x32 ABI not supported

[Ben Hutchings]

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On Sun, 2014-10-05 at 23:30 +0200, Thomas Gleixner wrote:
> On Sat, 4 Oct 2014, Ben Hutchings wrote:
> 
> > Can one of you please respond to this patch?
> 
> Oops. Slipped through the cracks. Picked it up. Shouldn't it be tagged
> for stable?

Right.  Please add:

Fixes: d1a797f388d6 ("x32: Handle process creation")
Cc: <stable@vger.kernel.org> # v3.4+

Ben.

-- 
Ben Hutchings
Klipstein's 4th Law of Prototyping and Production:
                                    A fail-safe circuit will destroy others.

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[tip:x86/urgent] x86: Reject x32 executables if x32 ABI not supported

[tip-bot for Ben Hutchings]

Commit-ID:  0e6d3112a4e95d55cf6dca88f298d5f4b8f29bd1
Gitweb:     http://git.kernel.org/tip/0e6d3112a4e95d55cf6dca88f298d5f4b8f29bd1
Author:     Ben Hutchings <ben@decadent.org.uk>
AuthorDate: Sun, 7 Sep 2014 21:05:05 +0100
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Wed, 8 Oct 2014 11:17:42 +0200

x86: Reject x32 executables if x32 ABI not supported

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>
Link: http://lkml.kernel.org/r/1410120305.6822.9.camel@decadent.org.uk
Cc: stable@vger.kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 arch/x86/include/asm/elf.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h
index 1a055c8..ca3347a 100644
--- a/arch/x86/include/asm/elf.h
+++ b/arch/x86/include/asm/elf.h
@@ -160,8 +160,9 @@ 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"