Re: [PATCH] linux-user: fix pidfd_send_signal()

[Helge Deller]

On 10/5/22 18:38, Laurent Vivier wrote:

According to pidfd_send_signal(2), info argument can be a NULL pointer.
Fix strace to correctly manage ending comma in parameters.

Fixes: cc054c6f13 ("linux-user: Add pidfd_open(), pidfd_send_signal() and 
pidfd_getfd() syscalls")
cc: Helge Deller <del...@gmx.de>
Signed-off-by: Laurent Vivier <laur...@vivier.eu>

Reviewed-by: Helge Deller <del...@gmx.de>

---
  linux-user/strace.c  |  4 ++--
  linux-user/syscall.c | 19 ++++++++++++-------
  2 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/linux-user/strace.c b/linux-user/strace.c
index 37bc96df9bb6..86c081c83f74 100644
--- a/linux-user/strace.c
+++ b/linux-user/strace.c
@@ -3383,10 +3383,10 @@ print_pidfd_send_signal(CPUArchState *cpu_env, const 
struct syscallname *name,

          unlock_user(p, arg2, 0);
      } else {
-        print_pointer(arg2, 1);
+        print_pointer(arg2, 0);
      }

-    print_raw_param("%u", arg3, 0);
+    print_raw_param("%u", arg3, 1);
      print_syscall_epilogue(name);
  }
  #endif
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 2e954d8dbd9e..b1493917ee07 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -8679,16 +8679,21 @@ static abi_long do_syscall1(CPUArchState *cpu_env, int 
num, abi_long arg1,
  #if defined(__NR_pidfd_send_signal) && defined(TARGET_NR_pidfd_send_signal)
      case TARGET_NR_pidfd_send_signal:
          {
-            siginfo_t uinfo;
+            siginfo_t uinfo, *puinfo;

-            p = lock_user(VERIFY_READ, arg3, sizeof(target_siginfo_t), 1);
-            if (!p) {
-                return -TARGET_EFAULT;
+            if (arg3) {
+                p = lock_user(VERIFY_READ, arg3, sizeof(target_siginfo_t), 1);
+                if (!p) {
+                    return -TARGET_EFAULT;
+                 }
+                 target_to_host_siginfo(&uinfo, p);
+                 unlock_user(p, arg3, 0);
+                 puinfo = &uinfo;
+            } else {
+                 puinfo = NULL;
              }
-            target_to_host_siginfo(&uinfo, p);
-            unlock_user(p, arg3, 0);
              ret = get_errno(pidfd_send_signal(arg1, 
target_to_host_signal(arg2),
-                &uinfo, arg4));
+                                              puinfo, arg4));
          }
          return ret;
  #endif