linux-kernel - Re: [PATCH] block: fix a mismatched alloc free in bio_alloc

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Message-ID: <a7c09fbd-44a0-6541-ce1b-7fe03fcd43bf@acm.org>
Date:   Sun, 18 Aug 2019 09:26:43 -0700
From:   Bart Van Assche <bvanassche@....org>
To:     Pan Bian <bianpan2016@....com>, Jens Axboe <axboe@...nel.dk>
Cc:     linux-block@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] block: fix a mismatched alloc free in bio_alloc_bioset

On 8/18/19 3:57 AM, Pan Bian wrote:
> The function kmalloc is called to allocate memory if bs is NULL.
> However, mempool_free is used to release the memory chunk even if bs is
> NULL in the error hanlding code. This patch checks bs and use the
> correct function to release memory.
> 
> Signed-off-by: Pan Bian <bianpan2016@....com>
> ---
>   block/bio.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/block/bio.c b/block/bio.c
> index 299a0e7..c5f5238 100644
> --- a/block/bio.c
> +++ b/block/bio.c
> @@ -515,7 +515,10 @@ struct bio *bio_alloc_bioset(gfp_t gfp_mask, unsigned int nr_iovecs,
>   	return bio;
>   
>   err_free:
> -	mempool_free(p, &bs->bio_pool);
> +	if (!bs)
> +		kfree(p);
> +	else
> +		mempool_free(p, &bs->bio_pool);
>   	return NULL;
>   }
>   EXPORT_SYMBOL(bio_alloc_bioset);
> 

Please add "Fixes:" and "Cc: stable" tags. See also 
Documentation/process/submitting-patches.rst.

Thanks,

Bart.