generic compat_sys_ustat

Due to a different size of ino_t ustat needs a compat handler, but
currently only x86 and mips provide one.  Add a generic compat_sys_ustat
and switch all architectures over to it.  Instead of doing various
user copy hacks compat_sys_ustat just reimplements sys_ustat as
it's trivial.  This was suggested by Arnd Bergmann.

Found by Eric Sandeen when running xfstests/017 on ppc64, which causes
stack smashing warnings on RHEL/Fedora due to the too large amount of
data writen by the syscall.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

3 files changed, 2 insertions, 36 deletions

diff --git a/arch/mips/kernel/linux32.c b/arch/mips/kernel/linux32.c
index 1a86f84fa947..784859cedef7 100644
--- a/arch/mips/kernel/linux32.c
+++ b/arch/mips/kernel/linux32.c
@@ -356,40 +356,6 @@ SYSCALL_DEFINE1(32_personality, unsigned long, personality)
         return ret;
 }
 
-/* ustat compatibility */
-struct ustat32 {
-        compat_daddr_t  f_tfree;
-        compat_ino_t    f_tinode;
-        char            f_fname[6];
-        char            f_fpack[6];
-};
-
-extern asmlinkage long sys_ustat(dev_t dev, struct ustat __user * ubuf);
-
-SYSCALL_DEFINE2(32_ustat, dev_t, dev, struct ustat32 __user *, ubuf32)
-{
-        int err;
-        struct ustat tmp;
-        struct ustat32 tmp32;
-        mm_segment_t old_fs = get_fs();
-
-        set_fs(KERNEL_DS);
-        err = sys_ustat(dev, (struct ustat __user *)&tmp);
-        set_fs(old_fs);
-
-        if (err)
-                goto out;
-
-        memset(&tmp32, 0, sizeof(struct ustat32));
-        tmp32.f_tfree = tmp.f_tfree;
-        tmp32.f_tinode = tmp.f_tinode;
-
-        err = copy_to_user(ubuf32, &tmp32, sizeof(struct ustat32)) ? -EFAULT : 0;
-
-out:
-        return err;
-}
-
 SYSCALL_DEFINE4(32_sendfile, long, out_fd, long, in_fd,
         compat_off_t __user *, offset, s32, count)
 {
diff --git a/arch/mips/kernel/scall64-n32.S b/arch/mips/kernel/scall64-n32.S
index 7438e92f8a01..f61d6b0e5731 100644
--- a/arch/mips/kernel/scall64-n32.S
+++ b/arch/mips/kernel/scall64-n32.S
@@ -253,7 +253,7 @@ EXPORT(sysn32_call_table)
         PTR     compat_sys_utime                /* 6130 */
         PTR     sys_mknod
         PTR     sys_32_personality
-        PTR     sys_32_ustat
+        PTR     compat_sys_ustat
         PTR     compat_sys_statfs
         PTR     compat_sys_fstatfs              /* 6135 */
         PTR     sys_sysfs
diff --git a/arch/mips/kernel/scall64-o32.S b/arch/mips/kernel/scall64-o32.S
index b0fef4ff9827..60997f1f69d4 100644
--- a/arch/mips/kernel/scall64-o32.S
+++ b/arch/mips/kernel/scall64-o32.S
@@ -265,7 +265,7 @@ sys_call_table:
         PTR     sys_olduname
         PTR     sys_umask                       /* 4060 */
         PTR     sys_chroot
-        PTR     sys_32_ustat
+        PTR     compat_sys_ustat
         PTR     sys_dup2
         PTR     sys_getppid
         PTR     sys_getpgrp                     /* 4065 */