signal: replace sigset_to_compat() with put_compat_sigset()

There are 4 callers of sigset_to_compat() in the entire kernel.  One is
in sparc compat rt_sigaction(2), the rest are in kernel/signal.c itself.
All are followed by copy_to_user(), and all but the sparc one are under
"if it's big-endian..." ifdefs.

Let's transform sigset_to_compat() into put_compat_sigset() that also
calls copy_to_user().

Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/arch/sparc/kernel/sys_sparc32.c b/arch/sparc/kernel/sys_sparc32.c
index bca44f3e6b86ca5e3c5def34c3db9ad2670e0898..5e2bec9e41b28fe9e9aa20f7027034cfd08659f4 100644 (file)
--- a/arch/sparc/kernel/sys_sparc32.c
+++ b/arch/sparc/kernel/sys_sparc32.c
@@ -159,7 +159,6 @@ COMPAT_SYSCALL_DEFINE5(rt_sigaction, int, sig,
 {
         struct k_sigaction new_ka, old_ka;
         int ret;
-       compat_sigset_t set32;
 
         /* XXX: Don't preclude handling different sized sigset_t's.  */
         if (sigsetsize != sizeof(compat_sigset_t))
@@ -167,6 +166,7 @@ COMPAT_SYSCALL_DEFINE5(rt_sigaction, int, sig,
 
         if (act) {
                u32 u_handler, u_restorer;
+               compat_sigset_t set32;
 
                new_ka.ka_restorer = restorer;
                ret = get_user(u_handler, &act->sa_handler);
@@ -183,9 +183,9 @@ COMPAT_SYSCALL_DEFINE5(rt_sigaction, int, sig,
        ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
 
        if (!ret && oact) {
-               sigset_to_compat(&set32, &old_ka.sa.sa_mask);
                ret = put_user(ptr_to_compat(old_ka.sa.sa_handler), &oact->sa_handler);
-               ret |= copy_to_user(&oact->sa_mask, &set32, sizeof(compat_sigset_t));
+               ret |= put_compat_sigset(&oact->sa_mask, &old_ka.sa.sa_mask,
+                                        sizeof(oact->sa_mask));
                ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags);
                ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer), &oact->sa_restorer);
                if (ret)

diff --git a/include/linux/compat.h b/include/linux/compat.h
index a5619de3437d9b1691b0e707bb2577b075592822..ab1baa79abe89b2c601faad2dd1552f723795db2 100644 (file)
--- a/include/linux/compat.h
+++ b/include/linux/compat.h
@@ -456,7 +456,8 @@ asmlinkage long compat_sys_settimeofday(struct compat_timeval __user *tv,
 asmlinkage long compat_sys_adjtimex(struct compat_timex __user *utp);
 
 extern void sigset_from_compat(sigset_t *set, const compat_sigset_t *compat);
-extern void sigset_to_compat(compat_sigset_t *compat, const sigset_t *set);
+extern int put_compat_sigset(compat_sigset_t __user *compat,
+                            const sigset_t *set, unsigned int size);
 
 asmlinkage long compat_sys_migrate_pages(compat_pid_t pid,
                compat_ulong_t maxnode, const compat_ulong_t __user *old_nodes,

diff --git a/kernel/compat.c b/kernel/compat.c
index 772e038d04d9a85ef6e78c2df8924ca5348fce78..18dd902c9052bc98228b3bd6f9f2cc27f2dff69b 100644 (file)
--- a/kernel/compat.c
+++ b/kernel/compat.c
@@ -497,15 +497,23 @@ sigset_from_compat(sigset_t *set, const compat_sigset_t *compat)
 }
 EXPORT_SYMBOL_GPL(sigset_from_compat);
 
-void
-sigset_to_compat(compat_sigset_t *compat, const sigset_t *set)
+int
+put_compat_sigset(compat_sigset_t __user *compat, const sigset_t *set,
+                 unsigned int size)
 {
+       /* size <= sizeof(compat_sigset_t) <= sizeof(sigset_t) */
+#ifdef __BIG_ENDIAN
+       compat_sigset_t v;
        switch (_NSIG_WORDS) {
-       case 4: compat->sig[7] = (set->sig[3] >> 32); compat->sig[6] = set->sig[3];
-       case 3: compat->sig[5] = (set->sig[2] >> 32); compat->sig[4] = set->sig[2];
-       case 2: compat->sig[3] = (set->sig[1] >> 32); compat->sig[2] = set->sig[1];
-       case 1: compat->sig[1] = (set->sig[0] >> 32); compat->sig[0] = set->sig[0];
+       case 4: v.sig[7] = (set->sig[3] >> 32); v.sig[6] = set->sig[3];
+       case 3: v.sig[5] = (set->sig[2] >> 32); v.sig[4] = set->sig[2];
+       case 2: v.sig[3] = (set->sig[1] >> 32); v.sig[2] = set->sig[1];
+       case 1: v.sig[1] = (set->sig[0] >> 32); v.sig[0] = set->sig[0];
        }
+       return copy_to_user(compat, &v, size) ? -EFAULT : 0;
+#else
+       return copy_to_user(compat, set, size) ? -EFAULT : 0;
+#endif
 }
 
 #ifdef CONFIG_NUMA

diff --git a/kernel/signal.c b/kernel/signal.c
index 800a18f77732c14cf49d81bc615b01cd56d11933..14ad6bb90dadbbd6e053dd247c96bbd848d25aef 100644 (file)
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -2621,13 +2621,7 @@ COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset,
                if (error)
                        return error;
        }
-       if (oset) {
-               compat_sigset_t old32;
-               sigset_to_compat(&old32, &old_set);
-               if (copy_to_user(oset, &old32, sizeof(compat_sigset_t)))
-                       return -EFAULT;
-       }
-       return 0;
+       return oset ? put_compat_sigset(oset, &old_set, sizeof(*oset)) : 0;
 #else
        return sys_rt_sigprocmask(how, (sigset_t __user *)nset,
                                  (sigset_t __user *)oset, sigsetsize);
@@ -2669,20 +2663,11 @@ SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize)
 COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset,
                compat_size_t, sigsetsize)
 {
-#ifdef __BIG_ENDIAN
        sigset_t set;
        int err = do_sigpending(&set, sigsetsize);
-       if (!err) {
-               compat_sigset_t set32;
-               sigset_to_compat(&set32, &set);
-               /* we can get here only if sigsetsize <= sizeof(set) */
-               if (copy_to_user(uset, &set32, sigsetsize))
-                       err = -EFAULT;
-       }
+       if (!err)
+               err = put_compat_sigset(uset, &set, sigsetsize);
        return err;
-#else
-       return sys_rt_sigpending((sigset_t __user *)uset, sigsetsize);
-#endif
 }
 #endif
 
@@ -3451,7 +3436,6 @@ COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig,
                compat_size_t, sigsetsize)
 {
        struct k_sigaction new_ka, old_ka;
-       compat_sigset_t mask;
 #ifdef __ARCH_HAS_SA_RESTORER
        compat_uptr_t restorer;
 #endif
@@ -3463,6 +3447,7 @@ COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig,
 
        if (act) {
                compat_uptr_t handler;
+               compat_sigset_t mask;
                ret = get_user(handler, &act->sa_handler);
                new_ka.sa.sa_handler = compat_ptr(handler);
 #ifdef __ARCH_HAS_SA_RESTORER
@@ -3478,10 +3463,10 @@ COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig,
 
        ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
        if (!ret && oact) {
-               sigset_to_compat(&mask, &old_ka.sa.sa_mask);
                ret = put_user(ptr_to_compat(old_ka.sa.sa_handler), 
                               &oact->sa_handler);
-               ret |= copy_to_user(&oact->sa_mask, &mask, sizeof(mask));
+               ret |= put_compat_sigset(&oact->sa_mask, &old_ka.sa.sa_mask,
+                                        sizeof(oact->sa_mask));
                ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags);
 #ifdef __ARCH_HAS_SA_RESTORER
                ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer),