cachefiles: fix memory leak in cachefiles_add_cache()

commit e21a2f17566cbd64926fb8f16323972f7a064444 upstream.

The following memory leak was reported after unbinding /dev/cachefiles:

==================================================================
unreferenced object 0xffff9b674176e3c0 (size 192):
  comm "cachefilesd2", pid 680, jiffies 4294881224
  hex dump (first 32 bytes):
    01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace (crc ea38a44b):
    [<ffffffff8eb8a1a5>] kmem_cache_alloc+0x2d5/0x370
    [<ffffffff8e917f86>] prepare_creds+0x26/0x2e0
    [<ffffffffc002eeef>] cachefiles_determine_cache_security+0x1f/0x120
    [<ffffffffc00243ec>] cachefiles_add_cache+0x13c/0x3a0
    [<ffffffffc0025216>] cachefiles_daemon_write+0x146/0x1c0
    [<ffffffff8ebc4a3b>] vfs_write+0xcb/0x520
    [<ffffffff8ebc5069>] ksys_write+0x69/0xf0
    [<ffffffff8f6d4662>] do_syscall_64+0x72/0x140
    [<ffffffff8f8000aa>] entry_SYSCALL_64_after_hwframe+0x6e/0x76
==================================================================

Put the reference count of cache_cred in cachefiles_daemon_unbind() to
fix the problem. And also put cache_cred in cachefiles_add_cache() error
branch to avoid memory leaks.

Fixes: 9ae326a69004 ("CacheFiles: A cache that backs onto a mounted filesystem")
CC: stable@vger.kernel.org
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Link: https://lore.kernel.org/r/20240217081431.796809-1-libaokun1@huawei.com
Acked-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jingbo Xu <jefflexu@linux.alibaba.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/cachefiles/bind.c b/fs/cachefiles/bind.c
index 146291be6263753838c8a15b902aff253b3caba6..8609a94639c88b49ec06af565c20d7d98eb948b9 100644 (file)
--- a/fs/cachefiles/bind.c
+++ b/fs/cachefiles/bind.c
@@ -249,6 +249,8 @@ error_open_root:
        kmem_cache_free(cachefiles_object_jar, fsdef);
 error_root_object:
        cachefiles_end_secure(cache, saved_cred);
+       put_cred(cache->cache_cred);
+       cache->cache_cred = NULL;
        pr_err("Failed to register: %d\n", ret);
        return ret;
 }
@@ -269,6 +271,7 @@ void cachefiles_daemon_unbind(struct cachefiles_cache *cache)
 
        dput(cache->graveyard);
        mntput(cache->mnt);
+       put_cred(cache->cache_cred);
 
        kfree(cache->rootdirname);
        kfree(cache->secctx);