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b=AXGCPgWd4mydusswaGZKqx4kEvlENRvG/I3+tUFWa0XByeiLMpFRYIlajA9z/nRJr OlYuonufde9e5Fdl6T5Jf96rlSRlq5NLs/fKAvUS2+aIDY2nF+a4qvHLrT5ZwCgzld q4v4GbSKtg0dLAjab3P3ybv7nvWbSbKQ2XgDr0YM= Date: Thu, 4 Dec 2025 19:22:37 -0800 From: Andrew Morton To: Andrey Konovalov Cc: Maciej Wieczor-Retman , Andrey Ryabinin , Alexander Potapenko , Dmitry Vyukov , Vincenzo Frascino , Marco Elver , jiayuan.chen@linux.dev, stable@vger.kernel.org, Maciej Wieczor-Retman , kasan-dev@googlegroups.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 3/3] kasan: Unpoison vms[area] addresses with a common tag Message-Id: <20251204192237.0d7a07c9961843503c08ebab@linux-foundation.org> In-Reply-To: References: <873821114a9f722ffb5d6702b94782e902883fdf.1764874575.git.m.wieczorretman@pm.me> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Stat-Signature: 9g3yk16h3cprind3p8nmfyjh4on98f5i X-Rspam-User: X-Rspamd-Queue-Id: 57B51180008 X-Rspamd-Server: rspam09 X-HE-Tag: 1764904959-164144 X-HE-Meta: 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 uZbFApKo MSlEExKb+qKu4SaKXJqd9CvaxNxzcYR6e4l3IJwKkuhVwreUQ8zMEtfrvI40NECjXeYHsUastt7pWHhVVl8QrvnQOAEHrAJrRieNEu0SnfHcbKighUphoQWhZxloBKxotzBJ2VGTaLfdCvjlsLJmJu2+KgsAV9HwiPJHPcFlRHR5KsEDmwYBADAgRHSy+Xfi6Lg8zGJNUk7lnu4WZf5sEXL7dL5LRdtb2GxnnAFFApyIhIE04GQyOyzl7KaAvwvZAXp5RN6QTnn3LXgk1suNk1rHgUYVPh07M0zTj/AVXLf4CwwhfiqyG2YbVRIUPZKGezUuSsQ623mnr85GXm1s75spIsA== 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 Fri, 5 Dec 2025 02:09:06 +0100 Andrey Konovalov wrote: > > --- a/mm/kasan/common.c > > +++ b/mm/kasan/common.c > > @@ -591,11 +591,28 @@ void __kasan_unpoison_vmap_areas(struct vm_struct **vms, int nr_vms, > > unsigned long size; > > void *addr; > > int area; > > + u8 tag; > > + > > + /* > > + * If KASAN_VMALLOC_KEEP_TAG was set at this point, all vms[] pointers > > + * would be unpoisoned with the KASAN_TAG_KERNEL which would disable > > + * KASAN checks down the line. > > + */ > > + if (flags & KASAN_VMALLOC_KEEP_TAG) { > > I think we can do a WARN_ON() here: passing KASAN_VMALLOC_KEEP_TAG to > this function would be a bug in KASAN annotations and thus a kernel > bug. Therefore, printing a WARNING seems justified. This? --- a/mm/kasan/common.c~kasan-unpoison-vms-addresses-with-a-common-tag-fix +++ a/mm/kasan/common.c @@ -598,7 +598,7 @@ void __kasan_unpoison_vmap_areas(struct * would be unpoisoned with the KASAN_TAG_KERNEL which would disable * KASAN checks down the line. */ - if (flags & KASAN_VMALLOC_KEEP_TAG) { + if (WARN_ON_ONCE(flags & KASAN_VMALLOC_KEEP_TAG)) { pr_warn("KASAN_VMALLOC_KEEP_TAG flag shouldn't be already set!\n"); return; } _