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From: "Håkon Bugge" <haakon.bugge@oracle.com>
To: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Leon Romanovsky <leon@kernel.org>,
	Peilin Ye <yepeilin.cs@gmail.com>,
	Santosh Shilimkar <santosh.shilimkar@oracle.com>,
	"David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	linux-kernel-mentees@lists.linuxfoundation.org,
	netdev@vger.kernel.org,
	OFED mailing list <linux-rdma@vger.kernel.org>,
	rds-devel@oss.oracle.com, linux-kernel@vger.kernel.org
Subject: Re: [Linux-kernel-mentees] [PATCH net] rds: Prevent kernel-infoleak in rds_notify_queue_get()
Date: Fri, 31 Jul 2020 13:14:09 +0200	[thread overview]
Message-ID: <81B40AF5-EBCA-4628-8CF6-687C12134552@oracle.com> (raw)
In-Reply-To: <20200731095943.GI5493@kadam>



> On 31 Jul 2020, at 11:59, Dan Carpenter <dan.carpenter@oracle.com> wrote:
> 
> On Fri, Jul 31, 2020 at 07:53:01AM +0300, Leon Romanovsky wrote:
>> On Thu, Jul 30, 2020 at 03:20:26PM -0400, Peilin Ye wrote:
>>> rds_notify_queue_get() is potentially copying uninitialized kernel stack
>>> memory to userspace since the compiler may leave a 4-byte hole at the end
>>> of `cmsg`.
>>> 
>>> In 2016 we tried to fix this issue by doing `= { 0 };` on `cmsg`, which
>>> unfortunately does not always initialize that 4-byte hole. Fix it by using
>>> memset() instead.
>> 
>> Of course, this is the difference between "{ 0 }" and "{}" initializations.
>> 
> 
> No, there is no difference.  Even struct assignments like:
> 
> 	foo = *bar;
> 
> can leave struct holes uninitialized.  Depending on the compiler the
> assignment can be implemented as a memset() or as a series of struct
> member assignments.

What about:

struct rds_rdma_notify {
	__u64                      user_token;
	__s32                      status;
} __attribute__((packed));


Thxs, Håkon


> regards,
> dan carpenter
> 


WARNING: multiple messages have this Message-ID (diff)
From: "Håkon Bugge" <haakon.bugge@oracle.com>
To: Dan Carpenter <dan.carpenter@oracle.com>
Cc: rds-devel@oss.oracle.com, Leon Romanovsky <leon@kernel.org>,
	Arnd Bergmann <arnd@arndb.de>,
	OFED mailing list <linux-rdma@vger.kernel.org>,
	Santosh Shilimkar <santosh.shilimkar@oracle.com>,
	linux-kernel@vger.kernel.org,
	"David S. Miller" <davem@davemloft.net>,
	netdev@vger.kernel.org, Jakub Kicinski <kuba@kernel.org>,
	linux-kernel-mentees@lists.linuxfoundation.org,
	Peilin Ye <yepeilin.cs@gmail.com>
Subject: Re: [Linux-kernel-mentees] [PATCH net] rds: Prevent kernel-infoleak in rds_notify_queue_get()
Date: Fri, 31 Jul 2020 13:14:09 +0200	[thread overview]
Message-ID: <81B40AF5-EBCA-4628-8CF6-687C12134552@oracle.com> (raw)
In-Reply-To: <20200731095943.GI5493@kadam>



> On 31 Jul 2020, at 11:59, Dan Carpenter <dan.carpenter@oracle.com> wrote:
> 
> On Fri, Jul 31, 2020 at 07:53:01AM +0300, Leon Romanovsky wrote:
>> On Thu, Jul 30, 2020 at 03:20:26PM -0400, Peilin Ye wrote:
>>> rds_notify_queue_get() is potentially copying uninitialized kernel stack
>>> memory to userspace since the compiler may leave a 4-byte hole at the end
>>> of `cmsg`.
>>> 
>>> In 2016 we tried to fix this issue by doing `= { 0 };` on `cmsg`, which
>>> unfortunately does not always initialize that 4-byte hole. Fix it by using
>>> memset() instead.
>> 
>> Of course, this is the difference between "{ 0 }" and "{}" initializations.
>> 
> 
> No, there is no difference.  Even struct assignments like:
> 
> 	foo = *bar;
> 
> can leave struct holes uninitialized.  Depending on the compiler the
> assignment can be implemented as a memset() or as a series of struct
> member assignments.

What about:

struct rds_rdma_notify {
	__u64                      user_token;
	__s32                      status;
} __attribute__((packed));


Thxs, Håkon


> regards,
> dan carpenter
> 

_______________________________________________
Linux-kernel-mentees mailing list
Linux-kernel-mentees@lists.linuxfoundation.org
https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees

  reply	other threads:[~2020-07-31 11:14 UTC|newest]

Thread overview: 62+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-30 19:20 [Linux-kernel-mentees] [PATCH net] rds: Prevent kernel-infoleak in rds_notify_queue_get() Peilin Ye
2020-07-30 19:20 ` Peilin Ye
2020-07-30 19:29 ` santosh.shilimkar
2020-07-30 19:29   ` santosh.shilimkar
2020-07-31  4:53 ` Leon Romanovsky
2020-07-31  4:53   ` Leon Romanovsky
2020-07-31  5:33   ` Greg Kroah-Hartman
2020-07-31  5:33     ` Greg Kroah-Hartman
2020-07-31  5:33     ` Greg Kroah-Hartman
2020-07-31  5:33       ` Greg Kroah-Hartman
2020-07-31  6:29       ` Andy Shevchenko
2020-07-31  7:00         ` Leon Romanovsky
2020-07-31  7:00           ` Leon Romanovsky
2020-07-31  7:05           ` Andy Shevchenko
2020-07-31  7:05             ` Andy Shevchenko
2020-07-31 14:04       ` Jason Gunthorpe
2020-07-31 14:04         ` Jason Gunthorpe
2020-07-31 14:21         ` Greg Kroah-Hartman
2020-07-31 14:21           ` Greg Kroah-Hartman
2020-07-31 14:36           ` Jason Gunthorpe
2020-07-31 14:36             ` Jason Gunthorpe
2020-07-31 17:19             ` Greg Kroah-Hartman
2020-07-31 17:19               ` Greg Kroah-Hartman
2020-07-31 18:27               ` Jason Gunthorpe
2020-07-31 18:27                 ` Jason Gunthorpe
2020-08-01  8:00                 ` Dan Carpenter
2020-08-01  8:00                   ` Dan Carpenter
2020-08-01 14:40                   ` Jason Gunthorpe
2020-08-01 14:40                     ` Jason Gunthorpe
2020-08-03  9:34                     ` Dan Carpenter
2020-08-03  9:34                       ` Dan Carpenter
2020-08-01  5:38               ` Leon Romanovsky
2020-08-01  5:38                 ` Leon Romanovsky
2020-08-02 22:10                 ` Jason Gunthorpe
2020-08-02 22:10                   ` Jason Gunthorpe
2020-08-02 22:23                   ` Joe Perches
2020-08-02 22:23                     ` Joe Perches
2020-08-02 22:28                     ` Jason Gunthorpe
2020-08-02 22:28                       ` Jason Gunthorpe
2020-08-02 22:45                       ` Joe Perches
2020-08-02 22:45                         ` Joe Perches
2020-08-03  4:58                         ` Leon Romanovsky
2020-08-03  4:58                           ` Leon Romanovsky
2020-08-03 23:06                         ` Jason Gunthorpe
2020-08-03 23:06                           ` Jason Gunthorpe
2020-08-08 22:57                           ` Jack Leadford
2020-08-08 22:57                             ` Jack Leadford
2020-08-09  7:04                             ` Leon Romanovsky
2020-08-09  7:04                               ` Leon Romanovsky
2020-08-14 17:07                             ` Jason Gunthorpe
2020-08-14 17:07                               ` Jason Gunthorpe
2020-07-31  6:31   ` Andy Shevchenko
2020-07-31  9:59   ` Dan Carpenter
2020-07-31  9:59     ` Dan Carpenter
2020-07-31 11:14     ` Håkon Bugge [this message]
2020-07-31 11:14       ` Håkon Bugge
2020-07-31 11:59       ` Greg Kroah-Hartman
2020-07-31 11:59         ` Greg Kroah-Hartman
2020-07-31 12:03         ` Håkon Bugge
2020-07-31 12:03           ` Håkon Bugge
2020-07-31 23:54 ` David Miller
2020-07-31 23:54   ` David Miller

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