From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 43082408614 for ; Mon, 24 Aug 2026 12:46:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787575571; cv=none; b=FlSIQYX5osnIa4hgeldGNNsGXp7K+llXxWlrZqcqkH2jHNHb51ZHtYFKiGcg4iHewQHzeGnGdm+XxuIsXtNAU/mLduISrVRUaQLG5CMqt87sxiGbIHWoDL+9MpYJoAXbh2901Nk5sxhPonwmkkRT1Fh16GtpUCcwXPqana1rv8o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787575571; c=relaxed/simple; bh=QXWIoSsvoLSJuEWBOM1kDzt8e3iGeCt/t3Tp7g15zKQ=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=lOvoK7XNP93yjvsojAQOR+7U8ybVrX1fMPUOvayDQrvZaCXU5QJPYVeh7zzfpok8lxQ5oshynJLe8iRIQMGOROOjNQyRkKj9j15UDp6mlIuZsqAK2c3AW8BrhWEjk41Qe4J+eesdvHpg2NcEWNqYyYU6EQkN3/xkrAm6pXBqEf4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=IEkJ0r8N; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="IEkJ0r8N" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1D7761F000E9; Mon, 24 Aug 2026 12:46:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787575569; bh=6B4zeReu69Rql46FLq/n6/HegngFjVMrpar8Ac7qB6A=; h=Subject:From:To:Cc:Date:In-Reply-To:References; b=IEkJ0r8N/XaEW9es4xAg/Sgiuukf2Fkgp+9WDqfgm45SjwX7KP+9mSU3FjuzzzFkV BE4Rh0ctPf9CC1e2tBzq0GBN+eXvjlSWna87lje0f/edjeOULh/Id/5cy3aqzfuNlQ M8nd+6iL7wF/J3NtVZhZYgJ6zHCRpiVUcaeLpT17HJFOZp6VrE1nb5IapKbcNM3QQr tBpcQLX6LqU2lDCM0oQhxspdl48yMf79R3o3BtxlIcq5hVKZzzvJEJW3V9FEjdgFSc DZuZ13BGy5RbspqcRLkU2wrmaIUVdcgtTbfT8hI8+KxlhU98LQxE2uyAmvxzRxdlUo cQhstV3v3+UUw== Message-ID: <40a5b6327dff9aaebb1cf07f75fbed692d4382f6.camel@kernel.org> Subject: Re: [PATCH v3 0/2] lockd: Fix two teardown races in the block retry loop From: Jeff Layton To: Chuck Lever , NeilBrown , Olga Kornievskaia , Dai Ngo , Tom Talpey , Trond Myklebust , Anna Schumaker Cc: linux-nfs@vger.kernel.org, Shuangpeng Bai , sashiko-bot Date: Mon, 24 Aug 2026 08:46:07 -0400 In-Reply-To: <20260822-lockd-retry-blocked-uaf-v3-0-761661eae60c@kernel.org> References: <20260822-lockd-retry-blocked-uaf-v3-0-761661eae60c@kernel.org> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV 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Sat, 2026-08-22 at 21:40 -0400, Chuck Lever wrote: > nlmsvc_retry_blocked() is the only path that operates on a block with > nlm_blocked_lock dropped. Both defects live in that window. Shuangpeng > Bai's KASAN report catches one of them, a block freed while the retry > is still using it. sashiko-bot flagged the other while reviewing v1. > The retry re-queues a block that the teardown scan has already > retired, so the host that block pins is never reaped. >=20 > Patch 1 fixes the first and applies without patch 2, so it can be > backported on its own. Patch 2 is meant for mainline only. The race > it closes leaks a host, and closing it widens the f_mutex hold across > the retry loop. >=20 > v2 added a B_DEAD flag that makes nlmsvc_insert_block() refuse to > queue a retired block. That appeared to repair the second race, but > it doesn't work. Every caller relies on that insert to take the list > reference, so a refused insert lets nlmsvc_grant_blocked() drop the > last reference to a block whose file_lock the VFS still has queued > on a blocker. >=20 > Signed-off-by: Chuck Lever >=20 > --- > Changes in v3: > - Split the fix in two. Patch 1 is the block reference alone. > - Drop B_DEAD. A refused insert could free a live block (sashiko-bot). > - Serialize the retry against nlmsvc_traverse_blocks() with f_mutex. > - Link to v2: https://lore.kernel.org/r/20260820150831.3291262-1-cel@kern= el.org >=20 > Changes in v2: > - Add B_DEAD so a retry cannot requeue a retired block (sashiko-bot). > - Link to v1: https://lore.kernel.org/r/20260819162247.2970703-1-cel@kern= el.org >=20 > --- > Chuck Lever (2): > lockd: Fix use-after-free in nlmsvc_retry_blocked > lockd: Serialize block retries against host teardown >=20 > fs/lockd/svclock.c | 33 ++++++++++++++++++++++++++++++--- > 1 file changed, 30 insertions(+), 3 deletions(-) > --- > base-commit: 01c2994ccb0197cb44b0db89aacab460110f6347 > change-id: 20260820-lockd-retry-blocked-uaf-68f6b50098d9 >=20 > Best regards, > -- =20 > Chuck Lever Reviewed-by: Jeff Layton