Re: usercopy whitelist woe in scsi_sense_cache

[Kees Cook <keescook@xxxxxxxxxxxx>]

On Tue, Apr 17, 2018 at 1:46 PM, Kees Cook <keescook@xxxxxxxxxxxx> wrote:
> I see elv.priv[1] assignments made in a few places -- is it possible
> there is some kind of uninitialized-but-not-NULL state that can leak
> in there?

Got it. This fixes it for me:

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 0dc9e341c2a7..859df3160303 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -363,7 +363,7 @@ static struct request *blk_mq_get_request(struct
request_queue *q,

        rq = blk_mq_rq_ctx_init(data, tag, op);
        if (!op_is_flush(op)) {
-               rq->elv.icq = NULL;
+               memset(&rq->elv, 0, sizeof(rq->elv));
                if (e && e->type->ops.mq.prepare_request) {
                        if (e->type->icq_cache && rq_ioc(bio))
                                blk_mq_sched_assign_ioc(rq, bio);
@@ -461,7 +461,7 @@ void blk_mq_free_request(struct request *rq)
                        e->type->ops.mq.finish_request(rq);
                if (rq->elv.icq) {
                        put_io_context(rq->elv.icq->ioc);
-                       rq->elv.icq = NULL;
+                       memset(&rq->elv, 0, sizeof(rq->elv));
                }
        }



-- 
Kees Cook
Pixel Security