From: Jason Gunthorpe <jgg@ziepe.ca>
To: Hillf Danton <hdanton@sina.com>
Cc: syzbot <syzbot+cc6fc752b3819e082d0c@syzkaller.appspotmail.com>,
dledford@redhat.com, leon@kernel.org,
linux-kernel@vger.kernel.org, linux-rdma@vger.kernel.org,
syzkaller-bugs@googlegroups.com
Subject: Re: KASAN: use-after-free Read in ucma_close (2)
Date: Fri, 11 Sep 2020 08:57:50 -0300 [thread overview]
Message-ID: <20200911115750.GA1137957@ziepe.ca> (raw)
In-Reply-To: <20200911041640.20652-1-hdanton@sina.com>
On Fri, Sep 11, 2020 at 12:16:40PM +0800, Hillf Danton wrote:
> Detect race destroying ctx in order to avoid UAF.
>
> +++ b/drivers/infiniband/core/ucma.c
> @@ -625,6 +625,10 @@ static ssize_t ucma_destroy_id(struct uc
> return PTR_ERR(ctx);
>
> mutex_lock(&ctx->file->mut);
> + if (ctx->destroying == 1) {
> + mutex_unlock(&ctx->file->mut);
> + return -ENXIO;
> + }
> ctx->destroying = 1;
> mutex_unlock(&ctx->file->mut);
>
> @@ -1826,6 +1830,8 @@ static int ucma_close(struct inode *inod
>
> mutex_lock(&file->mut);
> list_for_each_entry_safe(ctx, tmp, &file->ctx_list, list) {
> + if (ctx->destroying == 1)
> + continue;
> ctx->destroying = 1;
> mutex_unlock(&file->mut);
>
ucma_destroy_id() is called from write() and ucma_close is release(),
so there is no way these can race?
Jason
next prev parent reply other threads:[~2020-09-11 11:58 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-10 14:09 KASAN: use-after-free Read in ucma_close (2) syzbot
[not found] ` <20200911041640.20652-1-hdanton@sina.com>
2020-09-11 11:57 ` Jason Gunthorpe [this message]
[not found] ` <20200911152017.18644-1-hdanton@sina.com>
2020-09-11 17:01 ` Jason Gunthorpe
[not found] ` <20200912013514.18380-1-hdanton@sina.com>
2020-09-14 15:01 ` Jason Gunthorpe
2020-09-11 12:02 ` Jason Gunthorpe
2020-09-11 15:49 ` syzbot
2020-09-11 18:19 ` Jason Gunthorpe
2020-09-11 20:53 ` syzbot
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