Commit 93908500 authored Feb 12, 2021 by Linus Torvalds

Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

Pull arm64 fix from Catalin Marinas:
 "Fix PTRACE_PEEKMTETAGS access to an mmapped region before the first
  write"

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64: mte: Allow PTRACE_PEEKMTETAGS access to the zero page

parents dcc0b490 68d54cee

arch/arm64/kernel/cpufeature.c

+1 −5

Original line number	Diff line number	Diff line
		@@ -1701,16 +1701,12 @@ static void bti_enable(const struct arm64_cpu_capabilities *__unused)
		#ifdef CONFIG_ARM64_MTE
		static void cpu_enable_mte(struct arm64_cpu_capabilities const *cap)
		{
		static bool cleared_zero_page = false;

		/*
		* Clear the tags in the zero page. This needs to be done via the
		* linear map which has the Tagged attribute.
		*/
		if (!cleared_zero_page) {
		cleared_zero_page = true;
		if (!test_and_set_bit(PG_mte_tagged, &ZERO_PAGE(0)->flags))
		mte_clear_page_tags(lm_alias(empty_zero_page));
		}

		kasan_init_hw_tags_cpu();
		}

arch/arm64/kernel/mte.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -329,11 +329,12 @@ static int __access_remote_tags(struct mm_struct *mm, unsigned long addr,
		* would cause the existing tags to be cleared if the page
		* was never mapped with PROT_MTE.
		*/
		if (!test_bit(PG_mte_tagged, &page->flags)) {
		if (!(vma->vm_flags & VM_MTE)) {
		ret = -EOPNOTSUPP;
		put_page(page);
		break;
		}
		WARN_ON_ONCE(!test_bit(PG_mte_tagged, &page->flags));

		/* limit access to the end of the page */
		offset = offset_in_page(addr);