Re: [PATCH v1 6/9] livepatch: Initial ARM64 support.

From: Julien Grall <julien.grall@arm.com>
To: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: xen-devel@lists.xenproject.org, ross.lagerwall@citrix.com,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	sstabellini@kernel.org
Subject: Re: [PATCH v1 6/9] livepatch: Initial ARM64 support.
Date: Wed, 17 Aug 2016 20:44:52 +0100	[thread overview]
Message-ID: <0869a371-cef7-5b06-1027-b98da7817a2b@arm.com> (raw)
In-Reply-To: <20160817015019.GA8704@localhost.localdomain>

On 17/08/2016 02:50, Konrad Rzeszutek Wilk wrote:
>>> +int arch_livepatch_perform_rela(struct livepatch_elf *elf,
>>> +                                const struct livepatch_elf_sec *base,
>>> +                                const struct livepatch_elf_sec *rela)
>>> +{
> .. snip..
>>> +        switch ( ELF64_R_TYPE(r->r_info) ) {
>>> +        /* Data */
>>> +        case R_AARCH64_ABS64:
>>> +            if ( r->r_offset + sizeof(uint64_t) > base->sec->sh_size )
>>> +                goto bad_offset;
>>
>> As you borrow the code from Linux, could we keep the abstraction with
>> reloc_data and defer the overflow check? It would avoid to have the same if
>> in multiple place in this code.
>
> The above 'if' conditional is a check to make sure that we don't
> go past the section (sh_size). In other words it is a boundary check to
> make sure the Elf file is not messed up.

Oh, Linux does not do those check. Sorry I though it was done. So I am 
fine with that.

Cheers,

-- 
Julien Grall

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