From nobody Mon Oct 9 23:19:12 2023 X-Original-To: dev-commits-src-all@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4S4FNK5lZ5z4wh1d; Mon, 9 Oct 2023 23:19:13 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "R3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4S4FNK46zmz3WFy; Mon, 9 Oct 2023 23:19:13 +0000 (UTC) (envelope-from git@FreeBSD.org) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1696893553; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=BskNqzehvXCGsDDDg8Onx5QMyApXPxNjaLznOhk9CVY=; b=x9H8dwIk2PeACu03MnPLPOTt4AlNnkVVxzIYIqIe2b2IVBKFAWlyvIHW7hBMt3idSO0T9e YDWkHw7JgxfzU5U3ZFbs1Awd4NUT0XqTH0Qhrze7so1dTqD6Kky8WstGveuZHEPeNl/hmh Oi0hSsam0jGcVqU734QKqA1a85PJyq4EzM8HPwS+0/EEScdthusb1vX5dNlGCC/d6XhRxD 8LS+FCFDezWzx4Zw/wvHOvYr6xl3/DcMlc7M270E+hqjMm38J1sZhTm8xcXDGvtw+aXwn5 PXeMPmvgU/6ZqI0mbq5sxmUh6TJhmyM1pmyGfOWUQMRP/tuHfgmWfC37/5Cdiw== ARC-Seal: i=1; s=dkim; d=freebsd.org; t=1696893553; a=rsa-sha256; cv=none; b=iF6IKVk7GDMoQCUXTRxpzLgMCwg4CKFHRpCieqel+wqCODyGa1OpWL62NIDTOEIzzplezx BZHQai62swX51jzVYPdWx8dL2geR0S42Bm20UjXBQuZLIpZbHiiFWbWcA36eI9J+jzJI5k 2prHsfA3LbTMjRCE7wn4WZrYdCpvyTQpLPtm0zCz5UqL4L2FyJea0uw1g3sT2BsWjNCiNh 4L88oeBsFsFG3e4exFpjjYRINBPkc4rSAuufzjIaf2Q6RjUwlOqUc/HSyqDZCgExasKhhv 2FExLOtwUA3ZE1yzGBUnXQZyeP4JAx97xpOiK7izUg4xmrCSITRDLCUb5MhGbQ== ARC-Authentication-Results: i=1; mx1.freebsd.org; none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1696893553; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=BskNqzehvXCGsDDDg8Onx5QMyApXPxNjaLznOhk9CVY=; b=q1Of9F8TnSkH8DOoxvuU4ttAwQGpKf+rpJNTsfcVk3UuNmX/aw5pWER/qD3AMBteVx1AdV PDIMwZbSdqzMs3Ksw5bwHth7uhDjjaR8AhGmCmYoH4Ni5LcFmghMqhqBaa8670NbLbQoyn W6dwwaGaMMmLSkVBiyEpOdmpqRZt6wcaUDteKfR011a/vIQB9SF1PYsHMXGhQypJ++c8/C OD7YdifzXq6QOB10l94Tu/errur4jdD3XrXHF8qaBZkar9IbRbDfe3gLCk50a2atvUxGwN IH8dp+Kk8EuPn8mXAoWtJDv2RjB05wyrOFP8oHldUiSlJoBV5+R+BZE+xlzdJQ== Received: from gitrepo.freebsd.org (gitrepo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:5]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 4S4FNK0kBHznC; Mon, 9 Oct 2023 23:19:13 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from gitrepo.freebsd.org ([127.0.1.44]) by gitrepo.freebsd.org (8.17.1/8.17.1) with ESMTP id 399NJCm6072746; Mon, 9 Oct 2023 23:19:12 GMT (envelope-from git@gitrepo.freebsd.org) Received: (from git@localhost) by gitrepo.freebsd.org (8.17.1/8.17.1/Submit) id 399NJC8L072743; Mon, 9 Oct 2023 23:19:12 GMT (envelope-from git) Date: Mon, 9 Oct 2023 23:19:12 GMT Message-Id: <202310092319.399NJC8L072743@gitrepo.freebsd.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org From: Mateusz Guzik Subject: git: b206bfb92c1f - stable/14 - vfs cache: plug a hypothetical corner case when freeing List-Id: Commit messages for all branches of the src repository List-Archive: https://lists.freebsd.org/archives/dev-commits-src-all List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-dev-commits-src-all@freebsd.org X-BeenThere: dev-commits-src-all@freebsd.org MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Git-Committer: mjg X-Git-Repository: src X-Git-Refname: refs/heads/stable/14 X-Git-Reftype: branch X-Git-Commit: b206bfb92c1f522c85ef1db44d42431e6c0d9334 Auto-Submitted: auto-generated The branch stable/14 has been updated by mjg: URL: https://cgit.FreeBSD.org/src/commit/?id=b206bfb92c1f522c85ef1db44d42431e6c0d9334 commit b206bfb92c1f522c85ef1db44d42431e6c0d9334 Author: Mateusz Guzik AuthorDate: 2023-09-23 02:04:06 +0000 Commit: Mateusz Guzik CommitDate: 2023-10-09 23:19:00 +0000 vfs cache: plug a hypothetical corner case when freeing cache_zap_unlocked_bucket is called with a bunch of addresses and without any locks held, forcing it to revalidate everything from scratch. It did not account for a case where the entry is reallocated with everything the same except for the target vnode. Should the target use a different lock than the one expected, freeing would proceed without being properly synchronized. Note this is almost impossible to happen in practice. (cherry picked from commit 0f15054f7990f9c772bea34778a8838aa05ebed8) --- sys/kern/vfs_cache.c | 25 ++++++++++++++++++------- 1 file changed, 18 insertions(+), 7 deletions(-) diff --git a/sys/kern/vfs_cache.c b/sys/kern/vfs_cache.c index 38a39331e237..44295e12ee59 100644 --- a/sys/kern/vfs_cache.c +++ b/sys/kern/vfs_cache.c @@ -1645,6 +1645,7 @@ cache_zap_unlocked_bucket(struct namecache *ncp, struct componentname *cnp, struct mtx *blp) { struct namecache *rncp; + struct mtx *rvlp; cache_assert_bucket_unlocked(ncp); @@ -1657,14 +1658,24 @@ cache_zap_unlocked_bucket(struct namecache *ncp, struct componentname *cnp, !bcmp(rncp->nc_name, cnp->cn_nameptr, rncp->nc_nlen)) break; } - if (rncp != NULL) { - cache_zap_locked(rncp); - mtx_unlock(blp); - cache_unlock_vnodes(dvlp, vlp); - atomic_add_long(&zap_bucket_relock_success, 1); - return (0); - } + if (rncp == NULL) + goto out_mismatch; + + if (!(ncp->nc_flag & NCF_NEGATIVE)) + rvlp = VP2VNODELOCK(rncp->nc_vp); + else + rvlp = NULL; + if (rvlp != vlp) + goto out_mismatch; + + cache_zap_locked(rncp); + mtx_unlock(blp); + cache_unlock_vnodes(dvlp, vlp); + atomic_add_long(&zap_bucket_relock_success, 1); + return (0); + +out_mismatch: mtx_unlock(blp); cache_unlock_vnodes(dvlp, vlp); return (EAGAIN);