From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 77FFBC31E49 for ; Wed, 19 Jun 2019 06:16:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 47DB420679 for ; Wed, 19 Jun 2019 06:16:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725946AbfFSGQR (ORCPT ); Wed, 19 Jun 2019 02:16:17 -0400 Received: from mx2.suse.de ([195.135.220.15]:52356 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725892AbfFSGQR (ORCPT ); Wed, 19 Jun 2019 02:16:17 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id DF836AE56 for ; Wed, 19 Jun 2019 06:16:13 +0000 (UTC) Subject: Re: [PATCH] btrfs-progs: delayed-ref: Fix memory leak and use-after-free caused by wrong condition to free delayed ref/head. To: Qu Wenruo , linux-btrfs@vger.kernel.org References: <20190613073340.19851-1-wqu@suse.com> From: Nikolay Borisov Openpgp: preference=signencrypt Autocrypt: addr=nborisov@suse.com; prefer-encrypt=mutual; keydata= mQINBFiKBz4BEADNHZmqwhuN6EAzXj9SpPpH/nSSP8YgfwoOqwrP+JR4pIqRK0AWWeWCSwmZ T7g+RbfPFlmQp+EwFWOtABXlKC54zgSf+uulGwx5JAUFVUIRBmnHOYi/lUiE0yhpnb1KCA7f u/W+DkwGerXqhhe9TvQoGwgCKNfzFPZoM+gZrm+kWv03QLUCr210n4cwaCPJ0Nr9Z3c582xc bCUVbsjt7BN0CFa2BByulrx5xD9sDAYIqfLCcZetAqsTRGxM7LD0kh5WlKzOeAXj5r8DOrU2 GdZS33uKZI/kZJZVytSmZpswDsKhnGzRN1BANGP8sC+WD4eRXajOmNh2HL4P+meO1TlM3GLl EQd2shHFY0qjEo7wxKZI1RyZZ5AgJnSmehrPCyuIyVY210CbMaIKHUIsTqRgY5GaNME24w7h TyyVCy2qAM8fLJ4Vw5bycM/u5xfWm7gyTb9V1TkZ3o1MTrEsrcqFiRrBY94Rs0oQkZvunqia c+NprYSaOG1Cta14o94eMH271Kka/reEwSZkC7T+o9hZ4zi2CcLcY0DXj0qdId7vUKSJjEep c++s8ncFekh1MPhkOgNj8pk17OAESanmDwksmzh1j12lgA5lTFPrJeRNu6/isC2zyZhTwMWs k3LkcTa8ZXxh0RfWAqgx/ogKPk4ZxOXQEZetkEyTFghbRH2BIwARAQABtCNOaWtvbGF5IEJv cmlzb3YgPG5ib3Jpc292QHN1c2UuY29tPokCOAQTAQIAIgUCWIo48QIbAwYLCQgHAwIGFQgC CQoLBBYCAwECHgECF4AACgkQcb6CRuU/KFc0eg/9GLD3wTQz9iZHMFbjiqTCitD7B6dTLV1C ddZVlC8Hm/TophPts1bWZORAmYIihHHI1EIF19+bfIr46pvfTu0yFrJDLOADMDH+Ufzsfy2v HSqqWV/nOSWGXzh8bgg/ncLwrIdEwBQBN9SDS6aqsglagvwFD91UCg/TshLlRxD5BOnuzfzI Leyx2c6YmH7Oa1R4MX9Jo79SaKwdHt2yRN3SochVtxCyafDlZsE/efp21pMiaK1HoCOZTBp5 VzrIP85GATh18pN7YR9CuPxxN0V6IzT7IlhS4Jgj0NXh6vi1DlmKspr+FOevu4RVXqqcNTSS E2rycB2v6cttH21UUdu/0FtMBKh+rv8+yD49FxMYnTi1jwVzr208vDdRU2v7Ij/TxYt/v4O8 V+jNRKy5Fevca/1xroQBICXsNoFLr10X5IjmhAhqIH8Atpz/89ItS3+HWuE4BHB6RRLM0gy8 T7rN6ja+KegOGikp/VTwBlszhvfLhyoyjXI44Tf3oLSFM+8+qG3B7MNBHOt60CQlMkq0fGXd mm4xENl/SSeHsiomdveeq7cNGpHi6i6ntZK33XJLwvyf00PD7tip/GUj0Dic/ZUsoPSTF/mG EpuQiUZs8X2xjK/AS/l3wa4Kz2tlcOKSKpIpna7V1+CMNkNzaCOlbv7QwprAerKYywPCoOSC 7P25Ag0EWIoHPgEQAMiUqvRBZNvPvki34O/dcTodvLSyOmK/MMBDrzN8Cnk302XfnGlW/YAQ csMWISKKSpStc6tmD+2Y0z9WjyRqFr3EGfH1RXSv9Z1vmfPzU42jsdZn667UxrRcVQXUgoKg QYx055Q2FdUeaZSaivoIBD9WtJq/66UPXRRr4H/+Y5FaUZx+gWNGmBT6a0S/GQnHb9g3nonD jmDKGw+YO4P6aEMxyy3k9PstaoiyBXnzQASzdOi39BgWQuZfIQjN0aW+Dm8kOAfT5i/yk59h VV6v3NLHBjHVw9kHli3jwvsizIX9X2W8tb1SefaVxqvqO1132AO8V9CbE1DcVT8fzICvGi42 FoV/k0QOGwq+LmLf0t04Q0csEl+h69ZcqeBSQcIMm/Ir+NorfCr6HjrB6lW7giBkQl6hhomn l1mtDP6MTdbyYzEiBFcwQD4terc7S/8ELRRybWQHQp7sxQM/Lnuhs77MgY/e6c5AVWnMKd/z MKm4ru7A8+8gdHeydrRQSWDaVbfy3Hup0Ia76J9FaolnjB8YLUOJPdhI2vbvNCQ2ipxw3Y3c KhVIpGYqwdvFIiz0Fej7wnJICIrpJs/+XLQHyqcmERn3s/iWwBpeogrx2Lf8AGezqnv9woq7 OSoWlwXDJiUdaqPEB/HmGfqoRRN20jx+OOvuaBMPAPb+aKJyle8zABEBAAGJAh8EGAECAAkF AliKBz4CGwwACgkQcb6CRuU/KFdacg/+M3V3Ti9JYZEiIyVhqs+yHb6NMI1R0kkAmzsGQ1jU zSQUz9AVMR6T7v2fIETTT/f5Oout0+Hi9cY8uLpk8CWno9V9eR/B7Ifs2pAA8lh2nW43FFwp IDiSuDbH6oTLmiGCB206IvSuaQCp1fed8U6yuqGFcnf0ZpJm/sILG2ECdFK9RYnMIaeqlNQm iZicBY2lmlYFBEaMXHoy+K7nbOuizPWdUKoKHq+tmZ3iA+qL5s6Qlm4trH28/fPpFuOmgP8P K+7LpYLNSl1oQUr+WlqilPAuLcCo5Vdl7M7VFLMq4xxY/dY99aZx0ZJQYFx0w/6UkbDdFLzN upT7NIN68lZRucImffiWyN7CjH23X3Tni8bS9ubo7OON68NbPz1YIaYaHmnVQCjDyDXkQoKC R82Vf9mf5slj0Vlpf+/Wpsv/TH8X32ajva37oEQTkWNMsDxyw3aPSps6MaMafcN7k60y2Wk/ TCiLsRHFfMHFY6/lq/c0ZdOsGjgpIK0G0z6et9YU6MaPuKwNY4kBdjPNBwHreucrQVUdqRRm RcxmGC6ohvpqVGfhT48ZPZKZEWM+tZky0mO7bhZYxMXyVjBn4EoNTsXy1et9Y1dU3HVJ8fod 5UqrNrzIQFbdeM0/JqSLrtlTcXKJ7cYFa9ZM2AP7UIN9n1UWxq+OPY9YMOewVfYtL8M= Message-ID: <927951dd-7416-56e7-854c-e56f0e90fdf1@suse.com> Date: Wed, 19 Jun 2019 09:16:13 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <20190613073340.19851-1-wqu@suse.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On 13.06.19 г. 10:33 ч., Qu Wenruo wrote: > [BUG] > When btrfs-progs is compiled with D=asan, it can't pass even the very > basic fsck tests due to btrfs-image has memory leak: > === START TEST /home/adam/btrfs/btrfs-progs/tests//fsck-tests/001-bad-file-extent-bytenr > restoring image default_case.img > > ================================================================= > ==7790==ERROR: LeakSanitizer: detected memory leaks > > Direct leak of 104 byte(s) in 1 object(s) allocated from: > #0 0x7f1d3b738389 in __interceptor_malloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cc:86 > #1 0x560ca6b7f4ff in btrfs_add_delayed_tree_ref /home/adam/btrfs/btrfs-progs/delayed-ref.c:569 > #2 0x560ca6af2d0b in btrfs_free_extent /home/adam/btrfs/btrfs-progs/extent-tree.c:2155 > #3 0x560ca6ac16ca in __btrfs_cow_block /home/adam/btrfs/btrfs-progs/ctree.c:319 > #4 0x560ca6ac1d8c in btrfs_cow_block /home/adam/btrfs/btrfs-progs/ctree.c:383 > #5 0x560ca6ac6c8e in btrfs_search_slot /home/adam/btrfs/btrfs-progs/ctree.c:1153 > #6 0x560ca6ab7e83 in fixup_device_size image/main.c:2113 > #7 0x560ca6ab9279 in fixup_chunks_and_devices image/main.c:2333 > #8 0x560ca6ab9ada in restore_metadump image/main.c:2455 > #9 0x560ca6abaeba in main image/main.c:2723 > #10 0x7f1d3b148ce2 in __libc_start_main (/usr/lib/libc.so.6+0x23ce2) > > ... tons of similar leakage for delayed_tree_ref ... > > Direct leak of 96 byte(s) in 1 object(s) allocated from: > #0 0x7f1d3b738389 in __interceptor_malloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cc:86 > #1 0x560ca6b7f5fb in btrfs_add_delayed_tree_ref /home/adam/btrfs/btrfs-progs/delayed-ref.c:583 > #2 0x560ca6af5679 in alloc_tree_block /home/adam/btrfs/btrfs-progs/extent-tree.c:2503 > #3 0x560ca6af57ac in btrfs_alloc_free_block /home/adam/btrfs/btrfs-progs/extent-tree.c:2524 > #4 0x560ca6ac115b in __btrfs_cow_block /home/adam/btrfs/btrfs-progs/ctree.c:290 > #5 0x560ca6ac1d8c in btrfs_cow_block /home/adam/btrfs/btrfs-progs/ctree.c:383 > #6 0x560ca6b7bb15 in commit_tree_roots /home/adam/btrfs/btrfs-progs/transaction.c:98 > #7 0x560ca6b7c525 in btrfs_commit_transaction /home/adam/btrfs/btrfs-progs/transaction.c:192 > #8 0x560ca6ab92be in fixup_chunks_and_devices image/main.c:2337 > #9 0x560ca6ab9ada in restore_metadump image/main.c:2455 > #10 0x560ca6abaeba in main image/main.c:2723 > #11 0x7f1d3b148ce2 in __libc_start_main (/usr/lib/libc.so.6+0x23ce2) > > ... tons of similar leakage for delayed_ref_head ... > > SUMMARY: AddressSanitizer: 1600 byte(s) leaked in 16 allocation(s). > failed to restore image ./default_case.img > > [CAUSE] > Commit c6039704c580 ("btrfs-progs: Add delayed refs infrastructure") > introduces delayed ref infrastructure for free space tree, however the > refcount_dec_and_test() from kernel code is wrongly backported. > > refcount_dec_and_test() will return true if the refcount reaches 0. > So kernel code will free the allocated space as expected: > if (refcount_dec_and_test(&ref->refs)) { > kmem_cache_free(); > } > > However btrfs-progs backport is using the opposite condition: > if (--ref->refs) { > kfree(); > } > > This will not free the memory for the last user, but for refs >= 2. > Causing both use-after-free and memory leak for any offline write > operation. > > [FIX] > Fix the (--ref->refs) condition to (--ref->refs == 0) to fix the > backport error. > > Fixes: c6039704c580 ("btrfs-progs: Add delayed refs infrastructure") > Signed-off-by: Qu Wenruo Reviewed-by: Nikolay Borisov > --- > delayed-ref.h | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/delayed-ref.h b/delayed-ref.h > index efc855eff621..2ccfd27c2b95 100644 > --- a/delayed-ref.h > +++ b/delayed-ref.h > @@ -161,7 +161,7 @@ btrfs_free_delayed_extent_op(struct btrfs_delayed_extent_op *op) > static inline void btrfs_put_delayed_ref(struct btrfs_delayed_ref_node *ref) > { > WARN_ON(ref->refs == 0); > - if (--ref->refs) { > + if (--ref->refs == 0) { > WARN_ON(ref->in_tree); > switch (ref->type) { > case BTRFS_TREE_BLOCK_REF_KEY: > @@ -180,7 +180,7 @@ static inline void btrfs_put_delayed_ref(struct btrfs_delayed_ref_node *ref) > > static inline void btrfs_put_delayed_ref_head(struct btrfs_delayed_ref_head *head) > { > - if (--head->refs) > + if (--head->refs == 0) > kfree(head); > } > >