From patchwork Mon May 1 18:26:58 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Darrick J. Wong" X-Patchwork-Id: 13227873 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B4AC8C77B73 for ; Mon, 1 May 2023 18:27:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229688AbjEAS1C (ORCPT ); Mon, 1 May 2023 14:27:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50962 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229653AbjEAS1B (ORCPT ); Mon, 1 May 2023 14:27:01 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 47E16DF for ; Mon, 1 May 2023 11:27:00 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id D943061E84 for ; Mon, 1 May 2023 18:26:59 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 40604C433D2; Mon, 1 May 2023 18:26:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1682965619; bh=B/KXX9/QYgTj0QZ0Ow25WYl4nwu5/N83I2/JU3lhTDc=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=L6PrFr05S0+wjMGu6DNmB+X42BebdL0TQV4wYZSdWbVywLo1OTNyn2aldLAeE6Nra 3VvqdG0a/1SCk/KIOsiUH01CuUsE13WOHS5qrGucLFNawIy2rcpU0KcvA7EWqLflJo mkDof9vRbukHzahLlGTWZwsZE3QXJ/cNAhS9zltGDfHIj75HmAt2InE2GESC7Wy6iw Khh2Yw5UF06xYTcfRcWESTCzY98xAb9714GcBPXQVFxQ8wssT+v9xmROeC+0iK6orL HjF2ir2zc/5Of0Ox7J0p5D5Ie7UmKizvrvsYIqsT9v6FcQhWOSP3t3HMj6iC48CG9n XzB0VSJ5R/xVg== Subject: [PATCH 1/4] xfs: don't unconditionally null args->pag in xfs_bmap_btalloc_at_eof From: "Darrick J. Wong" To: david@fromorbit.com, djwong@kernel.org Cc: Dave Chinner , linux-xfs@vger.kernel.org Date: Mon, 01 May 2023 11:26:58 -0700 Message-ID: <168296561879.290030.9885864692870487053.stgit@frogsfrogsfrogs> In-Reply-To: <168296561299.290030.5324305660599413777.stgit@frogsfrogsfrogs> References: <168296561299.290030.5324305660599413777.stgit@frogsfrogsfrogs> User-Agent: StGit/0.19 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org From: Darrick J. Wong xfs/170 on a filesystem with su=128k,sw=4 produces this splat: BUG: kernel NULL pointer dereference, address: 0000000000000010 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page PGD 0 P4D 0 Oops: 0002 [#1] PREEMPT SMP CPU: 1 PID: 4022907 Comm: dd Tainted: G W 6.3.0-xfsx #2 6ebeeffbe9577d32 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20171121_152543-x86-ol7-bu RIP: 0010:xfs_perag_rele+0x10/0x70 [xfs] RSP: 0018:ffffc90001e43858 EFLAGS: 00010217 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000100 RDX: ffffffffa054e717 RSI: 0000000000000005 RDI: 0000000000000000 RBP: ffff888194eea000 R08: 0000000000000000 R09: 0000000000000037 R10: ffff888100ac1cb0 R11: 0000000000000018 R12: 0000000000000000 R13: ffffc90001e43a38 R14: ffff888194eea000 R15: ffff888194eea000 FS: 00007f93d1a0e740(0000) GS:ffff88843fc80000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000010 CR3: 000000018a34f000 CR4: 00000000003506e0 Call Trace: xfs_bmap_btalloc+0x1a7/0x5d0 [xfs f85291d6841cbb3dc740083f1f331c0327394518] xfs_bmapi_allocate+0xee/0x470 [xfs f85291d6841cbb3dc740083f1f331c0327394518] xfs_bmapi_write+0x539/0x9e0 [xfs f85291d6841cbb3dc740083f1f331c0327394518] xfs_iomap_write_direct+0x1bb/0x2b0 [xfs f85291d6841cbb3dc740083f1f331c0327394518] xfs_direct_write_iomap_begin+0x51c/0x710 [xfs f85291d6841cbb3dc740083f1f331c0327394518] iomap_iter+0x132/0x2f0 __iomap_dio_rw+0x2f8/0x840 iomap_dio_rw+0xe/0x30 xfs_file_dio_write_aligned+0xad/0x180 [xfs f85291d6841cbb3dc740083f1f331c0327394518] xfs_file_write_iter+0xfb/0x190 [xfs f85291d6841cbb3dc740083f1f331c0327394518] vfs_write+0x2eb/0x410 ksys_write+0x65/0xe0 do_syscall_64+0x2b/0x80 This crash occurs under the "out_low_space" label. We grabbed a perag reference, passed it via args->pag into xfs_bmap_btalloc_at_eof, and afterwards args->pag is NULL. Fix the second function not to clobber args->pag if the caller had passed one in. Fixes: 85843327094f ("xfs: factor xfs_bmap_btalloc()") Signed-off-by: Darrick J. Wong Reviewed-by: Dave Chinner --- fs/xfs/libxfs/xfs_bmap.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c index b512de0540d5..cd8870a16fd1 100644 --- a/fs/xfs/libxfs/xfs_bmap.c +++ b/fs/xfs/libxfs/xfs_bmap.c @@ -3494,8 +3494,10 @@ xfs_bmap_btalloc_at_eof( if (!caller_pag) args->pag = xfs_perag_get(mp, XFS_FSB_TO_AGNO(mp, ap->blkno)); error = xfs_alloc_vextent_exact_bno(args, ap->blkno); - if (!caller_pag) + if (!caller_pag) { xfs_perag_put(args->pag); + args->pag = NULL; + } if (error) return error; @@ -3505,7 +3507,6 @@ xfs_bmap_btalloc_at_eof( * Exact allocation failed. Reset to try an aligned allocation * according to the original allocation specification. */ - args->pag = NULL; args->alignment = stripe_align; args->minlen = nextminlen; args->minalignslop = 0;