[PATCH] check for NULL pointer dereference in btrfs_set_acl

[Johannes Hirte <johannes.hirte@xxxxxxxxxxxxxxxxx>]

Check for for NULL pointer in btrfs_set_acl and omit calling 
posix_acl_equiv_mode in this case to avoid NULL pointer dereference there. 

Signed-off-by: Johannes Hirte <johannes.hirte@xxxxxxxxxxxxxxxxx>

diff --git a/fs/btrfs/acl.c b/fs/btrfs/acl.c
index 2e9e699..3a3a96d 100644
--- a/fs/btrfs/acl.c
+++ b/fs/btrfs/acl.c
@@ -111,13 +111,15 @@ static int btrfs_set_acl(struct btrfs_trans_handle 
*trans,

        switch (type) {
        case ACL_TYPE_ACCESS:
-               mode = inode->i_mode;
-               ret = posix_acl_equiv_mode(acl, &mode);
-               if (ret < 0)
-                       return ret;
-               ret = 0;
-               inode->i_mode = mode;
                name = POSIX_ACL_XATTR_ACCESS;
+               if (acl) {
+                       mode = inode->i_mode;
+                       ret = posix_acl_equiv_mode(acl, &mode);
+                       if (ret < 0)
+                               return ret;
+                       ret = 0;
+                       inode->i_mode = mode;
+               }
                break;
        case ACL_TYPE_DEFAULT:
                if (!S_ISDIR(inode->i_mode))
--
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