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AJvYcCWaypj9+9wSneVnRBeehVSyErPbQDBNCkyH5kr8dheeB4mazmH0ssvQqBnDmovhscVOk19ZfLxWFr7V4KU6S6+/FNo= X-Gm-Message-State: AOJu0YxlV6jiLicxA4EMEeig+IvnQZHH2DOkM/8G41Bys8Q5aCLVLhGk 2SLNSSpJKtrw42haFFcwNEq4VdowgAuvyXZQkILvpKWA+6/0p2AcqB2QvrFz9Wap5+x2hQKcSQE QPZlN8qU/Ki4CziR1C9IkAU6v8hNwSyOLZJRL X-Google-Smtp-Source: AGHT+IGLmcA5xxV1M4r6CbwNmSSM8fTDUc0WCfwWsdfAZHZjtPV8UqocY2ggpWtoUek+6I5ATI4LjP7xq1XesXiYQV0= X-Received: by 2002:a05:6402:35c3:b0:5a0:d4ce:59a6 with SMTP id 4fb4d7f45d1cf-5b45f835dbbmr100114a12.2.1722335470822; Tue, 30 Jul 2024 03:31:10 -0700 (PDT) MIME-Version: 1.0 References: <20240725-kasan-tsbrcu-v3-0-51c92f8f1101@google.com> <20240725-kasan-tsbrcu-v3-1-51c92f8f1101@google.com> In-Reply-To: From: Jann Horn Date: Tue, 30 Jul 2024 12:30:34 +0200 Message-ID: Subject: Re: [PATCH v3 1/2] kasan: catch invalid free before SLUB reinitializes the object To: Andrey Konovalov Cc: Andrey Ryabinin , Alexander Potapenko , Dmitry Vyukov , Vincenzo Frascino , Andrew Morton , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Vlastimil Babka , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, Marco Elver , kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Stat-Signature: odxrzcz83a3cm4kejfhsjcajoh87ak7i X-Rspamd-Queue-Id: CA1A2C0022 X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1722335472-815080 X-HE-Meta: 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 Xhn6vo/4 iMvL2aYnkI8PEYQ1D5/Atwn0Bz2uJ8PEPW5LheO2zfEMy84B70t6vIA6NGNm22+I8YhB8xNStCQdNvwZWB64aXtE/jk1iPHqA0oEZ22CekMIWxDn/EneSmPOcT5YFeCH/fHeSPBmUkh8N6RJU8KeHsA7YMHv6PvQYTWaIVl/OoKrfbs5v1Bf/xw/sURAbkCniL2b/2YEW/aywUJxEPc3SMWNZmDLA2nZu35Wp4w8qCCs08pks5d8VK4k798+0bm9Ugc/YutFmSmKM4jS+YfuPMXokV9ozR9zBdIzt 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: List-Subscribe: List-Unsubscribe: On Sat, Jul 27, 2024 at 2:47=E2=80=AFAM Andrey Konovalov wrote: > On Fri, Jul 26, 2024 at 3:52=E2=80=AFPM Jann Horn wrot= e: > > > > > Do we still need this patch? > > > > I just tried removing this patch from the series; without it, the > > kmem_cache_invalid_free kunit test fails because the kmem_cache_free() > > no longer synchronously notices that the pointer is misaligned. I > > guess I could change the testcase like this to make the tests pass > > without this patch, but I'd like to hear from you or another KASAN > > person whether you think that's a reasonable change: > > Ah, I see. I think detecting a bug earlier if we can is better. So I > don't mind keeping this patch, was just confused by the commit > message. ack, changed it in v4 > Adding on top of my comments from before: I think if you move > check_slab_free() out of poison_slab_object() (but add to > __kasan_mempool_poison_object()), and move is_kfence_address() and > kasan_arch_is_ready() to poison_slab_object()'s callers, you won't > even need the free_validation_result enum, so the patch should become > simpler. right, makes sense, changed in v4 > You can also rename check_slab_free() to check_slab_allocation() to > make it be named similarly to the already existing > check_page_allocation(). done in v4