From nobody Fri Oct 13 23:53:49 2023 X-Original-To: dev-commits-src-branches@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 4S6jyQ09Qqz4wy36; Fri, 13 Oct 2023 23:53:50 +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 4S6jyP6rcNz3JlD; Fri, 13 Oct 2023 23:53:49 +0000 (UTC) (envelope-from git@FreeBSD.org) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1697241230; 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=1XjwQQk8zw1GRmeP8oDGyC8sZ4T/M7tDVMuk2cUCOZA=; b=mCVyRFxGnWPobAGddv8G9AvWZ1BYjQrie73jYtufMYV5L4Nq1uozv3O4VPmNtwoLNL3+aW ssfdp2OHeFncEiZ5Uo6StG9Ocp5YettlyOoxSR7mDveTtFqZWmlpa8Z8olk8vG+k1oRqa4 uFRhxmsVyvVdAd4Z6x4kYpyrQWmBIIZQ69w+6jsTNwQPNEbntZGaVsffEJyZtJ6ZjMcH8B EwSsCVyt6kSUlfegdsYAgBuGXQkhbUQdsermsCDCQ1IWJorPk5wMS4uKJLCtfW68AuiUdB 9arDKCa/sOko9zZBWZDe249sT+fSjH1VcKmiUW9sEmVI2hc+6x829P4Gwe23PA== ARC-Seal: i=1; s=dkim; d=freebsd.org; t=1697241230; a=rsa-sha256; cv=none; b=hV0wL2KZz7vAi5qjovT4Hwgiw/dM1et5d21pjfpwCB1hLZb9mH5J29s0C1SJ1hCLNuNaGq 9PrOy13zPyTgh/8TLYpT/1wxzEscV2MxJKDrFS1zBF9pdEgdq450wgZNrd4tl2oQfi5u7K 7iVPudPvNAaQ59mmj40/sAI/5KiMXKN6jV+OOoyXPK2b+mQETGQYwovGv7/4tnC0/2kGAj GgYF1gNalwOtRz2PzHEX0kTK5B+T4INj1KzAN+RV4lC24o5c7riSUaLIr+IJ0r3vYcaohJ Pp9Q0IB01zjmo2R7T6BIeqs3lmz7MqNkhDnjp/osvn6m5mhMLV63ZA6Fe10iyw== 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=1697241230; 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=1XjwQQk8zw1GRmeP8oDGyC8sZ4T/M7tDVMuk2cUCOZA=; b=tp7JoOxXgcn4IJbF0iqpeNe6+66qxWUNCCS5ev/U6Y2rUOVQk2i51U8XzeyabziCnU6WOo Q/En+yVkZmUgVlEh2OKD3lcmwxG54NgpQkWDGQ1CLAfy5k3htZ9Src6qSmO72Pqekzjvtu z/pvBJuHJJ7u2WV4BmKjq1UbQ3b9lXww+I9zYtrhkevFEZ3XXALC7HRh1CueuBkOX6RwsE nlWZ3PCqOhfrIPUp9WmNrka+XSZqAq5i1DvBEAiIUu8fXfesAxgvpy4biKFzp9Phc0v+qM T6ChIwa85Pb4Ovi7GEN2sMXt9kYLLSH1pnjQzswJwzJpKYrUiU7LIIZ3OgPT4g== 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 4S6jyP5yYLz17Vp; Fri, 13 Oct 2023 23:53:49 +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 39DNrnuu032004; Fri, 13 Oct 2023 23:53:49 GMT (envelope-from git@gitrepo.freebsd.org) Received: (from git@localhost) by gitrepo.freebsd.org (8.17.1/8.17.1/Submit) id 39DNrnt9032001; Fri, 13 Oct 2023 23:53:49 GMT (envelope-from git) Date: Fri, 13 Oct 2023 23:53:49 GMT Message-Id: <202310132353.39DNrnt9032001@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: c3dc958cacd8 - stable/13 - vfs cache: plug a hypothetical corner case when freeing List-Id: Commits to the stable branches of the FreeBSD src repository List-Archive: https://lists.freebsd.org/archives/dev-commits-src-branches List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-dev-commits-src-branches@freebsd.org X-BeenThere: dev-commits-src-branches@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/13 X-Git-Reftype: branch X-Git-Commit: c3dc958cacd819c9fe989477371f01c187873cc0 Auto-Submitted: auto-generated The branch stable/13 has been updated by mjg: URL: https://cgit.FreeBSD.org/src/commit/?id=c3dc958cacd819c9fe989477371f01c187873cc0 commit c3dc958cacd819c9fe989477371f01c187873cc0 Author: Mateusz Guzik AuthorDate: 2023-09-23 02:04:06 +0000 Commit: Mateusz Guzik CommitDate: 2023-10-13 23:48:12 +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 1d52b2e63169..49e66803a1d1 100644 --- a/sys/kern/vfs_cache.c +++ b/sys/kern/vfs_cache.c @@ -1649,6 +1649,7 @@ cache_zap_unlocked_bucket(struct namecache *ncp, struct componentname *cnp, struct mtx *blp) { struct namecache *rncp; + struct mtx *rvlp; cache_assert_bucket_unlocked(ncp); @@ -1661,14 +1662,24 @@ 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);