[PATCH] net: filter: make JITs zero A for SKF_AD_ALU_XOR_X

[Eric Dumazet]

On Tue, 2016-01-05 at 16:23 +0100, Rabin Vincent wrote:
> The SKF_AD_ALU_XOR_X ancillary is not like the other ancillary data
> instructions since it XORs A with X while all the others replace A with
> some loaded value.  All the BPF JITs fail to clear A if this is used as
> the first instruction in a filter.

Is x86_64 part of this 'All' subset ? ;)

>   This was found using american fuzzy
> lop.
> 
> Add a helper to determine if A needs to be cleared given the first
> instruction in a filter, and use this in the JITs.  Except for ARM, the
> rest have only been compile-tested.
> 
> Fixes: 3480593131e0 ("net: filter: get rid of BPF_S_* enum")
> Signed-off-by: Rabin Vincent <rabin at rab.in>
> ---