um: Handle tracehook_report_syscall_entry() result

tracehook_report_syscall_entry() is allowed to fail,
in case of failure we have to abort the current syscall.

Signed-off-by: Richard Weinberger <richard@nod.at>

2 files changed, 8 insertions, 4 deletions

diff --git a/arch/um/kernel/ptrace.c b/arch/um/kernel/ptrace.c
index 174ee5017264..cac2ea058b7a 100644
--- a/arch/um/kernel/ptrace.c
+++ b/arch/um/kernel/ptrace.c
@@ -131,7 +131,7 @@ static void send_sigtrap(struct task_struct *tsk, struct uml_pt_regs *regs,
  * XXX Check PT_DTRACE vs TIF_SINGLESTEP for singlestepping check and
  * PT_PTRACED vs TIF_SYSCALL_TRACE for syscall tracing check
  */
-void syscall_trace_enter(struct pt_regs *regs)
+int syscall_trace_enter(struct pt_regs *regs)
 {
         audit_syscall_entry(UPT_SYSCALL_NR(&regs->regs),
                             UPT_SYSCALL_ARG1(&regs->regs),
@@ -140,9 +140,9 @@ void syscall_trace_enter(struct pt_regs *regs)
                             UPT_SYSCALL_ARG4(&regs->regs));
 
         if (!test_thread_flag(TIF_SYSCALL_TRACE))
-                return;
+                return 0;
 
-        tracehook_report_syscall_entry(regs);
+        return tracehook_report_syscall_entry(regs);
 }
 
 void syscall_trace_leave(struct pt_regs *regs)
diff --git a/arch/um/kernel/skas/syscall.c b/arch/um/kernel/skas/syscall.c
index c0681e097432..d9ec0068b623 100644
--- a/arch/um/kernel/skas/syscall.c
+++ b/arch/um/kernel/skas/syscall.c
@@ -18,7 +18,10 @@ void handle_syscall(struct uml_pt_regs *r)
         long result;
         int syscall;
 
-        syscall_trace_enter(regs);
+        if (syscall_trace_enter(regs)) {
+                result = -ENOSYS;
+                goto out;
+        }
 
         /*
          * This should go in the declaration of syscall, but when I do that,
@@ -34,6 +37,7 @@ void handle_syscall(struct uml_pt_regs *r)
                 result = -ENOSYS;
         else result = EXECUTE_SYSCALL(syscall, regs);
 
+out:
         PT_REGS_SET_SYSCALL_RETURN(regs, result);
 
         syscall_trace_leave(regs);