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 --- fs/cachefiles/bind.c | 3 +++ 1 file changed, 3 insertions(+)

diff --git a/fs/cachefiles/bind.c b/fs/cachefiles/bind.c index 4a717d400807..9b34d46bf8ee 100644 --- a/fs/cachefiles/bind.c +++ b/fs/cachefiles/bind.c @@ -249,6 +249,8 @@ static int cachefiles_daemon_add_cache(struct cachefiles_cache *cache) 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);