On 1/23/24 6:32 AM, David Howells wrote: > 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 Reviewed-by: Jingbo Xu <jefflexu@xxxxxxxxxxxxxxxxx> -- Thanks, Jingbo