Merge tag 'vfs-6.14-rc2.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull vfs fixes from Christian Brauner:

 - Fix fsnotify FMODE_NONOTIFY* handling.

   This also disables fsnotify on all pseudo files by default apart from
   very select exceptions. This carries a regression risk so we need to
   watch out and adapt accordingly. However, it is overall a significant
   improvement over the current status quo where every rando file can
   get fsnotify enabled.

 - Cleanup and simplify lockref_init() after recent lockref changes.

 - Fix vboxfs build with gcc-15.

 - Add an assert into inode_set_cached_link() to catch corrupt links.

 - Allow users to also use an empty string check to detect whether a
   given mount option string was empty or not.

 - Fix how security options were appended to statmount()'s ->mnt_opt
   field.

 - Fix statmount() selftests to always check the returned mask.

 - Fix uninitialized value in vfs_statx_path().

 - Fix pidfs_ioctl() sanity checks to guard against ioctl() overloading
   and preserve extensibility.

* tag 'vfs-6.14-rc2.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  vfs: sanity check the length passed to inode_set_cached_link()
  pidfs: improve ioctl handling
  fsnotify: disable pre-content and permission events by default
  selftests: always check mask returned by statmount(2)
  fsnotify: disable notification by default for all pseudo files
  fs: fix adding security options to statmount.mnt_opt
  fsnotify: use accessor to set FMODE_NONOTIFY_*
  lockref: remove count argument of lockref_init
  gfs2: switch to lockref_init(..., 1)
  gfs2: use lockref_init for gl_lockref
  statmount: let unset strings be empty
  vboxsf: fix building with GCC 15
  fs/stat.c: avoid harmless garbage value problem in vfs_statx_path()

1 files changed, 30 insertions, 24 deletions

diff --git a/fs/namespace.c b/fs/namespace.c
index a3ed3f2980cb..8f1000f9f3df 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -5087,30 +5087,29 @@ static int statmount_mnt_opts(struct kstatmount *s, struct seq_file *seq)
 {
 	struct vfsmount *mnt = s->mnt;
 	struct super_block *sb = mnt->mnt_sb;
+	size_t start = seq->count;
 	int err;
 
-	if (sb->s_op->show_options) {
-		size_t start = seq->count;
-
-		err = security_sb_show_options(seq, sb);
-		if (err)
-			return err;
+	err = security_sb_show_options(seq, sb);
+	if (err)
+		return err;
 
+	if (sb->s_op->show_options) {
 		err = sb->s_op->show_options(seq, mnt->mnt_root);
 		if (err)
 			return err;
+	}
 
-		if (unlikely(seq_has_overflowed(seq)))
-			return -EAGAIN;
+	if (unlikely(seq_has_overflowed(seq)))
+		return -EAGAIN;
 
-		if (seq->count == start)
-			return 0;
+	if (seq->count == start)
+		return 0;
 
-		/* skip leading comma */
-		memmove(seq->buf + start, seq->buf + start + 1,
-			seq->count - start - 1);
-		seq->count--;
-	}
+	/* skip leading comma */
+	memmove(seq->buf + start, seq->buf + start + 1,
+		seq->count - start - 1);
+	seq->count--;
 
 	return 0;
 }
@@ -5191,39 +5190,45 @@ static int statmount_string(struct kstatmount *s, u64 flag)
 	size_t kbufsize;
 	struct seq_file *seq = &s->seq;
 	struct statmount *sm = &s->sm;
-	u32 start = seq->count;
+	u32 start, *offp;
+
+	/* Reserve an empty string at the beginning for any unset offsets */
+	if (!seq->count)
+		seq_putc(seq, 0);
+
+	start = seq->count;
 
 	switch (flag) {
 	case STATMOUNT_FS_TYPE:
-		sm->fs_type = start;
+		offp = &sm->fs_type;
 		ret = statmount_fs_type(s, seq);
 		break;
 	case STATMOUNT_MNT_ROOT:
-		sm->mnt_root = start;
+		offp = &sm->mnt_root;
 		ret = statmount_mnt_root(s, seq);
 		break;
 	case STATMOUNT_MNT_POINT:
-		sm->mnt_point = start;
+		offp = &sm->mnt_point;
 		ret = statmount_mnt_point(s, seq);
 		break;
 	case STATMOUNT_MNT_OPTS:
-		sm->mnt_opts = start;
+		offp = &sm->mnt_opts;
 		ret = statmount_mnt_opts(s, seq);
 		break;
 	case STATMOUNT_OPT_ARRAY:
-		sm->opt_array = start;
+		offp = &sm->opt_array;
 		ret = statmount_opt_array(s, seq);
 		break;
 	case STATMOUNT_OPT_SEC_ARRAY:
-		sm->opt_sec_array = start;
+		offp = &sm->opt_sec_array;
 		ret = statmount_opt_sec_array(s, seq);
 		break;
 	case STATMOUNT_FS_SUBTYPE:
-		sm->fs_subtype = start;
+		offp = &sm->fs_subtype;
 		statmount_fs_subtype(s, seq);
 		break;
 	case STATMOUNT_SB_SOURCE:
-		sm->sb_source = start;
+		offp = &sm->sb_source;
 		ret = statmount_sb_source(s, seq);
 		break;
 	default:
@@ -5251,6 +5256,7 @@ static int statmount_string(struct kstatmount *s, u64 flag)
 
 	seq->buf[seq->count++] = '\0';
 	sm->mask |= flag;
+	*offp = start;
 	return 0;
 }