[PATCH] linux-user/syscall: Do not ignore info.si_pid == 0 in waitid()

[Serge Belyshev]

When called with WNOHANG and no child has exited, waitid returns with
info.si_pid set to zero and thus check for info.si_pid != 0 will cause
target siginfo structure to be uninitialized.  Fixed by removing the check.

Signed-off-by: Serge Belyshev <belyshev@depni.sinp.msu.ru>
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/817
---
 linux-user/syscall.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 5950222a77..b80531ac4c 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -8724,9 +8724,8 @@ static abi_long do_syscall1(void *cpu_env, int num, 
abi_long arg1,
     case TARGET_NR_waitid:
         {
             siginfo_t info;
-            info.si_pid = 0;
             ret = get_errno(safe_waitid(arg1, arg2, &info, arg4, NULL));
-            if (!is_error(ret) && arg3 && info.si_pid != 0) {
+            if (!is_error(ret) && arg3) {
                 if (!(p = lock_user(VERIFY_WRITE, arg3, 
sizeof(target_siginfo_t), 0)))
                     return -TARGET_EFAULT;
                 host_to_target_siginfo(p, &info);
-- 
2.34.1