From: Ryan Roberts ryan.roberts@arm.com
mainline inclusion from mainline-6.7-rc2 commit afccb0804fc74ac2f6737af6a139632606cb461d category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I98AW9 CVE: NA
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Commit c33c794828f2 ("mm: ptep_get() conversion") converted all (non-arch) call sites to use ptep_get() instead of doing a direct dereference of the pte. Full rationale can be found in that commit's log.
Since then, three new call sites have snuck in, which directly dereference the pte, so let's fix those up.
Unfortunately there is no reliable automated mechanism to catch these; I'm relying on a combination of Coccinelle (which throws up a lot of false positives) and some compiler magic to force a compiler error on dereference (While this approach finds dereferences, it also yields a non-booting kernel so can't be committed).
Link: https://lkml.kernel.org/r/20231114154945.490401-1-ryan.roberts@arm.com Signed-off-by: Ryan Roberts ryan.roberts@arm.com Cc: Matthew Wilcox (Oracle) willy@infradead.org Signed-off-by: Andrew Morton akpm@linux-foundation.org (cherry picked from commit afccb0804fc74ac2f6737af6a139632606cb461d) Signed-off-by: Kefeng Wang wangkefeng.wang@huawei.com --- mm/filemap.c | 2 +- mm/ksm.c | 2 +- mm/userfaultfd.c | 2 +- 3 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/mm/filemap.c b/mm/filemap.c index da44ba00526f..d2aad2ff2892 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -3483,7 +3483,7 @@ static vm_fault_t filemap_map_folio_range(struct vm_fault *vmf, * handled in the specific fault path, and it'll prohibit the * fault-around logic. */ - if (!pte_none(vmf->pte[count])) + if (!pte_none(ptep_get(&vmf->pte[count]))) goto skip;
count++; diff --git a/mm/ksm.c b/mm/ksm.c index dba6a2eb1a3c..da8416e2debe 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -455,7 +455,7 @@ static int break_ksm_pmd_entry(pmd_t *pmd, unsigned long addr, unsigned long nex page = pfn_swap_entry_to_page(entry); } /* return 1 if the page is an normal ksm page or KSM-placed zero page */ - ret = (page && PageKsm(page)) || is_ksm_zero_pte(*pte); + ret = (page && PageKsm(page)) || is_ksm_zero_pte(ptent); pte_unmap_unlock(pte, ptl); return ret; } diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index 32fa1a22c85a..f9bcf2a4f169 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -313,7 +313,7 @@ static int mfill_atomic_pte_poison(pmd_t *dst_pmd,
ret = -EEXIST; /* Refuse to overwrite any PTE, even a PTE marker (e.g. UFFD WP). */ - if (!pte_none(*dst_pte)) + if (!pte_none(ptep_get(dst_pte))) goto out_unlock;
set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte);