From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: + mm-kmemleak-annotate-various-data-races-obj-ptr.patch added to -mm tree Date: Thu, 13 Feb 2020 19:06:46 -0800 Message-ID: <20200214030646.yglVwNFVo%akpm@linux-foundation.org> References: <20200203173311.6269a8be06a05e5a4aa08a93@linux-foundation.org> Reply-To: linux-kernel@vger.kernel.org Return-path: Received: from mail.kernel.org ([198.145.29.99]:39824 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727604AbgBNDGr (ORCPT ); Thu, 13 Feb 2020 22:06:47 -0500 In-Reply-To: <20200203173311.6269a8be06a05e5a4aa08a93@linux-foundation.org> Sender: mm-commits-owner@vger.kernel.org List-Id: mm-commits@vger.kernel.org To: cai@lca.pw, catalin.marinas@arm.com, elver@google.com, mm-commits@vger.kernel.org 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 Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Qian Cai 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@lca.pw Signed-off-by: Qian Cai Acked-by: Catalin Marinas Cc: Marco Elver Signed-off-by: Andrew Morton --- 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@lca.pw 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