From: Al Viro <viro@zeniv.linux.org.uk>
To: linux-block@vger.kernel.org
Subject: UAF in blk_add_rq_to_plug()?
Date: Mon, 31 Oct 2022 22:12:57 +0000 [thread overview]
Message-ID: <Y2BIad98er4QsbZY@ZenIV> (raw)
static void blk_add_rq_to_plug(struct blk_plug *plug, struct request *rq)
{
struct request *last = rq_list_peek(&plug->mq_list);
Suppose it's not NULL...
if (!plug->rq_count) {
trace_block_plug(rq->q);
} else if (plug->rq_count >= blk_plug_max_rq_count(plug) ||
(!blk_queue_nomerges(rq->q) &&
blk_rq_bytes(last) >= BLK_PLUG_FLUSH_SIZE)) {
... and we went here:
blk_mq_flush_plug_list(plug, false);
All requests, including the one last points to, might get fed ->queue_rq()
here. At which point there seems to be nothing to prevent them getting
completed and freed on another CPU, possibly before we return here.
trace_block_plug(rq->q);
}
if (!plug->multiple_queues && last && last->q != rq->q)
... and here we dereference last.
Shouldn't we reset last to NULL after the call of blk_mq_flush_plug_list()
above?
next reply other threads:[~2022-10-31 22:13 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-31 22:12 Al Viro [this message]
2022-10-31 22:42 ` UAF in blk_add_rq_to_plug()? Jens Axboe
2022-10-31 23:35 ` Al Viro
2022-11-01 0:03 ` Jens Axboe
2022-11-01 0:06 ` Jens Axboe
2022-11-01 0:54 ` Al Viro
2022-11-01 2:23 ` Jens Axboe
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=Y2BIad98er4QsbZY@ZenIV \
--to=viro@zeniv.linux.org.uk \
--cc=linux-block@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.