From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5FC287C0BD; Wed, 21 Feb 2024 13:52:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708523523; cv=none; b=K4g9ZdgXpN1wAjRnqF29awf116eNe3pF/VMZLAkQ+prrd3tS38a6ajAZfd0AV8oO3qXs1md6GC6NeK+zulzeIM5NvinFe0O07XLBZextkZqfbs1CMMyoLvJHwmzjAgOr0u+i/gO8/ijEPTcmDhurx6lf6sUnRHhYVYAp9twUkps= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708523523; c=relaxed/simple; bh=XHckwHWCRWPt8MIs7xwnueDYIu/qSXXTDMw5jdirTNg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=dYE1MMYOSOqAzDrXypAtTfVonbUnW2uv9wadwAZjIKJGKwdNxGrb/j2BI/8MZq+KMFwtMyWrxTIF1mjq5dmieCIJ2bY5sTzxuKWbJWw62eleLAHtgtYP2wX3mneyOEiKv3gq88AItm8sL9cbNHi6MRuQrzkb35zPNlNcuCwF7Wc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Oz21U6I7; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="Oz21U6I7" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1553BC433C7; Wed, 21 Feb 2024 13:52:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1708523522; bh=XHckwHWCRWPt8MIs7xwnueDYIu/qSXXTDMw5jdirTNg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Oz21U6I7scBFC2rD0v8WKnVRbKcqHpMPGVFgx6q5KajBCFu547lk0tX5ckxu/tncY edSXchOnkzhsgGOxSi8FPG2ylRj9Dn8ua5jnkhbN0EuCPaUCxNipZPw/MlBMXA7DJm oJ9PBWf2mnApC3YcL63KCv0ZuS6PZOqJmqE0lgMw= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Ryusuke Konishi , syzbot+5c04210f7c7f897c1e7f@syzkaller.appspotmail.com, Andrew Morton Subject: [PATCH 5.15 462/476] nilfs2: fix potential bug in end_buffer_async_write Date: Wed, 21 Feb 2024 14:08:33 +0100 Message-ID: <20240221130025.126829028@linuxfoundation.org> X-Mailer: git-send-email 2.43.2 In-Reply-To: <20240221130007.738356493@linuxfoundation.org> References: <20240221130007.738356493@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ryusuke Konishi commit 5bc09b397cbf1221f8a8aacb1152650c9195b02b upstream. According to a syzbot report, end_buffer_async_write(), which handles the completion of block device writes, may detect abnormal condition of the buffer async_write flag and cause a BUG_ON failure when using nilfs2. Nilfs2 itself does not use end_buffer_async_write(). But, the async_write flag is now used as a marker by commit 7f42ec394156 ("nilfs2: fix issue with race condition of competition between segments for dirty blocks") as a means of resolving double list insertion of dirty blocks in nilfs_lookup_dirty_data_buffers() and nilfs_lookup_node_buffers() and the resulting crash. This modification is safe as long as it is used for file data and b-tree node blocks where the page caches are independent. However, it was irrelevant and redundant to also introduce async_write for segment summary and super root blocks that share buffers with the backing device. This led to the possibility that the BUG_ON check in end_buffer_async_write would fail as described above, if independent writebacks of the backing device occurred in parallel. The use of async_write for segment summary buffers has already been removed in a previous change. Fix this issue by removing the manipulation of the async_write flag for the remaining super root block buffer. Link: https://lkml.kernel.org/r/20240203161645.4992-1-konishi.ryusuke@gmail.com Fixes: 7f42ec394156 ("nilfs2: fix issue with race condition of competition between segments for dirty blocks") Signed-off-by: Ryusuke Konishi Reported-by: syzbot+5c04210f7c7f897c1e7f@syzkaller.appspotmail.com Closes: https://lkml.kernel.org/r/00000000000019a97c05fd42f8c8@google.com Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- fs/nilfs2/segment.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) --- a/fs/nilfs2/segment.c +++ b/fs/nilfs2/segment.c @@ -1702,7 +1702,6 @@ static void nilfs_segctor_prepare_write( list_for_each_entry(bh, &segbuf->sb_payload_buffers, b_assoc_buffers) { - set_buffer_async_write(bh); if (bh == segbuf->sb_super_root) { if (bh->b_page != bd_page) { lock_page(bd_page); @@ -1713,6 +1712,7 @@ static void nilfs_segctor_prepare_write( } break; } + set_buffer_async_write(bh); if (bh->b_page != fs_page) { nilfs_begin_page_io(fs_page); fs_page = bh->b_page; @@ -1798,7 +1798,6 @@ static void nilfs_abort_logs(struct list list_for_each_entry(bh, &segbuf->sb_payload_buffers, b_assoc_buffers) { - clear_buffer_async_write(bh); if (bh == segbuf->sb_super_root) { clear_buffer_uptodate(bh); if (bh->b_page != bd_page) { @@ -1807,6 +1806,7 @@ static void nilfs_abort_logs(struct list } break; } + clear_buffer_async_write(bh); if (bh->b_page != fs_page) { nilfs_end_page_io(fs_page, err); fs_page = bh->b_page; @@ -1894,8 +1894,9 @@ static void nilfs_segctor_complete_write BIT(BH_Delay) | BIT(BH_NILFS_Volatile) | BIT(BH_NILFS_Redirected)); - set_mask_bits(&bh->b_state, clear_bits, set_bits); if (bh == segbuf->sb_super_root) { + set_buffer_uptodate(bh); + clear_buffer_dirty(bh); if (bh->b_page != bd_page) { end_page_writeback(bd_page); bd_page = bh->b_page; @@ -1903,6 +1904,7 @@ static void nilfs_segctor_complete_write update_sr = true; break; } + set_mask_bits(&bh->b_state, clear_bits, set_bits); if (bh->b_page != fs_page) { nilfs_end_page_io(fs_page, 0); fs_page = bh->b_page;