The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y git checkout FETCH_HEAD git cherry-pick -x e21a2f17566cbd64926fb8f16323972f7a064444 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2024022636-prevail-headway-01c9@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^..

Possible dependencies:

e21a2f17566c ("cachefiles: fix memory leak in cachefiles_add_cache()") d1065b0a6fd9 ("cachefiles: Implement cache registration and withdrawal") 32759f7d7af5 ("cachefiles: Implement a function to get/create a directory in the cache") 1bd9c4e4f049 ("vfs, cachefiles: Mark a backing file in use with an inode flag") 80f94f29f677 ("cachefiles: Provide a function to check how much space there is") 8667d434b2a9 ("cachefiles: Register a miscdev and parse commands over it") 254947d47945 ("cachefiles: Add security derivation") 1493bf74bcf2 ("cachefiles: Add cache error reporting macro") ecf5a6ce15f9 ("cachefiles: Add a couple of tracepoints for logging errors") a70f6526267e ("cachefiles: Add some error injection support") 8390fbc46570 ("cachefiles: Define structs") 77443f6171f3 ("cachefiles: Introduce rewritten driver") 850cba069c26 ("cachefiles: Delete the cachefiles driver pending rewrite") b6773cdb0e9f ("Merge tag 'for-5.16/ki_complete-2021-10-29' of git://git.kernel.dk/linux-block")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From e21a2f17566cbd64926fb8f16323972f7a064444 Mon Sep 17 00:00:00 2001 From: Baokun Li libaokun1@huawei.com Date: Sat, 17 Feb 2024 16:14:31 +0800 Subject: [PATCH] cachefiles: fix memory leak in cachefiles_add_cache()

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

diff --git a/fs/cachefiles/cache.c b/fs/cachefiles/cache.c index 7077f72e6f47..f449f7340aad 100644 --- a/fs/cachefiles/cache.c +++ b/fs/cachefiles/cache.c @@ -168,6 +168,8 @@ int cachefiles_add_cache(struct cachefiles_cache *cache) dput(root); error_open_root: cachefiles_end_secure(cache, saved_cred); + put_cred(cache->cache_cred); + cache->cache_cred = NULL; error_getsec: fscache_relinquish_cache(cache_cookie); cache->cache = NULL; diff --git a/fs/cachefiles/daemon.c b/fs/cachefiles/daemon.c index 3f24905f4066..6465e2574230 100644 --- a/fs/cachefiles/daemon.c +++ b/fs/cachefiles/daemon.c @@ -816,6 +816,7 @@ static void cachefiles_daemon_unbind(struct cachefiles_cache *cache) cachefiles_put_directory(cache->graveyard); cachefiles_put_directory(cache->store); mntput(cache->mnt); + put_cred(cache->cache_cred);

kfree(cache->rootdirname); kfree(cache->secctx);