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authorJosh Poimboeuf <jpoimboe@redhat.com>2016-10-25 09:51:14 -0500
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-08-11 09:08:47 -0700
commit12f60018f63b899b89299da435ca2de3bd47f2f2 (patch)
treedf7c3e545434c26d28a2db467512d96777b79fd6 /mm
parentbbccdb1e442be9b705564479d8b0c55b9b202dad (diff)
downloadlinux-linaro-stable-12f60018f63b899b89299da435ca2de3bd47f2f2.tar.gz
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 <torvalds@linux-foundation.org> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/6836ff90c45b71d38e5d4405aec56fa9e5d1d4b2.1477405374.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Kees Cook <keescook@google.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/page_alloc.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index bd17a6bdf131..8b80115e4e9e 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5847,8 +5847,8 @@ 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;
}