[PATCH v2 net] nfc: use GFP_USER for user-controlled kmalloc

[PATCH v2 net] nfc: use GFP_USER for user-controlled kmalloc

[Cong Wang]

These two functions are called in sendmsg path, and the
'len' is passed from user-space, so we should not allow
malicious users to OOM kernel on purpose.

Reported-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Lauro Ramos Venancio <lauro.venancio@openbossa.org>
Cc: Aloisio Almeida Jr <aloisio.almeida@openbossa.org>
Cc: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
---
 net/nfc/llcp_commands.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/nfc/llcp_commands.c b/net/nfc/llcp_commands.c
index 3621a90..3425532 100644
--- a/net/nfc/llcp_commands.c
+++ b/net/nfc/llcp_commands.c
@@ -663,7 +663,7 @@ int nfc_llcp_send_i_frame(struct nfc_llcp_sock *sock,
 		return -ENOBUFS;
 	}
 
-	msg_data = kzalloc(len, GFP_KERNEL);
+	msg_data = kmalloc(len, GFP_USER | __GFP_NOWARN);
 	if (msg_data == NULL)
 		return -ENOMEM;
 
@@ -729,7 +729,7 @@ int nfc_llcp_send_ui_frame(struct nfc_llcp_sock *sock, u8 ssap, u8 dsap,
 	if (local == NULL)
 		return -ENODEV;
 
-	msg_data = kzalloc(len, GFP_KERNEL);
+	msg_data = kmalloc(len, GFP_USER | __GFP_NOWARN);
 	if (msg_data == NULL)
 		return -ENOMEM;
 
-- 
1.8.3.1

Re: [PATCH v2 net] nfc: use GFP_USER for user-controlled kmalloc

[Eric Dumazet]

On Fri, 2016-01-29 at 11:24 -0800, Cong Wang wrote:
> These two functions are called in sendmsg path, and the
> 'len' is passed from user-space, so we should not allow
> malicious users to OOM kernel on purpose.
> 
> Reported-by: Dmitry Vyukov <dvyukov@google.com>
> Cc: Lauro Ramos Venancio <lauro.venancio@openbossa.org>
> Cc: Aloisio Almeida Jr <aloisio.almeida@openbossa.org>
> Cc: Samuel Ortiz <sameo@linux.intel.com>
> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
> ---

Note that the issue is not OOM the kernel (as the allocation is
attempted even after your patch), but having a way to
spill stack traces in the syslog.

Acked-by: Eric Dumazet <edumazet@google.com>

Thanks!

Re: [PATCH v2 net] nfc: use GFP_USER for user-controlled kmalloc

[Julian Calaby]

Hi Cong

On Sat, Jan 30, 2016 at 6:46 AM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
> On Fri, 2016-01-29 at 11:24 -0800, Cong Wang wrote:
>> These two functions are called in sendmsg path, and the
>> 'len' is passed from user-space, so we should not allow
>> malicious users to OOM kernel on purpose.
>>
>> Reported-by: Dmitry Vyukov <dvyukov@google.com>
>> Cc: Lauro Ramos Venancio <lauro.venancio@openbossa.org>
>> Cc: Aloisio Almeida Jr <aloisio.almeida@openbossa.org>
>> Cc: Samuel Ortiz <sameo@linux.intel.com>
>> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
>> ---
>
> Note that the issue is not OOM the kernel (as the allocation is
> attempted even after your patch), but having a way to
> spill stack traces in the syslog.
>
> Acked-by: Eric Dumazet <edumazet@google.com>

Reviewed-by: Julian Calaby <julian.calaby@gmail.com>

Thanks,

-- 
Julian Calaby

Email: julian.calaby@gmail.com
Profile: http://www.google.com/profiles/julian.calaby/

Re: [PATCH v2 net] nfc: use GFP_USER for user-controlled kmalloc

[Cong Wang]

On Fri, Jan 29, 2016 at 11:24 AM, Cong Wang <xiyou.wangcong@gmail.com> wrote:
> These two functions are called in sendmsg path, and the
> 'len' is passed from user-space, so we should not allow
> malicious users to OOM kernel on purpose.
>
> Reported-by: Dmitry Vyukov <dvyukov@google.com>
> Cc: Lauro Ramos Venancio <lauro.venancio@openbossa.org>
> Cc: Aloisio Almeida Jr <aloisio.almeida@openbossa.org>
> Cc: Samuel Ortiz <sameo@linux.intel.com>
> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>

Ping...

David, this patch seems still not applied, I guess you expect NFC
maintainer to take it, but this doesn't happen. Could you take it?

(I can resend it if you need.)

Thanks!

> ---
>  net/nfc/llcp_commands.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/net/nfc/llcp_commands.c b/net/nfc/llcp_commands.c
> index 3621a90..3425532 100644
> --- a/net/nfc/llcp_commands.c
> +++ b/net/nfc/llcp_commands.c
> @@ -663,7 +663,7 @@ int nfc_llcp_send_i_frame(struct nfc_llcp_sock *sock,
>                 return -ENOBUFS;
>         }
>
> -       msg_data = kzalloc(len, GFP_KERNEL);
> +       msg_data = kmalloc(len, GFP_USER | __GFP_NOWARN);
>         if (msg_data == NULL)
>                 return -ENOMEM;
>
> @@ -729,7 +729,7 @@ int nfc_llcp_send_ui_frame(struct nfc_llcp_sock *sock, u8 ssap, u8 dsap,
>         if (local == NULL)
>                 return -ENODEV;
>
> -       msg_data = kzalloc(len, GFP_KERNEL);
> +       msg_data = kmalloc(len, GFP_USER | __GFP_NOWARN);
>         if (msg_data == NULL)
>                 return -ENOMEM;
>
> --
> 1.8.3.1
>

Re: [PATCH v2 net] nfc: use GFP_USER for user-controlled kmalloc

[David Miller]

From: Cong Wang <xiyou.wangcong@gmail.com>
Date: Wed, 24 Feb 2016 10:41:29 -0800

> On Fri, Jan 29, 2016 at 11:24 AM, Cong Wang <xiyou.wangcong@gmail.com> wrote:
>> These two functions are called in sendmsg path, and the
>> 'len' is passed from user-space, so we should not allow
>> malicious users to OOM kernel on purpose.
>>
>> Reported-by: Dmitry Vyukov <dvyukov@google.com>
>> Cc: Lauro Ramos Venancio <lauro.venancio@openbossa.org>
>> Cc: Aloisio Almeida Jr <aloisio.almeida@openbossa.org>
>> Cc: Samuel Ortiz <sameo@linux.intel.com>
>> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
> 
> Ping...
> 
> David, this patch seems still not applied, I guess you expect NFC
> maintainer to take it, but this doesn't happen. Could you take it?

The NFC maintainer needs to take this, ping them explicitly if
you have to.

Thanks.

Re: [PATCH v2 net] nfc: use GFP_USER for user-controlled kmalloc

[Cong Wang]

On Wed, Feb 24, 2016 at 10:45 AM, David Miller <davem@davemloft.net> wrote:
> From: Cong Wang <xiyou.wangcong@gmail.com>
> Date: Wed, 24 Feb 2016 10:41:29 -0800
>
>> On Fri, Jan 29, 2016 at 11:24 AM, Cong Wang <xiyou.wangcong@gmail.com> wrote:
>>> These two functions are called in sendmsg path, and the
>>> 'len' is passed from user-space, so we should not allow
>>> malicious users to OOM kernel on purpose.
>>>
>>> Reported-by: Dmitry Vyukov <dvyukov@google.com>
>>> Cc: Lauro Ramos Venancio <lauro.venancio@openbossa.org>
>>> Cc: Aloisio Almeida Jr <aloisio.almeida@openbossa.org>
>>> Cc: Samuel Ortiz <sameo@linux.intel.com>
>>> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
>>
>> Ping...
>>
>> David, this patch seems still not applied, I guess you expect NFC
>> maintainer to take it, but this doesn't happen. Could you take it?
>
> The NFC maintainer needs to take this, ping them explicitly if
> you have to.

OK. I think Samuel is looking at it now.

Thanks!

Re: [PATCH v2 net] nfc: use GFP_USER for user-controlled kmalloc

[Samuel Ortiz]

On Wed, Feb 24, 2016 at 10:41:29AM -0800, Cong Wang wrote:
> On Fri, Jan 29, 2016 at 11:24 AM, Cong Wang <xiyou.wangcong@gmail.com> wrote:
> > These two functions are called in sendmsg path, and the
> > 'len' is passed from user-space, so we should not allow
> > malicious users to OOM kernel on purpose.
> >
> > Reported-by: Dmitry Vyukov <dvyukov@google.com>
> > Cc: Lauro Ramos Venancio <lauro.venancio@openbossa.org>
> > Cc: Aloisio Almeida Jr <aloisio.almeida@openbossa.org>
> > Cc: Samuel Ortiz <sameo@linux.intel.com>
> > Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
> 
> Ping...
> 
> David, this patch seems still not applied, I guess you expect NFC
> maintainer to take it, but this doesn't happen. Could you take it?
I'll look at it later today.

Cheers,
Samuel.

Re: [PATCH v2 net] nfc: use GFP_USER for user-controlled kmalloc

[Samuel Ortiz]

Hi Cong,

On Fri, Jan 29, 2016 at 11:24:24AM -0800, Cong Wang wrote:
> These two functions are called in sendmsg path, and the
> 'len' is passed from user-space, so we should not allow
> malicious users to OOM kernel on purpose.
> 
> Reported-by: Dmitry Vyukov <dvyukov@google.com>
> Cc: Lauro Ramos Venancio <lauro.venancio@openbossa.org>
> Cc: Aloisio Almeida Jr <aloisio.almeida@openbossa.org>
> Cc: Samuel Ortiz <sameo@linux.intel.com>
> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
> ---
>  net/nfc/llcp_commands.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
Applied to nfc-next, thanks.

Cheers,
Samuel.