[PATCH AUTOSEL 6.6 35/40] eventfs: Do not allow NULL parent to eventfs_start_creating()

Sasha Levin
2023-11-28T21:09:25Z

From: "Steven Rostedt (Google)" <rostedt@goodmis.org>

[ Upstream commit fc4561226feaad5fcdcb55646c348d77b8ee69c5 ]

The eventfs directory is dynamically created via the meta data supplied by
the existing trace events. All files and directories in eventfs has a
parent. Do not allow NULL to be passed into eventfs_start_creating() as
the parent because that should never happen. Warn if it does.

Link: https://lkml.kernel.org/r/20231121231112.693841807@goodmis.org

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/tracefs/inode.c | 13 ++++---------
1 file changed, 4 insertions(+), 9 deletions(-)

diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c
index 891653ba9cf35..0292c6a2bed9f 100644
--- a/fs/tracefs/inode.c
+++ b/fs/tracefs/inode.c
@@ -509,20 +509,15 @@ struct dentry *eventfs_start_creating(const char *name, struct dentry *parent)
struct dentry *dentry;
int error;

+ /* Must always have a parent. */
+ if (WARN_ON_ONCE(!parent))
+ return ERR_PTR(-EINVAL);
+
error = simple_pin_fs(&trace_fs_type, &tracefs_mount,
&tracefs_mount_count);
if (error)
return ERR_PTR(error);

- /*
- * If the parent is not specified, we create it in the root.
- * We need the root dentry to do this, which is in the super
- * block. A pointer to that is in the struct vfsmount that we
- * have around.
- */
- if (!parent)
- parent = tracefs_mount->mnt_root;
-
if (unlikely(IS_DEADDIR(parent->d_inode)))
dentry = ERR_PTR(-ENOENT);
else
--
2.42.0