On 1/22/24 8:38 PM, 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 the calls to cachefiles_ondemand_init_object() > conditional. > > 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 > --- > fs/cachefiles/namei.c | 16 ++++++++++------ > 1 file changed, 10 insertions(+), 6 deletions(-) > > diff --git a/fs/cachefiles/namei.c b/fs/cachefiles/namei.c > index 7ade836beb58..180594d24c44 100644 > --- a/fs/cachefiles/namei.c > +++ b/fs/cachefiles/namei.c > @@ -473,9 +473,11 @@ struct file *cachefiles_create_tmpfile(struct cachefiles_object *object) > if (!cachefiles_mark_inode_in_use(object, file_inode(file))) > WARN_ON(1); > > - ret = cachefiles_ondemand_init_object(object); > - if (ret < 0) > - goto err_unuse; > + if (object->ondemand) { > + ret = cachefiles_ondemand_init_object(object); > + if (ret < 0) > + goto err_unuse; > + } I'm not sure if object->ondemand shall be checked by the caller or inside cachefiles_ondemand_init_object(), as cachefiles_ondemand_clean_object() is also called without checking object->ondemand. cachefiles_ondemand_clean_object() won't trigger the NULL oops as the called cachefiles_ondemand_send_req() will actually checks that. Anyway this patch looks good to me. Thanks. Reviewed-by: Jingbo Xu <jefflexu@xxxxxxxxxxxxxxxxx> > > ni_size = object->cookie->object_size; > ni_size = round_up(ni_size, CACHEFILES_DIO_BLOCK_SIZE); > @@ -579,9 +581,11 @@ static bool cachefiles_open_file(struct cachefiles_object *object, > } > _debug("file -> %pd positive", dentry); > > - ret = cachefiles_ondemand_init_object(object); > - if (ret < 0) > - goto error_fput; > + if (object->ondemand) { > + ret = cachefiles_ondemand_init_object(object); > + if (ret < 0) > + goto error_fput; > + } > > ret = cachefiles_check_auxdata(object, file); > if (ret < 0) -- Thanks, Jingbo