From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Subject: Re: [PATCH v2] pktcdvd: Fix possible Spectre-v1 for pkt_devs From: "Gustavo A. R. Silva" To: Jinbum Park , axboe@kernel.dk, bart.vanassche@wdc.com, jiufei.xue@linux.alibaba.com Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org References: <20180728023058.GA21103@pjb1027-Latitude-E5410> <0f94623c-47e2-31e6-50ac-1d11ba061411@embeddedor.com> Message-ID: Date: Fri, 27 Jul 2018 21:56:38 -0500 MIME-Version: 1.0 In-Reply-To: <0f94623c-47e2-31e6-50ac-1d11ba061411@embeddedor.com> Content-Type: text/plain; charset=utf-8 List-ID: Jinbum, I just noticed this patch does not apply to linux-next. Please try again, but this time work from linux-next rather than from a stable tree. Thanks -- Gustavo On 07/27/2018 09:47 PM, Gustavo A. R. Silva wrote: > > > On 07/27/2018 09:30 PM, Jinbum Park wrote: >> User controls @dev_minor which to be used as index of pkt_devs. >> So, It can be exploited via Spectre-like attack. (speculative execution) >> >> This kind of attack leaks address of pkt_devs, [1] >> It leads an attacker to bypass security mechanism such as KASLR. >> >> So sanitize @dev_minor before using it to prevent attack. >> >> [1] https://github.com/jinb-park/linux-exploit/ >> tree/master/exploit-remaining-spectre-gadget/leak_pkt_devs.c >> >> Signed-off-by: Jinbum Park >> --- >> v2: Fix coding style by Gustavo. >> >> drivers/block/pktcdvd.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/block/pktcdvd.c b/drivers/block/pktcdvd.c >> index c61d20c..8ec2eaa 100644 >> --- a/drivers/block/pktcdvd.c >> +++ b/drivers/block/pktcdvd.c >> @@ -67,8 +67,8 @@ >> #include >> #include >> #include >> - >> #include >> +#include >> >> #define DRIVER_NAME "pktcdvd" >> >> @@ -2231,6 +2231,7 @@ static struct pktcdvd_device *pkt_find_dev_from_minor(unsigned int dev_minor) >> { >> if (dev_minor >= MAX_WRITERS) >> return NULL; >> + dev_minor = array_index_nospec(dev_minor, MAX_WRITERS); > > Adding a blank line here would be even better. > >> return pkt_devs[dev_minor]; >> } >> >> > > Acked-by: Gustavo A. R. Silva > > Thanks > -- > Gustavo >