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Re: [PATCH] sctp: use GFP_USER for user-controlled kmalloc

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On 12/01/2015 11:46 AM, David Laight wrote:
> From: Marcelo Ricardo Leitner
>> Sent: 30 November 2015 16:33
>> Dmitry Vyukov reported that the user could trigger a kernel warning by
>> using a large len value for getsockopt SCTP_GET_LOCAL_ADDRS, as that
>> value directly affects the value used as a kmalloc() parameter.
>>
>> This patch thus switches the allocation flags from all user-controllable
>> kmalloc size to GFP_USER to put some more restrictions on it and also
>> disables the warn, as they are not necessary.
>
> ISTM that the code should put some 'sanity limit' on that
> size before allocating the kernel buffer.

One could do that in addition, but this buffer has just a short lifetime
and by using GFP_USER hardwall restrictions apply already.
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[PATCH] sctp: use GFP_USER for user-controlled kmalloc Marcelo Ricardo Leitner <marcelo.leitner@gmail.com> - 2015-11-30 17:40 +0100
  RE: [PATCH] sctp: use GFP_USER for user-controlled kmalloc David Laight <David.Laight@ACULAB.COM> - 2015-12-01 11:50 +0100
    Re: [PATCH] sctp: use GFP_USER for user-controlled kmalloc Daniel Borkmann <daniel@iogearbox.net> - 2015-12-01 12:30 +0100
  Re: [PATCH] sctp: use GFP_USER for user-controlled kmalloc David Miller <davem@davemloft.net> - 2015-12-03 05:50 +0100

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