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dkim=pass (1024-bit key; unprotected) header.d=arm.com header.i=@arm.com header.a=rsa-sha256 header.s=foss header.b=P+jtgdTX; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=arm.com (client-ip=217.140.110.172; helo=foss.arm.com; envelope-from=dev.jain@arm.com; receiver=lists.ozlabs.org) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lists.ozlabs.org (Postfix) with ESMTP id 4jGC6R4qcBz30C6 for ; Fri, 30 Oct 2026 18:15:09 +1100 (AEDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 1101615A1; Fri, 30 Oct 2026 00:14:33 -0700 (PDT) Received: from [10.163.152.232] (unknown [10.163.152.232]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 8D0273F7B4; Fri, 30 Oct 2026 00:14:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1793344476; bh=Jp/eodRxYkJLNGQk8olzS9xG6qObIMTBg1q6BMVZmBI=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=P+jtgdTX69sEy90NVnhYUwff1Df/OdYgDe+/Oll2oU0iv4SgMtAerOkfvpkn4fqBX bHrTkw2g7dShto71IFHPDpjzFhRFcDPHxQhkGP7LbYYciMVEjNypabXr9lGoDG0b9P Dl6AC3L9oAHxYeXPdZCnniBAcCySVpa1QB2Dy4po= Message-ID: <99f529e8-06f7-4a20-a60b-0330c5d3d91c@arm.com> Date: Fri, 30 Oct 2026 12:44:26 +0530 X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , Precedence: list X-Archived-By: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 03/10] mm/vmalloc: clamp an unaligned range in vunmap_pte_range() To: Hao Ge , Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , "Christophe Leroy (CS GROUP)" , "Ritesh Harjani (IBM)" , Shrikanth Hegde , Alexander Potapenko , Marco Elver , Dmitry Vyukov , Andrew Morton , Dennis Zhou , Tejun Heo , Christoph Lameter , Uladzislau Rezki , Suren Baghdasaryan Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, linux-mm@kvack.org, Sashiko References: <20261026080329.140244-1-hao.ge@linux.dev> <20261026080329.140244-4-hao.ge@linux.dev> Content-Language: en-US From: Dev Jain In-Reply-To: <20261026080329.140244-4-hao.ge@linux.dev> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-17.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On 26/10/26 1:33 pm, Hao Ge wrote: > commit a739e6b557af ("mm: vmalloc: WARN_ON if mapping size is not > PAGE_SIZE aligned") made vmap_pte_range() warn and bail out when the > size is not a multiple of PAGE_SIZE. That loop steps in page Why are we checking the alignment so late into vmap_pte_range? Why not simply do if (!IS_ALIGNED(addr, PAGE_SIZE) || !IS_ALIGNED(end, PAGE_SIZE)) return; (or return -EINVAL); at the start of vmap_range_noflush and vunmap_range_noflush? > multiples and stops only at addr == end; with an unaligned size addr > never lands on end, so the loop cannot terminate and walks off the > end of the page table. > > vunmap_pte_range() has the same loop without any guard, so an > unaligned range would clear PTEs past end without ever stopping, > walking off the end of the page table. > > Add the check there too. The range is clamped down to the last full > page rather than dropped, and the loop is skipped when nothing is > left, so a buggy caller still gets its PTEs cleared as far as they > go. > > Reported-by: Sashiko > Signed-off-by: Hao Ge > --- > mm/vmalloc.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index 44e0eb32708f..7131f60d1a8e 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -393,6 +393,11 @@ static void vunmap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, > pte_t ptent; > unsigned long size = PAGE_SIZE; > > + if (WARN_ON_ONCE(!PAGE_ALIGNED(end - addr))) > + end = addr + PAGE_ALIGN_DOWN(end - addr); > + if (end == addr) > + return; > + > pte = pte_offset_kernel(pmd, addr); > lazy_mmu_mode_enable(); >