vfs: canonicalize create mode in build_open_flags()

Userspace can pass weird create mode in open(2) that we canonicalize to "(mode & S_IALLUGO) | S_IFREG" in vfs_create(). The problem is that we use the uncanonicalized mode before calling vfs_create() with unforseen consequences. So do the canonicalization early in build_open_flags(). Signed-off-by: Miklos Szeredi <[email protected]> Tested-by: Richard W.M. Jones <[email protected]> CC: [email protected]
laijs · Aug 15, 2012 · e68726f · e68726f
1 parent ddf343f
commit e68726f
Showing 1 changed file with 4 additions and 3 deletions.
diff --git a/fs/open.c b/fs/open.c
@@ -852,9 +852,10 @@ static inline int build_open_flags(int flags, umode_t mode, struct open_flags *o
 	int lookup_flags = 0;
 	int acc_mode;
 
-	if (!(flags & O_CREAT))
-		mode = 0;
-	op->mode = mode;
+	if (flags & O_CREAT)
+		op->mode = (mode & S_IALLUGO) | S_IFREG;
+	else
+		op->mode = 0;
 
 	/* Must never be set by userspace */
 	flags &= ~FMODE_NONOTIFY;