signals/sigaltstack: Report current flag bits in sigaltstack()

[cascardo/linux.git] / kernel / signal.c

diff --git a/kernel/signal.c b/kernel/signal.c
index aa9bf00..ab122a2 100644 (file)
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -3099,12 +3099,14 @@ do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long s
 
        oss.ss_sp = (void __user *) current->sas_ss_sp;
        oss.ss_size = current->sas_ss_size;
-       oss.ss_flags = sas_ss_flags(sp);
+       oss.ss_flags = sas_ss_flags(sp) |
+               (current->sas_ss_flags & SS_FLAG_BITS);
 
        if (uss) {
                void __user *ss_sp;
                size_t ss_size;
-               int ss_flags;
+               unsigned ss_flags;
+               int ss_mode;
 
                error = -EFAULT;
                if (!access_ok(VERIFY_READ, uss, sizeof(*uss)))
@@ -3119,18 +3121,13 @@ do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long s
                if (on_sig_stack(sp))
                        goto out;
 
+               ss_mode = ss_flags & ~SS_FLAG_BITS;
                error = -EINVAL;
-               /*
-                * Note - this code used to test ss_flags incorrectly:
-                *        old code may have been written using ss_flags==0
-                *        to mean ss_flags==SS_ONSTACK (as this was the only
-                *        way that worked) - this fix preserves that older
-                *        mechanism.
-                */
-               if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
+               if (ss_mode != SS_DISABLE && ss_mode != SS_ONSTACK &&
+                               ss_mode != 0)
                        goto out;
 
-               if (ss_flags == SS_DISABLE) {
+               if (ss_mode == SS_DISABLE) {
                        ss_size = 0;
                        ss_sp = NULL;
                } else {
@@ -3141,6 +3138,7 @@ do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long s
 
                current->sas_ss_sp = (unsigned long) ss_sp;
                current->sas_ss_size = ss_size;
+               current->sas_ss_flags = ss_flags;
        }
 
        error = 0;
@@ -3171,9 +3169,14 @@ int restore_altstack(const stack_t __user *uss)
 int __save_altstack(stack_t __user *uss, unsigned long sp)
 {
        struct task_struct *t = current;
-       return  __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
-               __put_user(sas_ss_flags(sp), &uss->ss_flags) |
+       int err = __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
+               __put_user(t->sas_ss_flags, &uss->ss_flags) |
                __put_user(t->sas_ss_size, &uss->ss_size);
+       if (err)
+               return err;
+       if (t->sas_ss_flags & SS_AUTODISARM)
+               sas_ss_reset(t);
+       return 0;
 }
 
 #ifdef CONFIG_COMPAT