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SubjectRe: [PATCH] block: fix memory leak in bio_clone()
On Mon, Mar 09 2009, Li Zefan wrote:
> If bio_integrity_clone() fails, bio_clone() returns NULL without freeing
> the newly allocated bio.
>
> Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
> ---
> fs/bio.c | 4 +++-
> 1 files changed, 3 insertions(+), 1 deletions(-)
>
> diff --git a/fs/bio.c b/fs/bio.c
> index 124b95c..896330e 100644
> --- a/fs/bio.c
> +++ b/fs/bio.c
> @@ -465,8 +465,10 @@ struct bio *bio_clone(struct bio *bio, gfp_t gfp_mask)
>
> ret = bio_integrity_clone(b, bio, fs_bio_set);
>
> - if (ret < 0)
> + if (ret < 0) {
> + bio_put(bio);
> return NULL;
> + }
> }
>
> return b;
> -- 1.5.4.rc3

Good spotting. But it looks like there are actually several problems
there. bio_integrity_clone() is mempool backed. Currently that ret < 0
can never trigger, since bio_integrity_clone() has hard-wired __GFP_WAIT
as the mempool mask. So the leak will not occur, but it does mean that
it isn't honoring the gfp_mask passed in to bio_clone(), which is the
first bug. The second bug is that it should be using its own bioset, as
it is illegal to do multiple __GFP_WAIT allocations on a single mempool
and always expect progress.

--
Jens Axboe



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