Re: [igt-dev] [PATCH i-g-t] lib/tests/igt_fork.c: Fix error in mmap() flags

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Fri, Oct 07, 2022 at 09:52:41AM -0500, Jake Freeland wrote:
> In subtest_leak(), mmap() is called with the flag PROT_WRITE,
> but no PROT_READ. Later in the function, the mapped memory is
> read using `children[i]`. In FreeBSD, the lack of PROT_READ
> causes SIGSEGV. Adding the PROT_READ flag to the mmap() call
> fixes this.

Isn't it a CPU architecture thing rather than an OS thing?
Well, I guess it could be both in some cases.

> 
> Signed-off-by: Jake Freeland <jfree@freebsd.org>
> ---
>  lib/tests/igt_fork.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/lib/tests/igt_fork.c b/lib/tests/igt_fork.c
> index d19d0945..d883aba4 100644
> --- a/lib/tests/igt_fork.c
> +++ b/lib/tests/igt_fork.c
> @@ -109,7 +109,7 @@ __noreturn static void igt_fork_timeout_leak(void)
>  __noreturn static void subtest_leak(void)
>  {
>  	pid_t *children =
> -		mmap(0, 4096, PROT_WRITE, MAP_SHARED | MAP_ANON, -1, 0);
> +		mmap(0, 4096, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANON, -1, 0);
>  	const int num_children = 4096 / sizeof(*children);
>  
>  	igt_subtest_init(fake_argc, fake_argv);
> -- 
> 2.37.0 (Apple Git-136)

-- 
Ville Syrjälä
Intel