signal/ptrace: Add force_sig_ptrace_errno_trap and use it where needed

There are so many places that build struct siginfo by hand that at
least one of them is bound to get it wrong.  A handful of cases in the
kernel arguably did just that when using the errno field of siginfo to
pass no errno values to userspace.  The usage is limited to a single
si_code so at least does not mess up anything else.

Encapsulate this questionable pattern in a helper function so
that the userspace ABI is preserved.

Update all of the places that use this pattern to use the new helper
function.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

1 files changed, 15 insertions, 0 deletions

diff --git a/kernel/signal.c b/kernel/signal.c
index 4f6300ef8062..e549174c0831 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1599,6 +1599,21 @@ int force_sig_pkuerr(void __user *addr, u32 pkey)
 }
 #endif
 
+/* For the crazy architectures that include trap information in
+ * the errno field, instead of an actual errno value.
+ */
+int force_sig_ptrace_errno_trap(int errno, void __user *addr)
+{
+	struct siginfo info;
+
+	clear_siginfo(&info);
+	info.si_signo = SIGTRAP;
+	info.si_errno = errno;
+	info.si_code  = TRAP_HWBKPT;
+	info.si_addr  = addr;
+	return force_sig_info(info.si_signo, &info, current);
+}
+
 int kill_pgrp(struct pid *pid, int sig, int priv)
 {
 	int ret;