From e6c7308ec57d6ee9936cd021873ff7b5d4e7be5b Mon Sep 17 00:00:00 2001 From: Josh Poimboeuf Date: Tue, 25 Oct 2016 09:51:14 -0500 Subject: mm/page_alloc: Remove kernel address exposure in free_reserved_area() commit adb1fe9ae2ee6ef6bc10f3d5a588020e7664dfa7 upstream. Linus suggested we try to remove some of the low-hanging fruit related to kernel address exposure in dmesg. The only leaks I see on my local system are: Freeing SMP alternatives memory: 32K (ffffffff9e309000 - ffffffff9e311000) Freeing initrd memory: 10588K (ffffa0b736b42000 - ffffa0b737599000) Freeing unused kernel memory: 3592K (ffffffff9df87000 - ffffffff9e309000) Freeing unused kernel memory: 1352K (ffffa0b7288ae000 - ffffa0b728a00000) Freeing unused kernel memory: 632K (ffffa0b728d62000 - ffffa0b728e00000) Linus says: "I suspect we should just remove [the addresses in the 'Freeing' messages]. I'm sure they are useful in theory, but I suspect they were more useful back when the whole "free init memory" was originally done. These days, if we have a use-after-free, I suspect the init-mem situation is the easiest situation by far. Compared to all the dynamic allocations which are much more likely to show it anyway. So having debug output for that case is likely not all that productive." With this patch the freeing messages now look like this: Freeing SMP alternatives memory: 32K Freeing initrd memory: 10588K Freeing unused kernel memory: 3592K Freeing unused kernel memory: 1352K Freeing unused kernel memory: 632K Suggested-by: Linus Torvalds Signed-off-by: Josh Poimboeuf Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/6836ff90c45b71d38e5d4405aec56fa9e5d1d4b2.1477405374.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar Cc: Kees Cook Signed-off-by: Greg Kroah-Hartman --- mm/page_alloc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'mm') diff --git a/mm/page_alloc.c b/mm/page_alloc.c index ded3507dc793..bad1467e9f8c 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -5467,8 +5467,8 @@ unsigned long free_reserved_area(void *start, void *end, int poison, char *s) } if (pages && s) - pr_info("Freeing %s memory: %ldK (%p - %p)\n", - s, pages << (PAGE_SHIFT - 10), start, end); + pr_info("Freeing %s memory: %ldK\n", + s, pages << (PAGE_SHIFT - 10)); return pages; } -- cgit v1.2.3