diff options
author | Baokun Li <libaokun1@huawei.com> | 2024-05-22 14:43:03 +0300 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-06-21 15:40:16 +0300 |
commit | 96caaf31b16b75c814d1770cdea8fb673ca8681f (patch) | |
tree | 46f1f80ff75b757a81bfc3e3f800b772255ab136 /fs | |
parent | 93064676a2820420a2d37d7c8289f277fe20793d (diff) | |
download | linux-96caaf31b16b75c814d1770cdea8fb673ca8681f.tar.xz |
cachefiles: add spin_lock for cachefiles_ondemand_info
[ Upstream commit 0a790040838c736495d5afd6b2d636f159f817f1 ]
The following concurrency may cause a read request to fail to be completed
and result in a hung:
t1 | t2
---------------------------------------------------------
cachefiles_ondemand_copen
req = xa_erase(&cache->reqs, id)
// Anon fd is maliciously closed.
cachefiles_ondemand_fd_release
xa_lock(&cache->reqs)
cachefiles_ondemand_set_object_close(object)
xa_unlock(&cache->reqs)
cachefiles_ondemand_set_object_open
// No one will ever close it again.
cachefiles_ondemand_daemon_read
cachefiles_ondemand_select_req
// Get a read req but its fd is already closed.
// The daemon can't issue a cread ioctl with an closed fd, then hung.
So add spin_lock for cachefiles_ondemand_info to protect ondemand_id and
state, thus we can avoid the above problem in cachefiles_ondemand_copen()
by using ondemand_id to determine if fd has been closed.
Fixes: c8383054506c ("cachefiles: notify the user daemon when looking up cookie")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Link: https://lore.kernel.org/r/20240522114308.2402121-8-libaokun@huaweicloud.com
Acked-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'fs')
-rw-r--r-- | fs/cachefiles/internal.h | 1 | ||||
-rw-r--r-- | fs/cachefiles/ondemand.c | 35 |
2 files changed, 35 insertions, 1 deletions
diff --git a/fs/cachefiles/internal.h b/fs/cachefiles/internal.h index 7745b8abc3aa..45c8bed60538 100644 --- a/fs/cachefiles/internal.h +++ b/fs/cachefiles/internal.h @@ -55,6 +55,7 @@ struct cachefiles_ondemand_info { int ondemand_id; enum cachefiles_object_state state; struct cachefiles_object *object; + spinlock_t lock; }; /* diff --git a/fs/cachefiles/ondemand.c b/fs/cachefiles/ondemand.c index 3dd002108a87..7b667ddc84ca 100644 --- a/fs/cachefiles/ondemand.c +++ b/fs/cachefiles/ondemand.c @@ -16,13 +16,16 @@ static int cachefiles_ondemand_fd_release(struct inode *inode, struct cachefiles_object *object = file->private_data; struct cachefiles_cache *cache = object->volume->cache; struct cachefiles_ondemand_info *info = object->ondemand; - int object_id = info->ondemand_id; + int object_id; struct cachefiles_req *req; XA_STATE(xas, &cache->reqs, 0); xa_lock(&cache->reqs); + spin_lock(&info->lock); + object_id = info->ondemand_id; info->ondemand_id = CACHEFILES_ONDEMAND_ID_CLOSED; cachefiles_ondemand_set_object_close(object); + spin_unlock(&info->lock); /* Only flush CACHEFILES_REQ_NEW marked req to avoid race with daemon_read */ xas_for_each_marked(&xas, req, ULONG_MAX, CACHEFILES_REQ_NEW) { @@ -122,6 +125,7 @@ int cachefiles_ondemand_copen(struct cachefiles_cache *cache, char *args) { struct cachefiles_req *req; struct fscache_cookie *cookie; + struct cachefiles_ondemand_info *info; char *pid, *psize; unsigned long id; long size; @@ -172,6 +176,33 @@ int cachefiles_ondemand_copen(struct cachefiles_cache *cache, char *args) goto out; } + info = req->object->ondemand; + spin_lock(&info->lock); + /* + * The anonymous fd was closed before copen ? Fail the request. + * + * t1 | t2 + * --------------------------------------------------------- + * cachefiles_ondemand_copen + * req = xa_erase(&cache->reqs, id) + * // Anon fd is maliciously closed. + * cachefiles_ondemand_fd_release + * xa_lock(&cache->reqs) + * cachefiles_ondemand_set_object_close(object) + * xa_unlock(&cache->reqs) + * cachefiles_ondemand_set_object_open + * // No one will ever close it again. + * cachefiles_ondemand_daemon_read + * cachefiles_ondemand_select_req + * + * Get a read req but its fd is already closed. The daemon can't + * issue a cread ioctl with an closed fd, then hung. + */ + if (info->ondemand_id == CACHEFILES_ONDEMAND_ID_CLOSED) { + spin_unlock(&info->lock); + req->error = -EBADFD; + goto out; + } cookie = req->object->cookie; cookie->object_size = size; if (size) @@ -181,6 +212,7 @@ int cachefiles_ondemand_copen(struct cachefiles_cache *cache, char *args) trace_cachefiles_ondemand_copen(req->object, id, size); cachefiles_ondemand_set_object_open(req->object); + spin_unlock(&info->lock); wake_up_all(&cache->daemon_pollwq); out: @@ -596,6 +628,7 @@ int cachefiles_ondemand_init_obj_info(struct cachefiles_object *object, return -ENOMEM; object->ondemand->object = object; + spin_lock_init(&object->ondemand->lock); INIT_WORK(&object->ondemand->ondemand_work, ondemand_object_worker); return 0; } |