[PATCH 4.14 36/52] fcntl: dont cap l_start and l_end values for F_GETLK64 in compat syscall

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jeff Layton <jlayton@redhat.com>

commit 4d2dc2cc766c3b51929658cacbc6e34fc8e242fb upstream.

Currently, we're capping the values too low in the F_GETLK64 case. The
fields in that structure are 64-bit values, so we shouldn't need to do
any sort of fixup there.

Make sure we check that assumption at build time in the future however
by ensuring that the sizes we're copying will fit.

With this, we no longer need COMPAT_LOFF_T_MAX either, so remove it.

Fixes: 94073ad77fff2 (fs/locks: don't mess with the address limit in compat_fcntl64)
Reported-by: Vitaly Lipatov <lav@etersoft.ru>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Reviewed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/arm64/include/asm/compat.h   |    1 -
 arch/mips/include/asm/compat.h    |    1 -
 arch/parisc/include/asm/compat.h  |    1 -
 arch/powerpc/include/asm/compat.h |    1 -
 arch/s390/include/asm/compat.h    |    1 -
 arch/sparc/include/asm/compat.h   |    1 -
 arch/tile/include/asm/compat.h    |    1 -
 arch/x86/include/asm/compat.h     |    1 -
 fs/fcntl.c                        |   11 +++++------
 9 files changed, 5 insertions(+), 14 deletions(-)

--- a/arch/arm64/include/asm/compat.h
+++ b/arch/arm64/include/asm/compat.h
@@ -215,7 +215,6 @@ typedef struct compat_siginfo {
 } compat_siginfo_t;
 
 #define COMPAT_OFF_T_MAX	0x7fffffff
-#define COMPAT_LOFF_T_MAX	0x7fffffffffffffffL
 
 /*
  * A pointer passed in from user mode. This should not
--- a/arch/mips/include/asm/compat.h
+++ b/arch/mips/include/asm/compat.h
@@ -200,7 +200,6 @@ typedef struct compat_siginfo {
 } compat_siginfo_t;
 
 #define COMPAT_OFF_T_MAX	0x7fffffff
-#define COMPAT_LOFF_T_MAX	0x7fffffffffffffffL
 
 /*
  * A pointer passed in from user mode. This should not
--- a/arch/parisc/include/asm/compat.h
+++ b/arch/parisc/include/asm/compat.h
@@ -195,7 +195,6 @@ typedef struct compat_siginfo {
 } compat_siginfo_t;
 
 #define COMPAT_OFF_T_MAX	0x7fffffff
-#define COMPAT_LOFF_T_MAX	0x7fffffffffffffffL
 
 struct compat_ipc64_perm {
 	compat_key_t key;
--- a/arch/powerpc/include/asm/compat.h
+++ b/arch/powerpc/include/asm/compat.h
@@ -185,7 +185,6 @@ typedef struct compat_siginfo {
 } compat_siginfo_t;
 
 #define COMPAT_OFF_T_MAX	0x7fffffff
-#define COMPAT_LOFF_T_MAX	0x7fffffffffffffffL
 
 /*
  * A pointer passed in from user mode. This should not
--- a/arch/s390/include/asm/compat.h
+++ b/arch/s390/include/asm/compat.h
@@ -263,7 +263,6 @@ typedef struct compat_siginfo {
 #define si_overrun	_sifields._timer._overrun
 
 #define COMPAT_OFF_T_MAX	0x7fffffff
-#define COMPAT_LOFF_T_MAX	0x7fffffffffffffffL
 
 /*
  * A pointer passed in from user mode. This should not
--- a/arch/sparc/include/asm/compat.h
+++ b/arch/sparc/include/asm/compat.h
@@ -209,7 +209,6 @@ typedef struct compat_siginfo {
 } compat_siginfo_t;
 
 #define COMPAT_OFF_T_MAX	0x7fffffff
-#define COMPAT_LOFF_T_MAX	0x7fffffffffffffffL
 
 /*
  * A pointer passed in from user mode. This should not
--- a/arch/tile/include/asm/compat.h
+++ b/arch/tile/include/asm/compat.h
@@ -173,7 +173,6 @@ typedef struct compat_siginfo {
 } compat_siginfo_t;
 
 #define COMPAT_OFF_T_MAX	0x7fffffff
-#define COMPAT_LOFF_T_MAX	0x7fffffffffffffffL
 
 struct compat_ipc64_perm {
 	compat_key_t key;
--- a/arch/x86/include/asm/compat.h
+++ b/arch/x86/include/asm/compat.h
@@ -209,7 +209,6 @@ typedef struct compat_siginfo {
 } compat_siginfo_t;
 
 #define COMPAT_OFF_T_MAX	0x7fffffff
-#define COMPAT_LOFF_T_MAX	0x7fffffffffffffffL
 
 struct compat_ipc64_perm {
 	compat_key_t key;
--- a/fs/fcntl.c
+++ b/fs/fcntl.c
@@ -563,6 +563,9 @@ static int put_compat_flock64(const stru
 {
 	struct compat_flock64 fl;
 
+	BUILD_BUG_ON(sizeof(kfl->l_start) > sizeof(ufl->l_start));
+	BUILD_BUG_ON(sizeof(kfl->l_len) > sizeof(ufl->l_len));
+
 	memset(&fl, 0, sizeof(struct compat_flock64));
 	copy_flock_fields(&fl, kfl);
 	if (copy_to_user(ufl, &fl, sizeof(struct compat_flock64)))
@@ -641,12 +644,8 @@ COMPAT_SYSCALL_DEFINE3(fcntl64, unsigned
 		if (err)
 			break;
 		err = fcntl_getlk(f.file, convert_fcntl_cmd(cmd), &flock);
-		if (err)
-			break;
-		err = fixup_compat_flock(&flock);
-		if (err)
-			return err;
-		err = put_compat_flock64(&flock, compat_ptr(arg));
+		if (!err)
+			err = put_compat_flock64(&flock, compat_ptr(arg));
 		break;
 	case F_SETLK:
 	case F_SETLKW: