Re: [PATCH 7/9] Guard bvec iteration logic v3

[Hannes Reinecke]

On 04/04/2017 08:56 PM, Dmitry Monakhov wrote:
> Currently if some one try to advance bvec beyond it's size we simply
> dump WARN_ONCE and continue to iterate beyond bvec array boundaries.
> This simply means that we endup dereferencing/corrupting random memory
> region.
> 
> Sane reaction would be to propagate error back to calling context
> But bvec_iter_advance's calling context is not always good for error
> handling. For safity reason let truncate iterator size to zero which
> will break external iteration loop which prevent us from unpredictable
> memory range corruption. And even it caller ignores an error, it will
> corrupt it's own bvecs, not others.
> 
> This patch does:
> - Return error back to caller with hope that it will react on this
> - Truncate iterator size
> 
> Code was added long time ago here 4550dd6c, luckily no one hit it
> in real life :)
> 
> changes since V1:
>  - Replace  BUG_ON with error logic.
> 
> Signed-off-by: Dmitry Monakhov <dmonakhov@xxxxxxxxxx>
> ---
>  drivers/nvdimm/blk.c |  4 +++-
>  drivers/nvdimm/btt.c |  4 +++-
>  include/linux/bio.h  |  8 ++++++--
>  include/linux/bvec.h | 11 ++++++++---
>  4 files changed, 20 insertions(+), 7 deletions(-)
> 
Reviewed-by: Hannes Reinecke <hare@xxxxxxxx>

Cheers,

Hannes
-- 
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