From: Kees Cook <keescook@chromium.org>
To: Christoph Hellwig <hch@lst.de>
Cc: kernel test robot <oliver.sang@intel.com>,
"Martin K. Petersen" <martin.petersen@oracle.com>,
Bart Van Assche <bvanassche@acm.org>,
John Garry <john.garry@huawei.com>,
LKML <linux-kernel@vger.kernel.org>,
lkp@lists.01.org, lkp@intel.com,
"Matthew Wilcox (Oracle)" <willy@infradead.org>,
linux-mm@kvack.org, linux-hardening@vger.kernel.org
Subject: Re: [scsi] 6aded12b10: kernel_BUG_at_mm/usercopy.c
Date: Wed, 23 Mar 2022 15:33:30 -0700 [thread overview]
Message-ID: <202203231531.02D8297F77@keescook> (raw)
In-Reply-To: <20220323154739.GA816@lst.de>
On Wed, Mar 23, 2022 at 04:47:39PM +0100, Christoph Hellwig wrote:
> On Wed, Mar 23, 2022 at 08:40:30AM -0700, Kees Cook wrote:
> > Regardless, I'm concerned that disabling PAGESPAN will just uncover
> > further checks, though. Where is allocation happening? The check is here:
>
> blk_mq_alloc_rqs, using alloc_pages_node. This hasn't actually changed
> with this comment. Just the size of the allocation shrunk, probably
> leading to the span of pages.
Okay, the page allocator _should_ be fine for that. In the mean time,
lkp should probably just disable PAGESPAN.
> > I *think* the allocation is happening in scsi_ioctl_reset()? But that's
> > a plain kmalloc(), so I'm not sure why PAGESPAN would have tripped...
> > are there other allocation paths?
>
> scsi_ioctl_reset is the odd one out and does also allocate a request,
> but that request is never used for user copies (and that whole hacky
> side path needs to go away, there is a huge series that needs to be
> finished to sort this out).
Gotcha!
--
Kees Cook
next prev parent reply other threads:[~2022-03-23 22:33 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-20 14:34 [scsi] 6aded12b10: kernel_BUG_at_mm/usercopy.c kernel test robot
2022-03-23 7:14 ` Christoph Hellwig
2022-03-23 15:40 ` Kees Cook
2022-03-23 15:42 ` Matthew Wilcox
2022-03-23 22:30 ` Kees Cook
2022-03-23 15:47 ` Christoph Hellwig
2022-03-23 22:33 ` Kees Cook [this message]
2022-03-24 6:48 ` Christoph Hellwig
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