Follow @Openwall on Twitter for new release announcements and other news
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Wed, 17 Mar 2021 12:40:41 +0000
From: John Haxby <>
To: "" <>
Subject: Re: Use After Free and Double Free bugs in Linux
 Kernel mainline

This one isn't a security bug:

> On 17 Mar 2021, at 11:53, wrote:
> Bug2: nvme/rdma: Fix a use after free in nvmet_rdma_write_data_done
> Commit Url:
> In nvmet_rdma_write_data_done, rsp is recoverd by wc->wr_cqe
> and freed by nvmet_rdma_release_rsp(). But after that, pr_info()
> used the freed chunk's member object and could leak the freed
> chunk address with wc->wr_cqe by computing the offset.
> drivers/nvme/target/rdma.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
> diff --git a/drivers/nvme/target/rdma.c b/drivers/nvme/target/rdma.c
> index 06b6b742bb21..6c1f3ab7649c 100644
> --- a/drivers/nvme/target/rdma.c
> +++ b/drivers/nvme/target/rdma.c
> @@ -802,9 +802,8 @@ static void nvmet_rdma_write_data_done(struct ib_cq *cq, struct ib_wc *wc)
> 		nvmet_req_uninit(&rsp->req);
> 		nvmet_rdma_release_rsp(rsp);
> 		if (wc->status != IB_WC_WR_FLUSH_ERR) {
> -			pr_info("RDMA WRITE for CQE 0x%p failed with status %s (%d).\n",
> -				wc->wr_cqe, ib_wc_status_msg(wc->status),
> -				wc->status);
> +			pr_info("RDMA WRITE for CQE failed with status %s (%d).\n",
> +				ib_wc_status_msg(wc->status), wc->status);
> 			nvmet_rdma_error_comp(queue);
> 		}
> 		return;

Commit ad67b74d2469 ("printk: hash addresses printed with %p") back in 2017 made '%p' a non-security issue. That commit noted that there were approximately 14,000 places in the kernel where there was an address printed with %p.  Rather than 14,000 CVEs :) this was fixed once and once only by that commit.

That's not to say that this "0x%p" doesn't have a problem: for a start you don't need the "0x" because %p prints one anyway. That point is moot, though, because no one objected to just removing the pointer.  The commit message is wrong though: it doesn't leak an address.


Powered by blists - more mailing lists

Please check out the Open Source Software Security Wiki, which is counterpart to this mailing list.

Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.