debugfs: be more robust at handling improper input in debugfs_lookup()

commit bc6de804d3 upstream.

debugfs_lookup() doesn't like it if it is passed an illegal name
pointer, or if the filesystem isn't even initialized yet.  If either of
these happen, it will crash the system, so fix it up by properly testing
for valid input and that we are up and running before trying to find a
file in the filesystem.

Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: stable <stable@vger.kernel.org>
Reported-by: Michael Walle <michael@walle.cc>
Tested-by: Michael Walle <michael@walle.cc>
Tested-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210218100818.3622317-1-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Greg Kroah-Hartman 2021-02-18 11:08:17 +01:00
parent 2a7e48dc38
commit 0bd665240a

View file

@ -297,7 +297,7 @@ struct dentry *debugfs_lookup(const char *name, struct dentry *parent)
{
struct dentry *dentry;
if (IS_ERR(parent))
if (!debugfs_initialized() || IS_ERR_OR_NULL(name) || IS_ERR(parent))
return NULL;
if (!parent)