[PATCH] swsusp: prevent possible image corruption on resume (4a3b98a4) · Commits · 戴 / test

The function free_pagedir() used by swsusp for freeing its internal data structures clears the PG_nosave and PG_nosave_free flags for each page being freed. However, during resume PG_nosave_free set means that the page in question is "unsafe" (ie. it will be overwritten in the process of restoring the saved system state from the image), so it should not be used for the image data. Therefore free_pagedir() should not clear PG_nosave_free if it's called during resume (otherwise "unsafe" pages freed by it may be used for storing the image data and the data may get corrupted later on). Signed-off-by:

Rafael J. Wysocki <rjw@sisk.pl> Acked-by:

Pavel Machek <pavel@ucw.cz> Signed-off-by:

Andrew Morton <akpm@osdl.org> Signed-off-by:

Linus Torvalds <torvalds@osdl.org>

kernel/power/snapshot.c

+5 −4

Original line number	Diff line number	Diff line
		@@ -240,13 +240,14 @@ static void copy_data_pages(struct pbe *pblist)
		* free_pagedir - free pages allocated with alloc_pagedir()
		*/

		static void free_pagedir(struct pbe *pblist)
		static void free_pagedir(struct pbe *pblist, int clear_nosave_free)
		{
		struct pbe *pbe;

		while (pblist) {
		pbe = (pblist + PB_PAGE_SKIP)->next;
		ClearPageNosave(virt_to_page(pblist));
		if (clear_nosave_free)
		ClearPageNosaveFree(virt_to_page(pblist));
		free_page((unsigned long)pblist);
		pblist = pbe;
		@@ -389,7 +390,7 @@ struct pbe *alloc_pagedir(unsigned int nr_pages, gfp_t gfp_mask, int safe_needed
		pbe->next = alloc_image_page(gfp_mask, safe_needed);
		}
		if (!pbe) { /* get_zeroed_page() failed */
		free_pagedir(pblist);
		free_pagedir(pblist, 1);
		pblist = NULL;
		} else
		create_pbe_list(pblist, nr_pages);
		@@ -736,7 +737,7 @@ static int create_image(struct snapshot_handle *handle)
		pblist = alloc_pagedir(nr_copy_pages, GFP_ATOMIC, 1);
		if (pblist)
		copy_page_backup_list(pblist, p);
		free_pagedir(p);
		free_pagedir(p, 0);
		if (!pblist)
		error = -ENOMEM;
		}

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