x86/entry: Consolidate check_user_regs()

The user register sanity check is sprinkled all over the place. Move it
into enter_from_user_mode().

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lkml.kernel.org/r/20200722220519.943016204@linutronix.de

diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
index 4eae4c1f254de7db4d3f961aa59d0aece9993103..ab6cb8602c0b9c1161e865bd43611daad63f3cbd 100644 (file)
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -82,10 +82,11 @@ static noinstr void check_user_regs(struct pt_regs *regs)
  * 2) Invoke context tracking if enabled to reactivate RCU
  * 3) Trace interrupts off state
  */
-static noinstr void enter_from_user_mode(void)
+static noinstr void enter_from_user_mode(struct pt_regs *regs)
 {
        enum ctx_state state = ct_state();
 
+       check_user_regs(regs);
        lockdep_hardirqs_off(CALLER_ADDR0);
        user_exit_irqoff();
 
@@ -95,8 +96,9 @@ static noinstr void enter_from_user_mode(void)
        instrumentation_end();
 }
 #else
-static __always_inline void enter_from_user_mode(void)
+static __always_inline void enter_from_user_mode(struct pt_regs *regs)
 {
+       check_user_regs(regs);
        lockdep_hardirqs_off(CALLER_ADDR0);
        instrumentation_begin();
        trace_hardirqs_off_finish();
@@ -369,9 +371,7 @@ __visible noinstr void do_syscall_64(unsigned long nr, struct pt_regs *regs)
 {
        struct thread_info *ti;
 
-       check_user_regs(regs);
-
-       enter_from_user_mode();
+       enter_from_user_mode(regs);
        instrumentation_begin();
 
        local_irq_enable();
@@ -434,9 +434,7 @@ static void do_syscall_32_irqs_on(struct pt_regs *regs)
 /* Handles int $0x80 */
 __visible noinstr void do_int80_syscall_32(struct pt_regs *regs)
 {
-       check_user_regs(regs);
-
-       enter_from_user_mode();
+       enter_from_user_mode(regs);
        instrumentation_begin();
 
        local_irq_enable();
@@ -487,8 +485,6 @@ __visible noinstr long do_fast_syscall_32(struct pt_regs *regs)
                                        vdso_image_32.sym_int80_landing_pad;
        bool success;
 
-       check_user_regs(regs);
-
        /*
         * SYSENTER loses EIP, and even SYSCALL32 needs us to skip forward
         * so that 'regs->ip -= 2' lands back on an int $0x80 instruction.
@@ -496,7 +492,7 @@ __visible noinstr long do_fast_syscall_32(struct pt_regs *regs)
         */
        regs->ip = landing_pad;
 
-       enter_from_user_mode();
+       enter_from_user_mode(regs);
        instrumentation_begin();
 
        local_irq_enable();
@@ -599,8 +595,7 @@ idtentry_state_t noinstr idtentry_enter(struct pt_regs *regs)
        };
 
        if (user_mode(regs)) {
-               check_user_regs(regs);
-               enter_from_user_mode();
+               enter_from_user_mode(regs);
                return ret;
        }
 
@@ -733,8 +728,7 @@ void noinstr idtentry_exit(struct pt_regs *regs, idtentry_state_t state)
  */
 void noinstr idtentry_enter_user(struct pt_regs *regs)
 {
-       check_user_regs(regs);
-       enter_from_user_mode();
+       enter_from_user_mode(regs);
 }
 
 /**