Re: [PATCH 3/4] configure: add flag to enable SafeStack

[Daniele Buono <dbuono@linux.vnet.ibm.com>]

Hi Stefan,

I would feel more confident by adding another check in configure to make
sure that the user didn't enable SafeStack manually through other means,
like manually setting the option through extra_cflags.
What do you think?

On 5/21/2020 5:52 AM, Stefan Hajnoczi wrote:
> On Wed, Apr 29, 2020 at 03:44:19PM -0400, Daniele Buono wrote:
>> This patch adds a flag to enable the SafeStack instrumentation provided
>> by LLVM.
>> The checks make sure that the compiler supports the flags, and that we
>> are using the proper coroutine implementation (coroutine-ucontext).
>> While SafeStack is supported only on Linux, NetBSD, FreeBSD and macOS,
>> we are not checking for the O.S. since this is already done by LLVM.
>>
>> Signed-off-by: Daniele Buono <dbuono@linux.vnet.ibm.com>
>> ---
>>   configure | 29 +++++++++++++++++++++++++++++
>>   1 file changed, 29 insertions(+)
> 
> Great, this can become Patch 1 and it can set CONFIG_SAFESTACK as
> mentioned in my earlier reply.
> 
>> diff --git a/configure b/configure
>> index 23b5e93752..f37e4ae0bd 100755
>> --- a/configure
>> +++ b/configure
>> @@ -302,6 +302,7 @@ audio_win_int=""
>>   libs_qga=""
>>   debug_info="yes"
>>   stack_protector=""
>> +safe_stack="no"
> 
> The comment above this says:
> 
>    # Always add --enable-foo and --disable-foo command line args.
> 
> Please add --disable-safe-stack.
>