---

yaml
---
r: 16952
b: refs/heads/master
c: 2520f14
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 4a30131e7dbb17e5fec6958bfac9da9aff1fa29b
+refs/heads/master: 2520f14ca85e38f575eed6acc6e586df246abea6

trunk/fs/compat.c

@@ -494,9 +494,21 @@ asmlinkage long compat_sys_fcntl64(unsigned int fd, unsigned int cmd,
 		ret = sys_fcntl(fd, cmd, (unsigned long)&f);
 		set_fs(old_fs);
 		if (cmd == F_GETLK && ret == 0) {
-			if ((f.l_start >= COMPAT_OFF_T_MAX) ||
-			    ((f.l_start + f.l_len) > COMPAT_OFF_T_MAX))
+			/* GETLK was successfule and we need to return the data...
+			 * but it needs to fit in the compat structure.
+			 * l_start shouldn't be too big, unless the original
+			 * start + end is greater than COMPAT_OFF_T_MAX, in which
+			 * case the app was asking for trouble, so we return
+			 * -EOVERFLOW in that case.
+			 * l_len could be too big, in which case we just truncate it,
+			 * and only allow the app to see that part of the conflicting
+			 * lock that might make sense to it anyway
+			 */
+
+			if (f.l_start > COMPAT_OFF_T_MAX)
 				ret = -EOVERFLOW;
+			if (f.l_len > COMPAT_OFF_T_MAX)
+				f.l_len = COMPAT_OFF_T_MAX;
 			if (ret == 0)
 				ret = put_compat_flock(&f, compat_ptr(arg));
 		}
@@ -515,9 +527,11 @@ asmlinkage long compat_sys_fcntl64(unsigned int fd, unsigned int cmd,
 				(unsigned long)&f);
 		set_fs(old_fs);
 		if (cmd == F_GETLK64 && ret == 0) {
-			if ((f.l_start >= COMPAT_LOFF_T_MAX) ||
-			    ((f.l_start + f.l_len) > COMPAT_LOFF_T_MAX))
+			/* need to return lock information - see above for commentary */
+			if (f.l_start > COMPAT_LOFF_T_MAX)
 				ret = -EOVERFLOW;
+			if (f.l_len > COMPAT_LOFF_T_MAX)
+				f.l_len = COMPAT_LOFF_T_MAX;
 			if (ret == 0)
 				ret = put_compat_flock64(&f, compat_ptr(arg));
 		}