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[203.221.156.192]) by smtp.gmail.com with ESMTPSA id 68sm19272293pfg.90.2021.01.25.20.45.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 25 Jan 2021 20:45:33 -0800 (PST) From: Nicholas Piggin To: linux-mm@kvack.org, Andrew Morton Cc: Nicholas Piggin , linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, Jonathan Cameron , Christoph Hellwig , Christophe Leroy , Rick Edgecombe , Ding Tianhong , Christoph Hellwig Subject: [PATCH v11 02/13] mm: apply_to_pte_range warn and fail if a large pte is encountered Date: Tue, 26 Jan 2021 14:44:59 +1000 Message-Id: <20210126044510.2491820-3-npiggin@gmail.com> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20210126044510.2491820-1-npiggin@gmail.com> References: <20210126044510.2491820-1-npiggin@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org apply_to_pte_range might mistake a large pte for bad, or treat it as a page table, resulting in a crash or corruption. Add a test to warn and return error if large entries are found. Reviewed-by: Christoph Hellwig Signed-off-by: Nicholas Piggin --- mm/memory.c | 66 +++++++++++++++++++++++++++++++++++++++-------------- 1 file changed, 49 insertions(+), 17 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index feff48e1465a..672e39a72788 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2440,13 +2440,21 @@ static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud, } do { next = pmd_addr_end(addr, end); - if (create || !pmd_none_or_clear_bad(pmd)) { - err = apply_to_pte_range(mm, pmd, addr, next, fn, data, - create, mask); - if (err) - break; + if (pmd_none(*pmd) && !create) + continue; + if (WARN_ON_ONCE(pmd_leaf(*pmd))) + return -EINVAL; + if (!pmd_none(*pmd) && WARN_ON_ONCE(pmd_bad(*pmd))) { + if (!create) + continue; + pmd_clear_bad(pmd); } + err = apply_to_pte_range(mm, pmd, addr, next, + fn, data, create, mask); + if (err) + break; } while (pmd++, addr = next, addr != end); + return err; } @@ -2468,13 +2476,21 @@ static int apply_to_pud_range(struct mm_struct *mm, p4d_t *p4d, } do { next = pud_addr_end(addr, end); - if (create || !pud_none_or_clear_bad(pud)) { - err = apply_to_pmd_range(mm, pud, addr, next, fn, data, - create, mask); - if (err) - break; + if (pud_none(*pud) && !create) + continue; + if (WARN_ON_ONCE(pud_leaf(*pud))) + return -EINVAL; + if (!pud_none(*pud) && WARN_ON_ONCE(pud_bad(*pud))) { + if (!create) + continue; + pud_clear_bad(pud); } + err = apply_to_pmd_range(mm, pud, addr, next, + fn, data, create, mask); + if (err) + break; } while (pud++, addr = next, addr != end); + return err; } @@ -2496,13 +2512,21 @@ static int apply_to_p4d_range(struct mm_struct *mm, pgd_t *pgd, } do { next = p4d_addr_end(addr, end); - if (create || !p4d_none_or_clear_bad(p4d)) { - err = apply_to_pud_range(mm, p4d, addr, next, fn, data, - create, mask); - if (err) - break; + if (p4d_none(*p4d) && !create) + continue; + if (WARN_ON_ONCE(p4d_leaf(*p4d))) + return -EINVAL; + if (!p4d_none(*p4d) && WARN_ON_ONCE(p4d_bad(*p4d))) { + if (!create) + continue; + p4d_clear_bad(p4d); } + err = apply_to_pud_range(mm, p4d, addr, next, + fn, data, create, mask); + if (err) + break; } while (p4d++, addr = next, addr != end); + return err; } @@ -2522,9 +2546,17 @@ static int __apply_to_page_range(struct mm_struct *mm, unsigned long addr, pgd = pgd_offset(mm, addr); do { next = pgd_addr_end(addr, end); - if (!create && pgd_none_or_clear_bad(pgd)) + if (pgd_none(*pgd) && !create) continue; - err = apply_to_p4d_range(mm, pgd, addr, next, fn, data, create, &mask); + if (WARN_ON_ONCE(pgd_leaf(*pgd))) + return -EINVAL; + if (!pgd_none(*pgd) && WARN_ON_ONCE(pgd_bad(*pgd))) { + if (!create) + continue; + pgd_clear_bad(pgd); + } + err = apply_to_p4d_range(mm, pgd, addr, next, + fn, data, create, &mask); if (err) break; } while (pgd++, addr = next, addr != end); -- 2.23.0