linux-kernel - [RFC PATCH 12/35] syscalls: do not call sys_rt

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Message-Id: <20180311105557.20807-13-linux@dominikbrodowski.net>
Date:   Sun, 11 Mar 2018 11:55:34 +0100
From:   Dominik Brodowski <linux@...inikbrodowski.net>
To:     linux-kernel@...r.kernel.org, luto@...nel.org,
        torvalds@...ux-foundation.org, mingo@...nel.org,
        viro@...iv.linux.org.uk, akpm@...ux-foundation.org
Subject: [RFC PATCH 12/35] syscalls: do not call sys_rt_sigpending() within the kernel

A similar code path is already open-coded three times (in sys_rt_sigpending
and in the two compat stubs), so do it a fourth time here.

CC: Al Viro <viro@...iv.linux.org.uk>
CC: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Dominik Brodowski <linux@...inikbrodowski.net>
---
 include/linux/syscalls.h |  2 +-
 kernel/signal.c          | 13 +++++++++++--
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 700a83a9c1ad..79c46c46603b 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -288,7 +288,7 @@ asmlinkage long sys_capset(cap_user_header_t header,
 				const cap_user_data_t data);
 asmlinkage long sys_personality(unsigned int personality);
 
-asmlinkage long sys_sigpending(old_sigset_t __user *set);
+asmlinkage long sys_sigpending(old_sigset_t __user *uset);
 asmlinkage long sys_sigprocmask(int how, old_sigset_t __user *set,
 				old_sigset_t __user *oset);
 asmlinkage long sys_sigaltstack(const struct sigaltstack __user *uss,
diff --git a/kernel/signal.c b/kernel/signal.c
index c6e4c83dc090..fe0906d1d3cc 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -3631,9 +3631,18 @@ int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp)
  *  sys_sigpending - examine pending signals
  *  @set: where mask of pending signal is returned
  */
-SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set)
+SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, uset)
 {
-	return sys_rt_sigpending((sigset_t __user *)set, sizeof(old_sigset_t)); 
+	sigset_t set;
+	int err;
+
+	if (sizeof(old_sigset_t) > sizeof(*uset))
+		return -EINVAL;
+
+	err = do_sigpending(&set);
+	if (!err && copy_to_user(uset, &set, sizeof(old_sigset_t)))
+		err = -EFAULT;
+	return err;
 }
 
 #ifdef CONFIG_COMPAT
-- 
2.16.2