From: Douglas Gilbert <dgilbert@interlog.com>
To: Evan Green <evgreen@chromium.org>,
"James E.J. Bottomley" <jejb@linux.vnet.ibm.com>,
"Martin K. Petersen" <martin.petersen@oracle.com>,
linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: Nick Desaulniers <ndesaulniers@google.com>,
Christoph Hellwig <hch@infradead.org>,
Robb Glasser <rglasser@google.com>,
stable@vger.kernel.org
Subject: Re: [PATCH RESEND] scsi: sg: Prevent potential double frees in sg driver
Date: Tue, 2 Oct 2018 09:34:33 +1000 [thread overview]
Message-ID: <ef53fcb4-9001-c06b-779f-d40949224c98@interlog.com> (raw)
In-Reply-To: <20181001161506.100284-1-evgreen@chromium.org>
On 2018-10-02 02:15 AM, Evan Green wrote:
> From: Robb Glasser <rglasser@google.com>
>
> sg_ioctl could be spammed by requests, leading to a double free in
> __free_pages. This protects the entry points of sg_ioctl where the
> memory could be corrupted by a double call to __free_pages if multiple
> requests are happening concurrently.
Hi,
I don't like this patch. I would like to see the trace for the double
call to the __free_pages you are referring too. A test program that
show the fault, perhaps?
I have test code to "spam" the sg driver and have not seen a double
__free_pages that you refer to (see sg3_utils package version 1.44,
testing/sg_tst_async.cpp).
Currently I am dusting off 20 years of "laparoscopic" patches to the sg
driver that have made a bit of a mess of the naming and comments. Also
the 16 outstanding requests per file descriptor limit is being removed.
Then I want to add the SG_IOSUBMIT and SG_IORECEIVE ioctls proposed by
Linus Torvalds two week ago.
Executive summary: nak, without further information
Doug Gilbert
> Signed-off-by: Robb Glasser <rglasser@google.com>
> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
> Signed-off-by: Evan Green <evgreen@chromium.org>
> Cc: stable@vger.kernel.org
>
> ---
> Reposting this patch from last summer, as it looks like it fell in between
> the cracks.
>
> drivers/scsi/sg.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
> index 8a254bb46a9b..25579d8a16b5 100644
> --- a/drivers/scsi/sg.c
> +++ b/drivers/scsi/sg.c
> @@ -924,8 +924,10 @@ sg_ioctl(struct file *filp, unsigned int cmd_in, unsigned long arg)
> return -ENXIO;
> if (!access_ok(VERIFY_WRITE, p, SZ_SG_IO_HDR))
> return -EFAULT;
> + mutex_lock(&sfp->parentdp->open_rel_lock);
> result = sg_new_write(sfp, filp, p, SZ_SG_IO_HDR,
> 1, read_only, 1, &srp);
> + mutex_unlock(&sfp->parentdp->open_rel_lock);
> if (result < 0)
> return result;
> result = wait_event_interruptible(sfp->read_wait,
>
next prev parent reply other threads:[~2018-10-01 23:34 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-01 16:15 [PATCH RESEND] scsi: sg: Prevent potential double frees in sg driver Evan Green
2018-10-01 17:12 ` Nick Desaulniers
2018-10-01 17:20 ` Bart Van Assche
2018-10-01 23:34 ` Douglas Gilbert [this message]
2018-10-02 15:21 ` Evan Green
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