[PATCH 4.14 21/31] tracefs: Set the group ownership in apply_options() not parse_options()

Greg Kroah-Hartman
2022-02-28T17:28:34Z

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

commit 851e99ebeec3f4a672bb5010cf1ece095acee447 upstream.

Al Viro brought it to my attention that the dentries may not be filled
when the parse_options() is called, causing the call to set_gid() to
possibly crash. It should only be called if parse_options() succeeds
totally anyway.

He suggested the logical place to do the update is in apply_options().

Link: https://lore.kernel.org/all/20220225165219.737025658@goodmis.org/
Link: https://lkml.kernel.org/r/20220225153426.1c4cab6b@gandalf.local.home

Cc: stable@vger.kernel.org
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Fixes: 48b27b6b5191 ("tracefs: Set all files to the same group ownership as the mount option")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/tracefs/inode.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

--- a/fs/tracefs/inode.c
+++ b/fs/tracefs/inode.c
@@ -265,7 +265,6 @@ static int tracefs_parse_options(char *d
if (!gid_valid(gid))
return -EINVAL;
opts->gid = gid;
- set_gid(tracefs_mount->mnt_root, gid);
break;
case Opt_mode:
if (match_octal(&args[0], &option))
@@ -292,7 +291,9 @@ static int tracefs_apply_options(struct
inode->i_mode |= opts->mode;

inode->i_uid = opts->uid;
- inode->i_gid = opts->gid;
+
+ /* Set all the group ids to the mount option */
+ set_gid(sb->s_root, opts->gid);

return 0;
}