[PATCH] stdlib: fix arc4random fallback to /dev/urandom (BZ 31612)

[Adhemerval Zanella Netto]

Ping, I really want this small fix on 2.40.

On 06/05/24 15:19, Adhemerval Zanella wrote:
> The __getrandom_nocancel used by __arc4random_buf uses
> INLINE_SYSCALL_CALL (which returns -1/errno) and the loop checks for
> the return value instead of errno to fallback to /dev/urandom.
> 
> The malloc code now uses __getrandom_nocancel_nostatus, which uses
> INTERNAL_SYSCALL_CALL, so there is no need to use the variant that does
> not set errno (BZ#29624).
> 
> Checked on x86_64-linux-gnu.
> ---
>  stdlib/arc4random.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/stdlib/arc4random.c b/stdlib/arc4random.c
> index 3ae8fc1302..7818cb9cf6 100644
> --- a/stdlib/arc4random.c
> +++ b/stdlib/arc4random.c
> @@ -51,7 +51,7 @@ __arc4random_buf (void *p, size_t n)
>  	  n -= l;
>  	  continue; /* Interrupted by a signal; keep going.  */
>  	}
> -      else if (l == -ENOSYS)
> +      else if (l < 0 && errno == ENOSYS)
>  	break; /* No syscall, so fallback to /dev/urandom.  */
>        arc4random_getrandom_failure ();
>      }