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b=JG+gPzUHCApSyS7KTNybCh1RpLBktz6oIyaZDWmOi0SQTnhEjoEI6jCdpVpLGBcYJ YlzbQgJK8V9CUmLTiCUoKNVE/vnqM4spBQrykU7mgr5rgO6FgT6zixT+YFzhKYd2nz 4HgP7gFqa4WQQ3EuAbsbFr7vbbiAE0NkXRYU7mOhrK0vljIyofpvoBDSAbjka24F/v +qCIj+3bl4hbrsXbjzgl3RXAMnPR+nglLhWpRPApW4zmOTRweXuUn32TnAuoNatI5+ TKt06gOrLyoGLh246TWxskSpPmyRboN3kf2+iVja9ngB8CpBKzTuKocPOoPzhwn8bZ YGh572WwZ8u6A== Message-ID: Date: Thu, 2 Jul 2026 17:47:21 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 6/6] mm/mprotect: use huge_ptep_get() for hugetlb To: Dev Jain , muchun.song@linux.dev, osalvador@suse.de, akpm@linux-foundation.org, ljs@kernel.org, liam@infradead.org Cc: riel@surriel.com, vbabka@kernel.org, harry@kernel.org, jannh@google.com, lance.yang@linux.dev, kas@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, rcampbell@nvidia.com, apopple@nvidia.com, ziy@nvidia.com, matthew.brost@intel.com, joshua.hahnjy@gmail.com, rakie.kim@sk.com, byungchul@sk.com, gourry@gourry.net, ying.huang@linux.alibaba.com, j-nomura@ce.jp.nec.com, nao.horiguchi@gmail.com, ak@linux.intel.com, mel@csn.ul.ie, pfalcato@suse.de, jpoimboe@kernel.org, dave.hansen@intel.com, tglx@kernel.org, catalin.marinas@arm.com, will@kernel.org, linux-arm-kernel@lists.infradead.org, ryan.roberts@arm.com, anshuman.khandual@arm.com References: <20260702051341.126509-1-dev.jain@arm.com> <20260702051341.126509-7-dev.jain@arm.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam11 X-Rspam-User: X-Stat-Signature: ygkbdw14exp5rqwugdmm49k1qetc5pyx X-Rspamd-Queue-Id: 76C8F80005 X-HE-Tag: 1783007252-630555 X-HE-Meta: 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 T87IZ97P huGFCx1inlXpnMqnXu9M8Fy2z82yM2kvK9gsABBfcQ6mvRSdqfKeu7QDmfrkXITDYjdBndEK8/BTMB6pE8Y+3FtCT665ge09lFwOHUkRjJCKDNGRu9YaslPvxfWPCJYyvsztVyws04ueAuUGKyYr658X1vSSfQrTUAQLxizVye+cTw0rFPYRuzyIWwS27JTkzfUc7KmyKliFzQa6VRirV4xP8BiWkhRFaMkpnmlByjUifEzSs9LCAG+aVmNmHkPPVN+k51p/wzIzwc9XYdmB/utSJwFBluxitpkoasqE/sju35LBfue6MK+5YOTt9WdGom2ldqSjSHU//ueAwAAbCA2D+EE7tYqTbzljQsvSLkL17ISt4PnkrFwkE07MzMfwiISfgF9QlZXKWf+axfhwGPGasTpBSvroeSut+cVozSlI+C+bF9IE3VIfEkFDQRfDB+cWo Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 7/2/26 07:13, Dev Jain wrote: > prot_none_hugetlb_entry() is the hugetlb callback for the early > mprotect(PROT_NONE) PFN permission walk on x86. > > The callback passes the decoded PFN to pfn_modify_allowed(). For a > hugetlb callback, the pte pointer refers to a hugetlb entry. On > architectures where hugetlb entries need huge_ptep_get(), reading that > entry with ptep_get() can make the permission check use the wrong PFN. > > Use huge_ptep_get() before decoding the hugetlb PFN. > > Currently there is no path which can trigger a bug: huge_ptep_get() is a > simple ptep_get() for x86, and the prot_none walk occurs only for x86. > > So no need to backport - use the correct helper anyways. > > Fixes: 42e4089c7890 ("x86/speculation/l1tf: Disallow non privileged high MMIO PROT_NONE mappings") > Signed-off-by: Dev Jain > --- > mm/mprotect.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/mm/mprotect.c b/mm/mprotect.c > index 9cbf932b028cf..23779632d18bf 100644 > --- a/mm/mprotect.c > +++ b/mm/mprotect.c > @@ -699,14 +699,20 @@ static int prot_none_pte_entry(pte_t *pte, unsigned long addr, > 0 : -EACCES; > } > > +#ifdef CONFIG_HUGETLB_PAGE > static int prot_none_hugetlb_entry(pte_t *pte, unsigned long hmask, > unsigned long addr, unsigned long next, > struct mm_walk *walk) > { > - return pfn_modify_allowed(pte_pfn(ptep_get(pte)), > + pte_t entry = huge_ptep_get(walk->mm, addr, pte); Nit: can be const :) > + > + return pfn_modify_allowed(pte_pfn(entry), > *(pgprot_t *)(walk->private)) ? > 0 : -EACCES; Indentation is odd. Can we just make this readable? if (pfn_modify_allowed ...) return 0 return -EACCESS; -- Cheers, David