1 files changed, 27 insertions, 17 deletions

diff --git a/fs/fat/file.c b/fs/fat/file.c
index 27cc1164ec36..771326b8047e 100644
--- a/fs/fat/file.c
+++ b/fs/fat/file.c
@@ -257,26 +257,34 @@ int fat_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
 }
 EXPORT_SYMBOL_GPL(fat_getattr);
 
-static int fat_check_mode(const struct msdos_sb_info *sbi, struct inode *inode,
-                          mode_t mode)
+static int fat_sanitize_mode(const struct msdos_sb_info *sbi,
+                             struct inode *inode, umode_t *mode_ptr)
 {
-        mode_t mask, req = mode & ~S_IFMT;
+        mode_t mask, perm;
 
-        if (S_ISREG(mode))
+        /*
+         * Note, the basic check is already done by a caller of
+         * (attr->ia_mode & ~MSDOS_VALID_MODE)
+         */
+
+        if (S_ISREG(inode->i_mode))
                 mask = sbi->options.fs_fmask;
         else
                 mask = sbi->options.fs_dmask;
 
+        perm = *mode_ptr & ~(S_IFMT | mask);
+
         /*
          * Of the r and x bits, all (subject to umask) must be present. Of the
          * w bits, either all (subject to umask) or none must be present.
          */
-        req &= ~mask;
-        if ((req & (S_IRUGO | S_IXUGO)) != (inode->i_mode & (S_IRUGO|S_IXUGO)))
+        if ((perm & (S_IRUGO | S_IXUGO)) != (inode->i_mode & (S_IRUGO|S_IXUGO)))
                 return -EPERM;
-        if ((req & S_IWUGO) && ((req & S_IWUGO) != (S_IWUGO & ~mask)))
+        if ((perm & S_IWUGO) && ((perm & S_IWUGO) != (S_IWUGO & ~mask)))
                 return -EPERM;
 
+        *mode_ptr &= S_IFMT | perm;
+
         return 0;
 }
 
@@ -299,7 +307,7 @@ int fat_setattr(struct dentry *dentry, struct iattr *attr)
 {
         struct msdos_sb_info *sbi = MSDOS_SB(dentry->d_sb);
         struct inode *inode = dentry->d_inode;
-        int mask, error = 0;
+        int error = 0;
         unsigned int ia_valid;
 
         lock_kernel();
@@ -332,12 +340,13 @@ int fat_setattr(struct dentry *dentry, struct iattr *attr)
                         error = 0;
                 goto out;
         }
+
         if (((attr->ia_valid & ATTR_UID) &&
              (attr->ia_uid != sbi->options.fs_uid)) ||
             ((attr->ia_valid & ATTR_GID) &&
              (attr->ia_gid != sbi->options.fs_gid)) ||
             ((attr->ia_valid & ATTR_MODE) &&
-             fat_check_mode(sbi, inode, attr->ia_mode) < 0))
+             (attr->ia_mode & ~MSDOS_VALID_MODE)))
                 error = -EPERM;
 
         if (error) {
@@ -346,15 +355,16 @@ int fat_setattr(struct dentry *dentry, struct iattr *attr)
                 goto out;
         }
 
-        error = inode_setattr(inode, attr);
-        if (error)
-                goto out;
+        /*
+         * We don't return -EPERM here. Yes, strange, but this is too
+         * old behavior.
+         */
+        if (attr->ia_valid & ATTR_MODE) {
+                if (fat_sanitize_mode(sbi, inode, &attr->ia_mode) < 0)
+                        attr->ia_valid &= ~ATTR_MODE;
+        }
 
-        if (S_ISDIR(inode->i_mode))
-                mask = sbi->options.fs_dmask;
-        else
-                mask = sbi->options.fs_fmask;
-        inode->i_mode &= S_IFMT | (S_IRWXUGO & ~mask);
+        error = inode_setattr(inode, attr);
 out:
         unlock_kernel();
         return error;