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Mon, 19 Jan 2026 06:43:58 -0800 (PST) Message-ID: <38bcbe9c-5bc6-4bfa-b4ed-e187e048d600@gmail.com> Date: Mon, 19 Jan 2026 15:43:02 +0100 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/2] mm/kasan: Fix KASAN poisoning in vrealloc() To: Andrew Morton , Andrey Konovalov Cc: =?UTF-8?Q?Maciej_=C5=BBenczykowski?= , Maciej Wieczor-Retman , Alexander Potapenko , Dmitry Vyukov , Vincenzo Frascino , kasan-dev@googlegroups.com, Uladzislau Rezki , linux-kernel@vger.kernel.org, linux-mm@kvack.org, joonki.min@samsung-slsi.corp-partner.google.com, stable@vger.kernel.org References: <20260113191516.31015-1-ryabinin.a.a@gmail.com> <10812bb1-58c3-45c9-bae4-428ce2d8effd@gmail.com> <20260118164812.411f8f4f76e3a8aeec5d4704@linux-foundation.org> Content-Language: en-US From: Andrey Ryabinin In-Reply-To: <20260118164812.411f8f4f76e3a8aeec5d4704@linux-foundation.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 1/19/26 1:48 AM, Andrew Morton wrote: > On Sat, 17 Jan 2026 18:08:36 +0100 Andrey Konovalov wrote: > >> On Sat, Jan 17, 2026 at 2:16 AM Andrey Konovalov wrote: >>> >>> On Fri, Jan 16, 2026 at 2:26 PM Andrey Ryabinin wrote: >>>> >>>> So something like bellow I guess. >>> >>> Yeah, looks good. >>> >>>> I think this would actually have the opposite effect and make the code harder to follow. >>>> Introducing an extra wrapper adds another layer of indirection and more boilerplate, which >>>> makes the control flow less obvious and the code harder to navigate and grep. >>>> >>>> And what's the benefit here? I don't clearly see it. >>> >>> One functional benefit is when HW_TAGS mode enabled in .config but >>> disabled via command-line, we avoid a function call into KASAN >>> runtime. >> >> Ah, and I just realized than kasan_vrealloc should go into common.c - >> we also need it for HW_TAGS. > > I think I'll send this cc:stable bugfix upstream as-is. > Please, include follow-up fix before sending. We have to move kasan_vrealloc() to common.c as shadow.c is not compiled for CONFIG_KASAN_HW_TAGS=y. So without the fixup, CONFIG_KASAN_HW_TAGS=y will become broken.