[PATCH v2] Fix stack smashing when handling PR_GET_PDEATHSIG

[Stephen Long]

The bug was triggered by the following code on aarch64-linux-user:

#include <signal.h>
#include <sys/prctl.h>

int main(void)
{
  int PDeathSig = 0;
  if (prctl(PR_GET_PDEATHSIG, &PDeathSig) == 0 && PDeathSig == SIGKILL)
    prctl(PR_GET_PDEATHSIG, 0);
  return (PDeathSig == SIGKILL);
}

Signed-off-by: Stephen Long <address@hidden>
Signed-off-by: Ana Pazos <address@hidden>
---

I fixed the incorrect subject line. PR_GETDEATHSIG should be PR_GET_PDEATHSIG.
Is there a test folder where I can include the code that triggered the bug?
Also, I thought "int" can be 2 bytes on some machines.

 linux-user/syscall.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 05f03919ff..91f91147ba 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -10256,7 +10256,7 @@ static abi_long do_syscall1(void *cpu_env, int num, 
abi_long arg1,
             int deathsig;
             ret = get_errno(prctl(arg1, &deathsig, arg3, arg4, arg5));
             if (!is_error(ret) && arg2
-                && put_user_ual(deathsig, arg2)) {
+                && put_user_s32(deathsig, arg2)) {
                 return -TARGET_EFAULT;
             }
             return ret;
-- 
2.17.1