[PATCH] compat: sync compat_stats with statfs.

[PATCH] compat: sync compat_stats with statfs.

[Eric W. Biederman]

This was found by inspection while tracking a similar
bug in compat_statfs64, that has been fixed in mainline
since decemeber.

- This fixes a bug where not all of the f_spare fields
  were cleared on mips and s390.
- Add the f_flags field to struct compat_statfs
- Copy f_flags to userspace in case someone cares.
- Use __clear_user to copy the f_spare field to userspace
  to ensure that all of the elements of f_spare are cleared.
  On some architectures f_spare is has 5 ints and on some
  architectures f_spare only has 4 ints.  Which makes
  the previous technique of clearing each int individually
  broken.

I don't expect anyone actually uses the old statfs system
call anymore but if they do let them benefit from having
the compat and the native version working the same.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
---
 arch/mips/include/asm/compat.h    |    3 ++-
 arch/parisc/include/asm/compat.h  |    3 ++-
 arch/powerpc/include/asm/compat.h |    3 ++-
 arch/s390/include/asm/compat.h    |    3 ++-
 arch/sparc/include/asm/compat.h   |    3 ++-
 arch/x86/include/asm/compat.h     |    3 ++-
 fs/compat.c                       |    7 ++-----
 7 files changed, 14 insertions(+), 11 deletions(-)

diff --git a/arch/mips/include/asm/compat.h b/arch/mips/include/asm/compat.h
index dbc5106..b77df03 100644
--- a/arch/mips/include/asm/compat.h
+++ b/arch/mips/include/asm/compat.h
@@ -111,7 +111,8 @@ struct compat_statfs {
 	int		f_bavail;
 	compat_fsid_t	f_fsid;
 	int		f_namelen;
-	int		f_spare[6];
+	int		f_flags;
+	int		f_spare[5];
 };
 
 #define COMPAT_RLIM_INFINITY	0x7fffffffUL
diff --git a/arch/parisc/include/asm/compat.h b/arch/parisc/include/asm/compat.h
index efa0b60..760f331 100644
--- a/arch/parisc/include/asm/compat.h
+++ b/arch/parisc/include/asm/compat.h
@@ -105,7 +105,8 @@ struct compat_statfs {
 	__kernel_fsid_t	f_fsid;
 	s32		f_namelen;
 	s32		f_frsize;
-	s32		f_spare[5];
+	s32		f_flags;
+	s32		f_spare[4];
 };
 
 struct compat_sigcontext {
diff --git a/arch/powerpc/include/asm/compat.h b/arch/powerpc/include/asm/compat.h
index 91010e8..88e602f 100644
--- a/arch/powerpc/include/asm/compat.h
+++ b/arch/powerpc/include/asm/compat.h
@@ -100,7 +100,8 @@ struct compat_statfs {
 	compat_fsid_t	f_fsid;
 	int		f_namelen;	/* SunOS ignores this field. */
 	int		f_frsize;
-	int		f_spare[5];
+	int		f_flags;
+	int		f_spare[4];
 };
 
 #define COMPAT_RLIM_OLD_INFINITY	0x7fffffff
diff --git a/arch/s390/include/asm/compat.h b/arch/s390/include/asm/compat.h
index da359ca..cdb9b78 100644
--- a/arch/s390/include/asm/compat.h
+++ b/arch/s390/include/asm/compat.h
@@ -131,7 +131,8 @@ struct compat_statfs {
 	compat_fsid_t	f_fsid;
 	s32		f_namelen;
 	s32		f_frsize;
-	s32		f_spare[6];
+	s32		f_flags;
+	s32		f_spare[5];
 };
 
 #define COMPAT_RLIM_OLD_INFINITY	0x7fffffff
diff --git a/arch/sparc/include/asm/compat.h b/arch/sparc/include/asm/compat.h
index 6f57325..b8be20d 100644
--- a/arch/sparc/include/asm/compat.h
+++ b/arch/sparc/include/asm/compat.h
@@ -134,7 +134,8 @@ struct compat_statfs {
 	compat_fsid_t	f_fsid;
 	int		f_namelen;	/* SunOS ignores this field. */
 	int		f_frsize;
-	int		f_spare[5];
+	int		f_flags;
+	int		f_spare[4];
 };
 
 #define COMPAT_RLIM_INFINITY 0x7fffffff
diff --git a/arch/x86/include/asm/compat.h b/arch/x86/include/asm/compat.h
index 1d9cd27..30d737e 100644
--- a/arch/x86/include/asm/compat.h
+++ b/arch/x86/include/asm/compat.h
@@ -108,7 +108,8 @@ struct compat_statfs {
 	compat_fsid_t	f_fsid;
 	int		f_namelen;	/* SunOS ignores this field. */
 	int		f_frsize;
-	int		f_spare[5];
+	int		f_flags;
+	int		f_spare[4];
 };
 
 #define COMPAT_RLIM_OLD_INFINITY	0x7fffffff
diff --git a/fs/compat.c b/fs/compat.c
index 58b1da4..0f1ab46 100644
--- a/fs/compat.c
+++ b/fs/compat.c
@@ -247,11 +247,8 @@ static int put_compat_statfs(struct compat_statfs __user *ubuf, struct kstatfs *
 	    __put_user(kbuf->f_fsid.val[0], &ubuf->f_fsid.val[0]) ||
 	    __put_user(kbuf->f_fsid.val[1], &ubuf->f_fsid.val[1]) ||
 	    __put_user(kbuf->f_frsize, &ubuf->f_frsize) ||
-	    __put_user(0, &ubuf->f_spare[0]) || 
-	    __put_user(0, &ubuf->f_spare[1]) || 
-	    __put_user(0, &ubuf->f_spare[2]) || 
-	    __put_user(0, &ubuf->f_spare[3]) || 
-	    __put_user(0, &ubuf->f_spare[4]))
+	    __put_user(kbuf->f_flags, &ubuf->f_flags) ||
+	    __clear_user(ubuf->f_spare, sizeof(ubuf->f_spare)))
 		return -EFAULT;
 	return 0;
 }
-- 
1.7.2.5

Re: [PATCH] compat: sync compat_stats with statfs.

[Arnd Bergmann]

On Monday 17 October 2011 13:40:02 Eric W. Biederman wrote:
> This was found by inspection while tracking a similar
> bug in compat_statfs64, that has been fixed in mainline
> since decemeber.
> 
> - This fixes a bug where not all of the f_spare fields
>   were cleared on mips and s390.
> - Add the f_flags field to struct compat_statfs
> - Copy f_flags to userspace in case someone cares.
> - Use __clear_user to copy the f_spare field to userspace
>   to ensure that all of the elements of f_spare are cleared.
>   On some architectures f_spare is has 5 ints and on some
>   architectures f_spare only has 4 ints.  Which makes
>   the previous technique of clearing each int individually
>   broken.
> 
> I don't expect anyone actually uses the old statfs system
> call anymore but if they do let them benefit from having
> the compat and the native version working the same.
> 
> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

Looks good to me.

Acked-by: Arnd Bergmann <arnd@arndb.de>

Apparently, this could have been worse on tile, which has
#define compat_statfs statfs, so that the old
"__put_user(0, &ubuf->f_spare[4]))" was writing beyond the
end of struct statfs. Fortunately, this never gets called
on tile, which only provides compat_sys_statfs64 to user space,
not compat_sys_statfs.

	Arnd