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>

2 files changed, 1 insertions, 23 deletions

diff --git a/arch/x86/ia32/ia32entry.S b/arch/x86/ia32/ia32entry.S
index 5a0d76dc56a..8ef8876666b 100644
--- a/arch/x86/ia32/ia32entry.S
+++ b/arch/x86/ia32/ia32entry.S
@@ -557,7 +557,7 @@ ia32_sys_call_table:
         .quad sys32_olduname
         .quad sys_umask         /* 60 */
         .quad sys_chroot
-        .quad sys32_ustat
+        .quad compat_sys_ustat
         .quad sys_dup2
         .quad sys_getppid
         .quad sys_getpgrp               /* 65 */
diff --git a/arch/x86/ia32/sys_ia32.c b/arch/x86/ia32/sys_ia32.c
index 6c0d7f6231a..efac92fd1ef 100644
--- a/arch/x86/ia32/sys_ia32.c
+++ b/arch/x86/ia32/sys_ia32.c
@@ -638,28 +638,6 @@ long sys32_uname(struct old_utsname __user *name)
         return err ? -EFAULT : 0;
 }
 
-long sys32_ustat(unsigned dev, struct ustat32 __user *u32p)
-{
-        struct ustat u;
-        mm_segment_t seg;
-        int ret;
-
-        seg = get_fs();
-        set_fs(KERNEL_DS);
-        ret = sys_ustat(dev, (struct ustat __user *)&u);
-        set_fs(seg);
-        if (ret < 0)
-                return ret;
-
-        if (!access_ok(VERIFY_WRITE, u32p, sizeof(struct ustat32)) ||
-            __put_user((__u32) u.f_tfree, &u32p->f_tfree) ||
-            __put_user((__u32) u.f_tinode, &u32p->f_tfree) ||
-            __copy_to_user(&u32p->f_fname, u.f_fname, sizeof(u.f_fname)) ||
-            __copy_to_user(&u32p->f_fpack, u.f_fpack, sizeof(u.f_fpack)))
-                ret = -EFAULT;
-        return ret;
-}
-
 asmlinkage long sys32_execve(char __user *name, compat_uptr_t __user *argv,
                              compat_uptr_t __user *envp, struct pt_regs *regs)
 {