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Tue, 23 Aug 2022 20:52:39 -0700 (PDT) Date: Wed, 24 Aug 2022 12:52:34 +0900 From: Hyeonggon Yoo <42.hyeyoo@gmail.com> To: Vlastimil Babka Cc: Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Roman Gushchin , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Marco Elver Subject: Re: [PATCH v4 17/17] mm/sl[au]b: check if large object is valid in __ksize() Message-ID: References: <20220817101826.236819-1-42.hyeyoo@gmail.com> <20220817101826.236819-18-42.hyeyoo@gmail.com> <66e25026-a86a-0157-3671-cf66eb53964c@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <66e25026-a86a-0157-3671-cf66eb53964c@suse.cz> ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1661313162; a=rsa-sha256; cv=none; b=qArh8al16Z5fke5XkFYOIJj/1JADUpi7fZycNr5CnakbY9JtdqSFBCgu0R0Rn9Om6TO+4b Els1uNJLJzjovz7Vbrpe3l8vcRYiT+wzet4gxVLx+N/lNsPmp/YXnX0R8N0LZ22o+QOnJj 9hDwU7uvGYhrizh3mj+Av/RX2fu/tDE= ARC-Authentication-Results: i=1; imf15.hostedemail.com; 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dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf15.hostedemail.com: domain of 42.hyeyoo@gmail.com designates 209.85.210.175 as permitted sender) smtp.mailfrom=42.hyeyoo@gmail.com X-Stat-Signature: maeibat1ctjwghoc6no1ki4jf9fuwmwz X-HE-Tag: 1661313161-114775 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Aug 23, 2022 at 05:12:01PM +0200, Vlastimil Babka wrote: > On 8/17/22 12:18, Hyeonggon Yoo wrote: > > If address of large object is not beginning of folio or size of > > the folio is too small, it must be invalid. BUG() in such cases. > > > > Cc: Marco Elver > > Suggested-by: Vlastimil Babka > > Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> > > Reviewed-by: Vlastimil Babka > > --- > > mm/slab_common.c | 5 ++++- > > 1 file changed, 4 insertions(+), 1 deletion(-) > > > > diff --git a/mm/slab_common.c b/mm/slab_common.c > > index 9c273a5fb0d7..98d029212682 100644 > > --- a/mm/slab_common.c > > +++ b/mm/slab_common.c > > @@ -984,8 +984,11 @@ size_t __ksize(const void *object) > > > > folio = virt_to_folio(object); > > > > - if (unlikely(!folio_test_slab(folio))) > > + if (unlikely(!folio_test_slab(folio))) { > > + BUG_ON(folio_size(folio) <= KMALLOC_MAX_CACHE_SIZE); > > + BUG_ON(object != folio_address(folio)); > > return folio_size(folio); > > + } > > > > return slab_ksize(folio_slab(folio)->slab_cache); > > } > > In light of latest Linus' rant on BUG_ON() [1] I'm changing it to WARN_ON > and return 0, as it was in v3. > > [1] https://lore.kernel.org/all/CAHk-=wiEAH+ojSpAgx_Ep=NKPWHU8AdO3V56BXcCsU97oYJ1EA@mail.gmail.com/ Okay. I'm fine with that. > > > diff --git a/mm/slab_common.c b/mm/slab_common.c > index 98d029212682..a80c3a5e194d 100644 > --- a/mm/slab_common.c > +++ b/mm/slab_common.c > @@ -985,8 +985,10 @@ size_t __ksize(const void *object) > folio = virt_to_folio(object); > > if (unlikely(!folio_test_slab(folio))) { > - BUG_ON(folio_size(folio) <= KMALLOC_MAX_CACHE_SIZE); > - BUG_ON(object != folio_address(folio)); > + if (WARN_ON(folio_size(folio) <= KMALLOC_MAX_CACHE_SIZE)) > + return 0; > + if (WARN_ON(object != folio_address(folio))) > + return 0; > return folio_size(folio); > } > > -- Thanks, Hyeonggon