Commit 0c95cba4 authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Linus Torvalds
Browse files

mm: apply_to_pte_range warn and fail if a large pte is encountered 

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.

Link: https://lkml.kernel.org/r/20210317062402.533919-4-npiggin@gmail.com


Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
Reviewed-by: default avatarMiaohe Lin <linmiaohe@huawei.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Ding Tianhong <dingtianhong@huawei.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent c0eb315a

mm/memory.c

+49 −17
Original line number Diff line number Diff line
@@ -2457,13 +2457,21 @@ 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 (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;

}
@@ -2485,13 +2493,21 @@ 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 (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;

}
@@ -2513,13 +2529,21 @@ 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 (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;

}
@@ -2539,9 +2563,17 @@ 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);