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mm, gup: add missing refcount overflow checks on s390
The mainline commit8fde12ca79
("mm: prevent get_user_pages() from overflowing page refcount") was backported to 4.14.y stable as commit04198de247
. The backport however missed that in 4.14, there are several arch-specific gup.c versions with fast gup implementations, so these do not prevent refcount overflow. This stable-only commit fixes the s390 version, and is based on the backport in SUSE SLES/openSUSE 4.12-based kernels. The remaining architectures with own gup.c are sparc, mips, sh. It's unlikely the known overflow scenario based on FUSE, which needs 140GB of RAM, is a problem for those architectures, and I don't feel confident enough to patch them. Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Sasha Levin <sashal@kernel.org>
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parent
ef04ffdd59
commit
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1 changed files with 6 additions and 3 deletions
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@ -39,7 +39,8 @@ static inline int gup_pte_range(pmd_t *pmdp, pmd_t pmd, unsigned long addr,
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VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
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page = pte_page(pte);
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head = compound_head(page);
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if (!page_cache_get_speculative(head))
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if (unlikely(WARN_ON_ONCE(page_ref_count(head) < 0)
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|| !page_cache_get_speculative(head)))
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return 0;
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if (unlikely(pte_val(pte) != pte_val(*ptep))) {
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put_page(head);
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@ -77,7 +78,8 @@ static inline int gup_huge_pmd(pmd_t *pmdp, pmd_t pmd, unsigned long addr,
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refs++;
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} while (addr += PAGE_SIZE, addr != end);
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if (!page_cache_add_speculative(head, refs)) {
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if (unlikely(WARN_ON_ONCE(page_ref_count(head) < 0)
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|| !page_cache_add_speculative(head, refs))) {
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*nr -= refs;
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return 0;
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}
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@ -151,7 +153,8 @@ static int gup_huge_pud(pud_t *pudp, pud_t pud, unsigned long addr,
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refs++;
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} while (addr += PAGE_SIZE, addr != end);
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if (!page_cache_add_speculative(head, refs)) {
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if (unlikely(WARN_ON_ONCE(page_ref_count(head) < 0)
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|| !page_cache_add_speculative(head, refs))) {
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*nr -= refs;
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return 0;
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}
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