From: Vlastimil Babka <vbabka@suse.cz>
To: Chao Yu <chao@kernel.org>, Christoph Lameter <cl@linux.com>,
Pekka Enberg <penberg@kernel.org>,
David Rientjes <rientjes@google.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Andrew Morton <akpm@linux-foundation.org>,
Hugh Dickins <hugh@veritas.com>
Cc: Chao Yu <chao.yu@oppo.com>,
Christophe JAILLET <christophe.jaillet@wanadoo.fr>,
Hyeonggon Yoo <42.hyeyoo@gmail.com>,
Roman Gushchin <roman.gushchin@linux.dev>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3] mm/slub: clean up create_unique_id()
Date: Mon, 26 Sep 2022 16:29:19 +0200 [thread overview]
Message-ID: <61bbbf65-9397-ac7d-9b57-2bfe5f0375ff@suse.cz> (raw)
In-Reply-To: <20220926142042.2725-1-chao@kernel.org>
On 9/26/22 16:20, Chao Yu wrote:
> From: Chao Yu <chao.yu@oppo.com>
>
> As Christophe JAILLET suggested:
>
> In create_unique_id(),
>
> "looks that ID_STR_LENGTH could even be reduced to 32 or 16.
>
> The 2nd BUG_ON at the end of the function could certainly be just
> removed as well or remplaced by a:
> if (p > name + ID_STR_LENGTH - 1) {
> kfree(name);
> return -E<something>;
> }
> "
>
> According to above suggestion, let's do below cleanups:
> 1. reduce ID_STR_LENGTH to 32, as the buffer size should be enough;
> 2. use WARN_ON instead of BUG_ON() and return error if check condition
> is true;
> 3. use snprintf instead of sprintf to avoid overflow.
>
> Link: https://lore.kernel.org/linux-mm/2025305d-16db-abdf-6cd3-1fb93371c2b4@wanadoo.fr/
> Fixes: 81819f0fc828 ("SLUB core")
> Suggested-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
> Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
> Signed-off-by: Chao Yu <chao.yu@oppo.com>
Thanks, added to slab.git for-next.
> ---
> v3:
> - clean up codes
> - fix size parameter of snprintf()
> mm/slub.c | 9 ++++++---
> 1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/mm/slub.c b/mm/slub.c
> index 4b98dff9be8e..4d3ee0924533 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -5890,7 +5890,7 @@ static inline struct kset *cache_kset(struct kmem_cache *s)
> return slab_kset;
> }
>
> -#define ID_STR_LENGTH 64
> +#define ID_STR_LENGTH 32
>
> /* Create a unique string id for a slab cache:
> *
> @@ -5924,9 +5924,12 @@ static char *create_unique_id(struct kmem_cache *s)
> *p++ = 'A';
> if (p != name + 1)
> *p++ = '-';
> - p += sprintf(p, "%07u", s->size);
> + p += snprintf(p, ID_STR_LENGTH - (p - name), "%07u", s->size);
>
> - BUG_ON(p > name + ID_STR_LENGTH - 1);
> + if (WARN_ON(p > name + ID_STR_LENGTH - 1)) {
> + kfree(name);
> + return ERR_PTR(-EINVAL);
> + }
> return name;
> }
>
prev parent reply other threads:[~2022-09-26 14:29 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-26 14:20 [PATCH v3] mm/slub: clean up create_unique_id() Chao Yu
2022-09-26 14:29 ` Vlastimil Babka [this message]
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