On Fri, Apr 25, 2025 at 5:25 AM alexjlzheng@gmail.com wrote:
From: Jinliang Zheng alexjlzheng@tencent.com
Consider the following module code:
static struct dentry *dentry;
static int __init securityfs_test_init(void) { dentry = securityfs_create_dir("standon", NULL); return PTR_ERR(dentry); }
static void __exit securityfs_test_exit(void) { securityfs_remove(dentry); }
module_init(securityfs_test_init); module_exit(securityfs_test_exit);
and then:
insmod /path/to/thismodule cd /sys/kernel/security/standon <- we hold 'standon' rmmod thismodule <- 'standon' don't go away insmod /path/to/thismodule <- Failed: File exists!
A quick procedural note, and you may have gotten an email about this from the stable kernel folks already, you generally shouldn't add the stable alias to your emails directly. You may want to look at the kernel docs on the stable kernel if you haven't already:
* https://docs.kernel.org/process/stable-kernel-rules.html
Beyond that, we don't currently support dynamically loading or unloading LSMs so the immediate response to the reproducer above is "don't do that, we don't support it" :) However, if you see a similar problem with a LSM properly registered with the running kernel please let us know.
Fix this by adding d_delete() in securityfs_remove().
Fixes: b67dbf9d4c198 ("[PATCH] add securityfs for all LSMs to use") Signed-off-by: Jinliang Zheng alexjlzheng@tencent.com Cc: stable@vger.kernel.org
security/inode.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/security/inode.c b/security/inode.c index da3ab44c8e57..d99baf26350a 100644 --- a/security/inode.c +++ b/security/inode.c @@ -306,6 +306,7 @@ void securityfs_remove(struct dentry *dentry) simple_rmdir(dir, dentry); else simple_unlink(dir, dentry);
d_delete(dentry); dput(dentry); } inode_unlock(dir);-- 2.49.0