The patch titled
Subject: mm/kmemleak: annotate various data races obj->ptr
has been added to the -mm tree. Its filename is
mm-kmemleak-annotate-various-data-races-obj-ptr.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-kmemleak-annotate-various-data-races-obj-ptr.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-kmemleak-annotate-various-data-races-obj-ptr.patch
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------------------------------------------------------
From: Qian Cai <cai@xxxxxx>
Subject: mm/kmemleak: annotate various data races obj->ptr
The value of object->pointer could be accessed concurrently as noticed
by KCSAN,
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
write to 0xffff939bf07b95b8 of 4 bytes by interrupt on cpu 119:
__free_object+0x884/0xcb0
__free_object at lib/debugobjects.c:359
__debug_check_no_obj_freed+0x19d/0x370
debug_check_no_obj_freed+0x41/0x4b
slab_free_freelist_hook+0xfb/0x1c0
kmem_cache_free+0x10c/0x3a0
free_object_rcu+0x1ca/0x260
rcu_core+0x677/0xcc0
rcu_core_si+0x17/0x20
__do_softirq+0xd9/0x57c
run_ksoftirqd+0x29/0x50
smpboot_thread_fn+0x222/0x3f0
kthread+0x1e0/0x200
ret_from_fork+0x27/0x50
read to 0xffff939bf07b95b8 of 8 bytes by task 838 on cpu 109:
scan_block+0x69/0x190
scan_block at mm/kmemleak.c:1250
kmemleak_scan+0x249/0xd90
scan_large_block at mm/kmemleak.c:1309
(inlined by) kmemleak_scan at mm/kmemleak.c:1434
kmemleak_scan_thread+0xcc/0xfa
kthread+0x1e0/0x200
ret_from_fork+0x27/0x50
crc32() will dereference object->pointer. If a shattered value was
returned due to a data race, it will be corrected in the next scan.
scan_block() will dereference a range of addresses (e.g., percpu sections)
to search for valid pointers. Even if a data race heppens, it will cause
no issue because the code here does not care about the exact value of a
non-pointer. Thus, mark them as intentional data races using the
data_race() macro.
Link: http://lkml.kernel.org/r/1581615390-9720-1-git-send-email-cai@xxxxxx
Signed-off-by: Qian Cai <cai@xxxxxx>
Acked-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Marco Elver <elver@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/kmemleak.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
--- a/mm/kmemleak.c~mm-kmemleak-annotate-various-data-races-obj-ptr
+++ a/mm/kmemleak.c
@@ -1169,7 +1169,12 @@ static bool update_checksum(struct kmeml
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;
@@ -1243,7 +1248,7 @@ static void scan_block(void *_start, voi
break;
kasan_disable_current();
- pointer = *ptr;
+ pointer = data_race(*ptr);
kasan_enable_current();
untagged_ptr = (unsigned long)kasan_reset_tag((void *)pointer);
_
Patches currently in -mm which might be from cai@xxxxxx are
mm-kmemleak-annotate-various-data-races-obj-ptr.patch
mm-kmemleak-annotate-a-data-race-in-checksum.patch
mm-swapfile-fix-and-annotate-various-data-races.patch
mm-page_counter-fix-various-data-races-at-memsw.patch
mm-memcontrol-fix-a-data-race-in-scan-count.patch
mm-list_lru-fix-a-data-race-in-list_lru_count_one.patch
mm-mempool-fix-a-data-race-in-mempool_free.patch
mm-util-annotate-an-data-race-at-vm_committed_as.patch
mm-rmap-annotate-a-data-race-at-tlb_flush_batched.patch
mm-frontswap-mark-various-intentional-data-races.patch
mm-page_io-mark-various-intentional-data-races.patch
mm-swap_state-mark-various-intentional-data-races.patch
