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Commit 22eccdd7 authored by Dan Carpenter's avatar Dan Carpenter Committed by Linus Torvalds
Browse files

ksm: check for ERR_PTR from follow_page() 



The follow_page() function can potentially return -EFAULT so I added
checks for this.

Also I silenced an uninitialized variable warning on my version of gcc
(version 4.3.2).

Signed-off-by: default avatarDan Carpenter <error27@gmail.com>
Acked-by: default avatarRik van Riel <riel@redhat.com>
Acked-by: default avatarIzik Eidus <ieidus@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 453dc659

mm/ksm.c

+6 −6
Original line number Diff line number Diff line
@@ -365,7 +365,7 @@ static int break_ksm(struct vm_area_struct *vma, unsigned long addr) 
	do {

		cond_resched();

		page = follow_page(vma, addr, FOLL_GET);

		if (!page)

		if (IS_ERR_OR_NULL(page))

			break;

		if (PageKsm(page))

			ret = handle_mm_fault(vma->vm_mm, vma, addr,
@@ -447,7 +447,7 @@ static struct page *get_mergeable_page(struct rmap_item *rmap_item) 
		goto out;



	page = follow_page(vma, addr, FOLL_GET);

	if (!page)

	if (IS_ERR_OR_NULL(page))

		goto out;

	if (PageAnon(page)) {

		flush_anon_page(vma, page, addr);
@@ -1086,7 +1086,7 @@ struct rmap_item *unstable_tree_search_insert(struct rmap_item *rmap_item, 
		cond_resched();

		tree_rmap_item = rb_entry(*new, struct rmap_item, node);

		tree_page = get_mergeable_page(tree_rmap_item);

		if (!tree_page)

		if (IS_ERR_OR_NULL(tree_page))

			return NULL;



		/*
@@ -1294,7 +1294,7 @@ static struct rmap_item *scan_get_next_rmap_item(struct page **page) 
			if (ksm_test_exit(mm))

				break;

			*page = follow_page(vma, ksm_scan.address, FOLL_GET);

			if (*page && PageAnon(*page)) {

			if (!IS_ERR_OR_NULL(*page) && PageAnon(*page)) {

				flush_anon_page(vma, *page, ksm_scan.address);

				flush_dcache_page(*page);

				rmap_item = get_next_rmap_item(slot,
@@ -1308,7 +1308,7 @@ static struct rmap_item *scan_get_next_rmap_item(struct page **page) 
				up_read(&mm->mmap_sem);

				return rmap_item;

			}

			if (*page)

			if (!IS_ERR_OR_NULL(*page))

				put_page(*page);

			ksm_scan.address += PAGE_SIZE;

			cond_resched();
@@ -1367,7 +1367,7 @@ static struct rmap_item *scan_get_next_rmap_item(struct page **page) 
static void ksm_do_scan(unsigned int scan_npages)

{

	struct rmap_item *rmap_item;

	struct page *page;

	struct page *uninitialized_var(page);



	while (scan_npages--) {

		cond_resched();