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Mon, 26 Sep 2022 14:29:19 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id WKyXLT+3MWPNCgAAMHmgww (envelope-from ); Mon, 26 Sep 2022 14:29:19 +0000 Message-ID: <61bbbf65-9397-ac7d-9b57-2bfe5f0375ff@suse.cz> Date: Mon, 26 Sep 2022 16:29:19 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.3.0 Subject: Re: [PATCH v3] mm/slub: clean up create_unique_id() Content-Language: en-US To: Chao Yu , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Hugh Dickins Cc: Chao Yu , Christophe JAILLET , Hyeonggon Yoo <42.hyeyoo@gmail.com>, Roman Gushchin , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20220926142042.2725-1-chao@kernel.org> From: Vlastimil Babka In-Reply-To: <20220926142042.2725-1-chao@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 9/26/22 16:20, Chao Yu wrote: > From: Chao Yu > > 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; > } > " > > 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 > Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> > Signed-off-by: Chao Yu 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; > } >