From nobody Thu Oct 5 12:44:49 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 4S1WV93fL9z4wZgy; Thu, 5 Oct 2023 12:44:49 +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 4S1WV92yV4z4CnP; Thu, 5 Oct 2023 12:44:49 +0000 (UTC) (envelope-from git@FreeBSD.org) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1696509889; 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=iQzMiGgRG7J9kC5BX1focLPzktVQ90DQ6UJSn0WxEr8=; b=FE0dkaWBWpFdziAKM+PLQbjJFzVTbbYAfzBq0Vbu0RRtybpIg7q+wgWu71OuL/NPzhXeix Wyu9YkCgOLsstfvE1sICVWT1fjGyiIKUZM3A7DpOdJ6WRr6jsU7pJHGZDqKYuzkZxpwY7m paYLKy79bWW0rW2xpfQF4wsAD/G12NutiaH1jqxQlm/KO8LVkUrCjaOZ2jEx3iIw6Qb1ax iMUs7lcmPJIT+7oAcxTox2hCI1FzAy3z4A1yZ6ldm6xz5Jdd5wvtM/lu/nWEp03iK2uSPn 6zkX8+juThdsWqlN6TQz2qpCjDUaJWm5fWG6n4LgVmyBXiJdQ+2jRi+DzbfRAw== ARC-Seal: i=1; s=dkim; d=freebsd.org; t=1696509889; a=rsa-sha256; cv=none; b=r2YAzKHqqdhgCRWpDUVyEdXW8oJptScKNRkA0aCbZhpgNV8g0LAFkJ1OXpU2ty9Xs+XBAh Vv1Zb7Y2BkxoQ6virqY30wHQDbIh4igLuFr5aD8I3D45gfeStDpOzscfigHbI/kW34vUrT VpmsN9vYQGxQR90fqpxBh0l39U7Vs4vnrOao6NHG6qHACCmYI7Exyo15cBwNdVT/guF7Zl 96M6WMq4QuVbeTGg6vWvMeLE15aMURS4XLdU1wlkF8wt6pg2wDbEp82UdAg6/ErqnSHR9h aiVxHeCghcIadOpGDBqFwud1oJPxiuglP2hQQsVa//i4dRO8+m2fDjTHTAmAMA== 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=1696509889; 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=iQzMiGgRG7J9kC5BX1focLPzktVQ90DQ6UJSn0WxEr8=; b=JpcahhnsqW8TdPuQrPIcOfeXxzmW5T7Q4jjr2QesojYa+5U/Na+qJhG3NCaQ96LPYp1ZBL Gtwnr/kgOzl+O15yRja9a4S54NT0lCb3sEiFv21pYxdbT+bcQDLy4+BJPoKqALRDaz/7VC KC3lppDMkBk4xl6RLpVQbzhJaGXleOiG/P5Wo9ccIXeSa+EHU50Uqwe3zeafnLKgkeZq2B PX6vLoXjrT7/U5cJyDfkSGH1vs+uglq3YNEA9+lzcyM2dbc3LnN2h7m1ZMPQv0xsVvdmFL Px+6jX5ERaKVC6/AX2rrqUZW9vNckQjXzYEQncPTilArkFrDjk/2xHeZHGGQ2Q== 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 4S1WV922hPz1KR0; Thu, 5 Oct 2023 12:44:49 +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 395Cinsn027410; Thu, 5 Oct 2023 12:44:49 GMT (envelope-from git@gitrepo.freebsd.org) Received: (from git@localhost) by gitrepo.freebsd.org (8.17.1/8.17.1/Submit) id 395Cin3k027407; Thu, 5 Oct 2023 12:44:49 GMT (envelope-from git) Date: Thu, 5 Oct 2023 12:44:49 GMT Message-Id: <202310051244.395Cin3k027407@gitrepo.freebsd.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org From: Mateusz Guzik Subject: git: 0f15054f7990 - main - 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/main X-Git-Reftype: branch X-Git-Commit: 0f15054f7990f9c772bea34778a8838aa05ebed8 Auto-Submitted: auto-generated The branch main has been updated by mjg: URL: https://cgit.FreeBSD.org/src/commit/?id=0f15054f7990f9c772bea34778a8838aa05ebed8 commit 0f15054f7990f9c772bea34778a8838aa05ebed8 Author: Mateusz Guzik AuthorDate: 2023-09-23 02:04:06 +0000 Commit: Mateusz Guzik CommitDate: 2023-10-05 12:44:42 +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. --- 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 00632716a2ec..560ff7d441c0 100644 --- a/sys/kern/vfs_cache.c +++ b/sys/kern/vfs_cache.c @@ -1720,6 +1720,7 @@ cache_zap_unlocked_bucket(struct namecache *ncp, struct componentname *cnp, struct mtx *blp) { struct namecache *rncp; + struct mtx *rvlp; cache_assert_bucket_unlocked(ncp); @@ -1732,14 +1733,24 @@ 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);