[PATCH] arc4random: fix getrandom fallback to /dev/urandom

[Anthony Iliopoulos <ailiop@suse.com>]

arc4random_buf relies on the errno of getrandom_nocancel to fallback to
/dev/urandom, but getrandom_nocancel returns a status code instead of
the syscall errno (-ENOSYS) so it breaks the expectation and thus the
fallback in cases where a kernel does not support the getrandom syscall.

Commit 609c9d0951da ("malloc: Do not clobber errno on __getrandom_nocancel
(BZ #29624)") changed __getrandom_nocancel from INLINE_SYSCALL_CALL to
INTERNAL_SYSCALL_CALL and modified arc4random_buf to rely on the return
status instead of errno.

Commit 5a85786a9005 ("Make __getrandom_nocancel set errno and add a
_nostatus version") changed __getrandom_nocancel back to
INLINE_SYSCALL_CALL and added a __getrandom_nocancel_nostatus variant
that calls via INTERNAL_SYSCALL_CALL, but this broke the fallback of
arc4random on kernels where the getrandom syscall is not available.

Fix it by calling __getrandom_nocancel_nostatus from arc4random_buf so
that the fallback works again.

Signed-off-by: Anthony Iliopoulos <ailiop@suse.com>
Fixes: 5a85786a9005 ("Make __getrandom_nocancel set errno and add a _nostatus version")
---
 stdlib/arc4random.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/stdlib/arc4random.c b/stdlib/arc4random.c
index 3ae8fc130234..9b6a6ee85150 100644
--- a/stdlib/arc4random.c
+++ b/stdlib/arc4random.c
@@ -42,7 +42,7 @@ __arc4random_buf (void *p, size_t n)
 
   for (;;)
     {
-      l = TEMP_FAILURE_RETRY (__getrandom_nocancel (p, n, 0));
+      l = TEMP_FAILURE_RETRY (__getrandom_nocancel_nostatus (p, n, 0));
       if (l > 0)
 	{
 	  if ((size_t) l == n)
-- 
2.44.0