diff options
author | Qian Cai <cai@lca.pw> | 2019-03-06 02:41:24 +0300 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-04-05 23:32:59 +0300 |
commit | a6c56bf63e875458dde73afde909184e34c99080 (patch) | |
tree | abfb0a616b1899f69ff5b135bb40163993177f17 /mm/page_poison.c | |
parent | d609ecd887f8dd8288b9ff58042381a0ce801ec0 (diff) | |
download | linux-a6c56bf63e875458dde73afde909184e34c99080.tar.xz |
page_poison: play nicely with KASAN
[ Upstream commit 4117992df66a26fa33908b4969e04801534baab1 ]
KASAN does not play well with the page poisoning (CONFIG_PAGE_POISONING).
It triggers false positives in the allocation path:
BUG: KASAN: use-after-free in memchr_inv+0x2ea/0x330
Read of size 8 at addr ffff88881f800000 by task swapper/0
CPU: 0 PID: 0 Comm: swapper Not tainted 5.0.0-rc1+ #54
Call Trace:
dump_stack+0xe0/0x19a
print_address_description.cold.2+0x9/0x28b
kasan_report.cold.3+0x7a/0xb5
__asan_report_load8_noabort+0x19/0x20
memchr_inv+0x2ea/0x330
kernel_poison_pages+0x103/0x3d5
get_page_from_freelist+0x15e7/0x4d90
because KASAN has not yet unpoisoned the shadow page for allocation
before it checks memchr_inv() but only found a stale poison pattern.
Also, false positives in free path,
BUG: KASAN: slab-out-of-bounds in kernel_poison_pages+0x29e/0x3d5
Write of size 4096 at addr ffff8888112cc000 by task swapper/0/1
CPU: 5 PID: 1 Comm: swapper/0 Not tainted 5.0.0-rc1+ #55
Call Trace:
dump_stack+0xe0/0x19a
print_address_description.cold.2+0x9/0x28b
kasan_report.cold.3+0x7a/0xb5
check_memory_region+0x22d/0x250
memset+0x28/0x40
kernel_poison_pages+0x29e/0x3d5
__free_pages_ok+0x75f/0x13e0
due to KASAN adds poisoned redzones around slab objects, but the page
poisoning needs to poison the whole page.
Link: http://lkml.kernel.org/r/20190114233405.67843-1-cai@lca.pw
Signed-off-by: Qian Cai <cai@lca.pw>
Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'mm/page_poison.c')
-rw-r--r-- | mm/page_poison.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/mm/page_poison.c b/mm/page_poison.c index aa2b3d34e8ea..6cfa8e7d7213 100644 --- a/mm/page_poison.c +++ b/mm/page_poison.c @@ -6,6 +6,7 @@ #include <linux/page_ext.h> #include <linux/poison.h> #include <linux/ratelimit.h> +#include <linux/kasan.h> static bool want_page_poisoning __read_mostly; @@ -34,7 +35,10 @@ static void poison_page(struct page *page) { void *addr = kmap_atomic(page); + /* KASAN still think the page is in-use, so skip it. */ + kasan_disable_current(); memset(addr, PAGE_POISON, PAGE_SIZE); + kasan_enable_current(); kunmap_atomic(addr); } |