Re: [Qemu-trivial] [Qemu-devel] [PATCH] coroutine-sigaltstack: Change jmp_buf to sigjmp_buf

[Markus Armbruster]

Peter Maydell <address@hidden> writes:

> On 8 November 2014 03:51, Willem Pinckaers <address@hidden> wrote:
>> This is a simple patch to change the type of old_env from jmp_buf
>> to sigjmp_buf.  old_env is used by sigsetjmp and as such should be
>> a sigjmp_buf.
>>
>> This fixes a stack_chk fail in a OSX 32bit build. Since at least on
>> OSX sigjmp_buf is four bytes larger then a jmpbuf, resulting in an
>> overflow in sigsetjmp. Due to variable reordering this overwrites
>> the stack cookie.
>>
>> Signed-off-by: Willem Pinckaers <address@hidden>
>> ---
>>  coroutine-sigaltstack.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/coroutine-sigaltstack.c b/coroutine-sigaltstack.c
>> index 3de0bb3..63519ff 100644
>> --- a/coroutine-sigaltstack.c
>> +++ b/coroutine-sigaltstack.c
>> @@ -155,7 +155,7 @@ Coroutine *qemu_coroutine_new(void)
>>      stack_t oss;
>>      sigset_t sigs;
>>      sigset_t osigs;
>> -    jmp_buf old_env;
>> +    sigjmp_buf old_env;
>>
>>      /* The way to manipulate stack is with the sigaltstack function. We
>>       * prepare a stack, with it delivering a signal to ourselves and then
>
> Reviewed-by: Peter Maydell <address@hidden>
>
> I think I must have missed this one when I converted all the jmp_buf
> to sigjmp_buf in commit 6ab7e546.

Useful bit of information, perhaps you can amend the commit message with
it on commit.