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SubjectRe: [PATCH v5 net-next 00/12] bpf: rewrite value tracking in verifier
From: Daniel Borkmann <>
Date: Tue, 08 Aug 2017 02:46:16 +0200

> On 08/07/2017 04:21 PM, Edward Cree wrote:
>> This series simplifies alignment tracking, generalises bounds tracking
>> and
>> fixes some bounds-tracking bugs in the BPF verifier. Pointer
>> arithmetic on
>> packet pointers, stack pointers, map value pointers and context
>> pointers has
>> been unified, and bounds on these pointers are only checked when the
>> pointer
>> is dereferenced.
>> Operations on pointers which destroy all relation to the original
>> pointer
>> (such as multiplies and shifts) are disallowed if
>> !env->allow_ptr_leaks,
>> otherwise they convert the pointer to an unknown scalar and feed it to
>> the
>> normal scalar arithmetic handling.
>> Pointer types have been unified with the corresponding
>> adjusted-pointer types
>> where those existed (e.g. PTR_TO_MAP_VALUE[_ADJ] or FRAME_PTR vs
>> PTR_TO_STACK); similarly, CONST_IMM and UNKNOWN_VALUE have been
>> unified into
>> Pointer types (except CONST_PTR_TO_MAP, PTR_TO_MAP_VALUE_OR_NULL and
>> PTR_TO_PACKET_END, which do not allow arithmetic) have a 'fixed
>> offset' and
>> a 'variable offset'; the former is used when e.g. adding an immediate
>> or a
>> known-constant register, as long as it does not overflow. Otherwise
>> the
>> latter is used, and any operation creating a new variable offset
>> creates a
>> new 'id' (and, for PTR_TO_PACKET, clears the 'range').
>> SCALAR_VALUEs use the 'variable offset' fields to track the range of
>> possible
>> values; the 'fixed offset' should never be set on a scalar.
> Been testing and reviewing the series over the last several days,
> looks
> reasonable to me as far as I can tell. Thanks for all the hard work on
> unifying this, Edward!
> Acked-by: Daniel Borkmann <>

Series applied, thanks everyone!

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