Re: [PATCH v1 0/8] Fix set_huge_pte_at() panic on arm64

Andrew Morton
2023-09-21T21:13:08Z

On Thu, 21 Sep 2023 17:19:59 +0100 Ryan Roberts <ryan.roberts@arm.com> wrote:

> Hi All,
>
> This series fixes a bug in arm64's implementation of set_huge_pte_at(), which
> can result in an unprivileged user causing a kernel panic. The problem was
> triggered when running the new uffd poison mm selftest for HUGETLB memory. This
> test (and the uffd poison feature) was merged for v6.6-rc1. However, upon
> inspection there are multiple other pre-existing paths that can trigger this
> bug.
>
> Ideally, I'd like to get this fix in for v6.6 if possible? And I guess it should
> be backported too, given there are call sites where this can theoretically
> happen that pre-date v6.6-rc1 (I've cc'ed stable@vger.kernel.org).

This gets you a naggygram from Greg. The way to request a backport is
to add cc:stable to all the changelogs. I'll make that change to my copy.

> Ryan Roberts (8):
> parisc: hugetlb: Convert set_huge_pte_at() to take vma
> powerpc: hugetlb: Convert set_huge_pte_at() to take vma
> riscv: hugetlb: Convert set_huge_pte_at() to take vma
> s390: hugetlb: Convert set_huge_pte_at() to take vma
> sparc: hugetlb: Convert set_huge_pte_at() to take vma
> mm: hugetlb: Convert set_huge_pte_at() to take vma
> arm64: hugetlb: Convert set_huge_pte_at() to take vma
> arm64: hugetlb: Fix set_huge_pte_at() to work with all swap entries
>
> arch/arm64/include/asm/hugetlb.h | 2 +-
> arch/arm64/mm/hugetlbpage.c | 22 ++++----------
> arch/parisc/include/asm/hugetlb.h | 2 +-
> arch/parisc/mm/hugetlbpage.c | 4 +--
> .../include/asm/nohash/32/hugetlb-8xx.h | 3 +-
> arch/powerpc/mm/book3s64/hugetlbpage.c | 2 +-
> arch/powerpc/mm/book3s64/radix_hugetlbpage.c | 2 +-
> arch/powerpc/mm/nohash/8xx.c | 2 +-
> arch/powerpc/mm/pgtable.c | 7 ++++-
> arch/riscv/include/asm/hugetlb.h | 2 +-
> arch/riscv/mm/hugetlbpage.c | 3 +-
> arch/s390/include/asm/hugetlb.h | 8 +++--
> arch/s390/mm/hugetlbpage.c | 8 ++++-
> arch/sparc/include/asm/hugetlb.h | 8 +++--
> arch/sparc/mm/hugetlbpage.c | 8 ++++-
> include/asm-generic/hugetlb.h | 6 ++--
> include/linux/hugetlb.h | 6 ++--
> mm/damon/vaddr.c | 2 +-
> mm/hugetlb.c | 30 +++++++++----------
> mm/migrate.c | 2 +-
> mm/rmap.c | 10 +++----
> mm/vmalloc.c | 5 +++-
> 22 files changed, 80 insertions(+), 64 deletions(-)

Looks scary but it's actually a fairly modest patchset. It could
easily be all rolled into a single patch for ease of backporting.
Maybe Greg has an opinion?