From: Qian Cai <cai@lca.pw>
To: akpm@linux-foundation.org
Cc: elver@google.com, catalin.marinas@arm.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, Qian Cai <cai@lca.pw>
Subject: [PATCH -next] mm/kmemleak: annotate a data race in checksum
Date: Tue, 17 Mar 2020 09:21:57 -0400 [thread overview]
Message-ID: <20200317132157.1272-1-cai@lca.pw> (raw)
Even if KCSAN is disabled for kmemleak, update_checksum() could still
call crc32() (which is outside of kmemleak.c) to dereference
object->pointer. Thus, the value of object->pointer could be accessed
concurrently as noticed by KCSAN,
BUG: KCSAN: data-race in crc32_le_base / do_raw_spin_lock
write to 0xffffb0ea683a7d50 of 4 bytes by task 23575 on cpu 12:
do_raw_spin_lock+0x114/0x200
debug_spin_lock_after at kernel/locking/spinlock_debug.c:91
(inlined by) do_raw_spin_lock at kernel/locking/spinlock_debug.c:115
_raw_spin_lock+0x40/0x50
__handle_mm_fault+0xa9e/0xd00
handle_mm_fault+0xfc/0x2f0
do_page_fault+0x263/0x6f9
page_fault+0x34/0x40
read to 0xffffb0ea683a7d50 of 4 bytes by task 839 on cpu 60:
crc32_le_base+0x67/0x350
crc32_le_base+0x67/0x350:
crc32_body at lib/crc32.c:106
(inlined by) crc32_le_generic at lib/crc32.c:179
(inlined by) crc32_le at lib/crc32.c:197
kmemleak_scan+0x528/0xd90
update_checksum at mm/kmemleak.c:1172
(inlined by) kmemleak_scan at mm/kmemleak.c:1497
kmemleak_scan_thread+0xcc/0xfa
kthread+0x1e0/0x200
ret_from_fork+0x27/0x50
If a shattered value was returned due to a data race, it will be
corrected in the next scan. Thus, annotate it as an intentional data
race using the data_race() macro.
Signed-off-by: Qian Cai <cai@lca.pw>
---
mm/kmemleak.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index e362dc3d2028..d3327756c3a4 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -1169,7 +1169,12 @@ static bool update_checksum(struct kmemleak_object *object)
u32 old_csum = object->checksum;
kasan_disable_current();
- object->checksum = crc32(0, (void *)object->pointer, object->size);
+ /*
+ * crc32() will dereference object->pointer. If an unstable value was
+ * returned due to a data race, it will be corrected in the next scan.
+ */
+ object->checksum = data_race(crc32(0, (void *)object->pointer,
+ object->size));
kasan_enable_current();
return object->checksum != old_csum;
--
2.21.0 (Apple Git-122.2)
next reply other threads:[~2020-03-17 13:22 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-17 13:21 Qian Cai [this message]
2020-03-17 13:31 ` [PATCH -next] mm/kmemleak: annotate a data race in checksum Marco Elver
2020-03-17 13:42 ` Qian Cai
-- strict thread matches above, loose matches on Subject: below --
2020-02-11 16:24 Qian Cai
2020-02-11 16:51 ` Catalin Marinas
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200317132157.1272-1-cai@lca.pw \
--to=cai@lca.pw \
--cc=akpm@linux-foundation.org \
--cc=catalin.marinas@arm.com \
--cc=elver@google.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).