From: Yueyi Li <liyueyi@live.com>
To: "Markus F.X.J. Oberhumer" <markus@oberhumer.com>,
"dsterba@suse.cz" <dsterba@suse.cz>,
"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
"w@1wt.eu" <w@1wt.eu>,
"donb@securitymouse.com" <donb@securitymouse.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2] lzo: fix ip overrun during compress.
Date: Wed, 5 Dec 2018 03:07:58 +0000 [thread overview]
Message-ID: <SN1PR13MB030484F09EE8A00DB094CDFADFA80@SN1PR13MB0304.namprd13.prod.outlook.com> (raw)
In-Reply-To: <5C0654EE.5040001@oberhumer.com>
Hi Markus,
Thanks for your review.
On 2018/12/4 18:20, Markus F.X.J. Oberhumer wrote:
> Hi,
>
> I don't think that address space wraparound is legal in C, but I
> understand that we are in kernel land and if you really want to
> compress the last virtual page 0xfffffffffffff000 the following
> small patch should fix that dubious case.
I guess the VA 0xfffffffffffff000 is available because KASLR be
enabled. For this case we can see:
crash> kmem 0xfffffffffffff000
PAGE PHYSICAL MAPPING INDEX CNT FLAGS
ffffffbfffffffc0 1fffff000 ffffffff1655ecb9 7181fd5 2
8000000000064209 locked,uptodate,owner_priv_1,writeback,reclaim,swapbacked
> This also avoids slowing down the the hot path of the compression
> core function.
>
> Cheers,
> Markus
>
>
>
> diff --git a/lib/lzo/lzo1x_compress.c b/lib/lzo/lzo1x_compress.c
> index 236eb21167b5..959dec45f6fe 100644
> --- a/lib/lzo/lzo1x_compress.c
> +++ b/lib/lzo/lzo1x_compress.c
> @@ -224,8 +224,8 @@ int lzo1x_1_compress(const unsigned char *in, size_t in_len,
>
> while (l > 20) {
> size_t ll = l <= (M4_MAX_OFFSET + 1) ? l : (M4_MAX_OFFSET + 1);
> - uintptr_t ll_end = (uintptr_t) ip + ll;
> - if ((ll_end + ((t + ll) >> 5)) <= ll_end)
> + // check for address space wraparound
> + if (((uintptr_t) ip + ll + ((t + ll) >> 5)) <= (uintptr_t) ip)
> break;
> BUILD_BUG_ON(D_SIZE * sizeof(lzo_dict_t) > LZO1X_1_MEM_COMPRESS);
> memset(wrkmem, 0, D_SIZE * sizeof(lzo_dict_t));
I parsed panic ramdump and loaded CPU register values, can see:
-000|lzo1x_1_do_compress(
| in = 0xFFFFFFFFFFFFF000,
| ?,
| out = 0xFFFFFFFF2E2EE000,
| out_len = 0xFFFFFF801CAA3510,
| ?,
| wrkmem = 0xFFFFFFFF4EBC0000)
| dict = 0xFFFFFFFF4EBC0000
| op = 0x1
| ip = 0x9
| ii = 0x9
| in_end = 0x0
| ip_end = 0xFFFFFFFFFFFFFFEC
| m_len = 0
| m_off = 1922
-001|lzo1x_1_compress(
| in = 0xFFFFFFFFFFFFF000,
| in_len = 0,
| out = 0xFFFFFFFF2E2EE000,
| out_len = 0x00000001616FB7D0,
| wrkmem = 0xFFFFFFFF4EBC0000)
| ip = 0xFFFFFFFFFFFFF000
| op = 0xFFFFFFFF2E2EE000
| l = 4096
| t = 0
| ll = 4096
ll = l = in_len = 4096 in lzo1x_1_compress, so your patch is working
for this panic case, but, I`m
not sure, is it possible that in = 0xFFFFFFFFFFFFF000 and in_len < 4096?
Thanks,
Yueyi
next prev parent reply other threads:[~2018-12-05 3:08 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-28 7:31 [PATCH v2] lzo: fix ip overrun during compress Yueyi Li
2018-11-28 13:52 ` David Sterba
2018-11-28 14:15 ` Willy Tarreau
2018-11-29 16:49 ` Dave Rodgman
2018-11-30 3:05 ` Yueyi Li
2018-11-30 12:20 ` Dave Rodgman
2018-12-03 2:46 ` Yueyi Li
2018-12-03 3:05 ` Yueyi Li
2018-12-04 10:20 ` Markus F.X.J. Oberhumer
2018-12-05 3:07 ` Yueyi Li [this message]
2018-12-06 15:03 ` Markus F.X.J. Oberhumer
2018-12-12 5:21 ` Yueyi Li
2018-12-12 12:35 ` Markus F.X.J. Oberhumer
2018-12-14 13:56 ` Richard Weinberger
2018-12-14 16:46 ` Kees Cook
2018-12-16 16:56 ` Markus F.X.J. Oberhumer
2018-12-18 9:25 ` Yueyi Li
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