lkml.org 
[lkml]   [2020]   [Sep]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] block: Fix potential NULL pointer dereference in __bio_crypt_clone()
On Wed, Sep 02, 2020 at 01:56:53AM +0000, linmiaohe wrote:
> Eric Biggers <ebiggers@kernel.org> wrote:
> >On Tue, Sep 01, 2020 at 07:59:21AM -0400, Miaohe Lin wrote:
> >> mempool_alloc() may return NULL if __GFP_DIRECT_RECLAIM is not set in
> >> gfp_mask under memory pressure. So we should check the return value of
> >> mempool_alloc() against NULL before dereference.
> >>
> >> Fixes: a892c8d52c02 ("block: Inline encryption support for blk-mq")
> >> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
> >
> >It's intended that __GFP_DIRECT_RECLAIM always be set here.
> >Do you have an example where it isn't set here?
>
> map_request() only pass GFP_ATOMIC to gfp_mask, though bio crypt is not used yet.
>
> >Also, if this can indeed happen, then we need to make __bio_crypt_clone() (and bio_crypt_clone()) return a bool (or an error code) to indicate whether it succeeded or failed. We can't just ignore the allocation failure.
> >
> >- Eric
>
> IMO, just the allocation failure is ok or we would break KABI.
> Many thanks.
>

Ignoring the allocation failure isn't okay, since it would cause encrypted I/O
to fall back to unencrypted I/O, which would cause data corruption.

Also, upstream doesn't have a stable KABI.

I sent out a patch with what I have in mind; can you take a look?
https://lkml.kernel.org/r/20200902051511.79821-1-ebiggers@kernel.org

- Eric

\
 
 \ /
  Last update: 2020-09-02 07:23    [W:0.035 / U:0.932 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site