cachefiles_ondemand_init_object() as called from cachefiles_open_file() and
cachefiles_create_tmpfile() does not check if object->ondemand is set
before dereferencing it, leading to an oops something like:
RIP: 0010:cachefiles_ondemand_init_object+0x9/0x41
...
Call Trace:
<TASK>
cachefiles_open_file+0xc9/0x187
cachefiles_lookup_cookie+0x122/0x2be
fscache_cookie_state_machine+0xbe/0x32b
fscache_cookie_worker+0x1f/0x2d
process_one_work+0x136/0x208
process_scheduled_works+0x3a/0x41
worker_thread+0x1a2/0x1f6
kthread+0xca/0xd2
ret_from_fork+0x21/0x33
Fix this by making cachefiles_ondemand_init_object() return immediately if
cachefiles->ondemand is NULL.
Fixes: 3c5ecfe16e76 ("cachefiles: extract ondemand info field from cachefiles_object")
Reported-by: Marc Dionne <marc.dionne@xxxxxxxxxxxx>
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
cc: Gao Xiang <xiang@xxxxxxxxxx>
cc: Chao Yu <chao@xxxxxxxxxx>
cc: Yue Hu <huyue2@xxxxxxxxxxx>
cc: Jeffle Xu <jefflexu@xxxxxxxxxxxxxxxxx>
cc: linux-erofs@xxxxxxxxxxxxxxxx
cc: netfs@xxxxxxxxxxxxxxx
cc: linux-fsdevel@xxxxxxxxxxxxxxx
---
Notes:
Changes
=======
ver #2)
- Move check of object->ondemand into cachefiles_ondemand_init_object()
fs/cachefiles/ondemand.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/fs/cachefiles/ondemand.c b/fs/cachefiles/ondemand.c
index 5fd74ec60bef..4ba42f1fa3b4 100644
--- a/fs/cachefiles/ondemand.c
+++ b/fs/cachefiles/ondemand.c
@@ -539,6 +539,9 @@ int cachefiles_ondemand_init_object(struct cachefiles_object *object)
struct fscache_volume *volume = object->volume->vcookie;
size_t volume_key_size, cookie_key_size, data_len;
+ if (!object->ondemand)
+ return 0;
+
/*
* CacheFiles will firstly check the cache file under the root cache
* directory. If the coherency check failed, it will fallback to
