linux-kernel - Re: [PATCH 1/2] mm: mmap: fix fput in error path v2

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Message-ID: <20201016161310.GE36674@ziepe.ca>
Date:   Fri, 16 Oct 2020 13:13:10 -0300
From:   Jason Gunthorpe <jgg@...pe.ca>
To:     Christian König <ckoenig.leichtzumerken@...il.com>
Cc:     akpm@...ux-foundation.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, linaro-mm-sig@...ts.linaro.org,
        dri-devel@...ts.freedesktop.org, linux-media@...r.kernel.org,
        chris@...is-wilson.co.uk, airlied@...hat.com, daniel@...ll.ch,
        sumit.semwal@...aro.org, willy@...radead.org, jhubbard@...dia.com,
        linmiaohe@...wei.com
Subject: Re: [PATCH 1/2] mm: mmap: fix fput in error path v2

On Mon, Oct 12, 2020 at 10:52:02AM +0200, Christian König wrote:
> Patch "495c10cc1c0c CHROMIUM: dma-buf: restore args..."
> adds a workaround for a bug in mmap_region.
> 
> As the comment states ->mmap() callback can change
> vma->vm_file and so we might call fput() on the wrong file.
> 
> Revert the workaround and proper fix this in mmap_region.
> 
> v2: drop the extra if in dma_buf_mmap as well
> 
> Signed-off-by: Christian König <christian.koenig@....com>
> Reviewed-by: Jason Gunthorpe <jgg@...dia.com>
> ---
>  drivers/dma-buf/dma-buf.c | 20 +++-----------------
>  mm/mmap.c                 |  2 +-
>  2 files changed, 4 insertions(+), 18 deletions(-)

Reviewed-by: Jason Gunthorpe <jgg@...dia.com>

Probably should Fixes that other patch Andrew pointed at

Jason