From: "David Hildenbrand (Arm)" <david@kernel.org>
To: Dev Jain <dev.jain@arm.com>,
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,
apopple@nvidia.com, rcampbell@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, ak@linux.intel.com,
nao.horiguchi@gmail.com, mel@csn.ul.ie, j-nomura@ce.jp.nec.com,
pfalcato@suse.de, tglx@kernel.org, dave.hansen@intel.com,
jpoimboe@kernel.org, catalin.marinas@arm.com, will@kernel.org,
linux-arm-kernel@lists.infradead.org, ryan.roberts@arm.com,
anshuman.khandual@arm.com
Subject: Re: [PATCH v3 6/6] mm/mprotect: use huge_ptep_get() for hugetlb
Date: Mon, 6 Jul 2026 10:48:21 +0200 [thread overview]
Message-ID: <41f08ccd-39dd-4b69-8ddf-60da848fef6a@kernel.org> (raw)
In-Reply-To: <20260703114202.365553-7-dev.jain@arm.com>
On 7/3/26 13:41, 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")
> Reviewed-by: Muchun Song <muchun.song@linux.dev>
> Signed-off-by: Dev Jain <dev.jain@arm.com>
> ---
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
--
Cheers,
David
next prev parent reply other threads:[~2026-07-06 8:48 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-03 11:41 [PATCH v3 0/6] Fix incorrect access of hugetlb pte entries Dev Jain
2026-07-03 11:41 ` [PATCH v3 1/6] arm64: make huge_ptep_get handled unaligned addresses Dev Jain
2026-07-04 2:42 ` Muchun Song
2026-07-05 7:35 ` Andrew Morton
2026-07-05 8:08 ` Dev Jain
2026-07-06 8:45 ` David Hildenbrand (Arm)
2026-07-06 10:52 ` Dev Jain
2026-07-06 10:54 ` Dev Jain
2026-07-06 14:04 ` David Hildenbrand (Arm)
2026-07-03 11:41 ` [PATCH v3 2/6] mm/rmap: use huge_ptep_get() in try_to_unmap_one() Dev Jain
2026-07-04 2:44 ` Muchun Song
2026-07-06 8:46 ` David Hildenbrand (Arm)
2026-07-03 11:41 ` [PATCH v3 3/6] mm/rmap: use huge_ptep_get() in try_to_migrate_one() Dev Jain
2026-07-06 8:46 ` David Hildenbrand (Arm)
2026-07-03 11:41 ` [PATCH v3 4/6] mm/migrate: use huge_ptep_get() in remove_migration_pte() Dev Jain
2026-07-03 11:41 ` [PATCH v3 5/6] mm/page_vma_mapped: use huge_ptep_get() for hugetlb Dev Jain
2026-07-03 11:41 ` [PATCH v3 6/6] mm/mprotect: " Dev Jain
2026-07-05 8:33 ` Andrew Morton
2026-07-05 8:47 ` Dev Jain
2026-07-06 8:48 ` David Hildenbrand (Arm) [this message]
2026-07-05 7:45 ` [PATCH v3 0/6] Fix incorrect access of hugetlb pte entries Andrew Morton
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