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a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1650638765; h=from:from:sender:sender: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:list-id:list-help: list-unsubscribe:list-subscribe:list-post; bh=Lp6qJegCpT2hAvPxY7Xfepnh4izaKQTfZEjj1HCCs+E=; b=jGBm3Mn+5m3JZVIbJWZoQzQGOXOtJKwkFynaQg4K1dcJz1rKBvzyJM8DoWYV3ZXuSpPXC9 28L9gxaBef4gmaQBvynfpIOFWA6mLZdQEnEKAx/NgsffhKzk+4D3mYJZCcA5gxUXi/FG4f duEDXne8bHu2mcyGYAVhRauyJjE6NLU= X-MC-Unique: heJJrOngOoGbJuIMop-ULQ-1 X-Original-To: libvir-list@listman.corp.redhat.com From: Michal Privoznik To: libvir-list@redhat.com Subject: [PATCH] nwfilter_driver: Make reload fail if racing with stateCleanup() Date: Fri, 22 Apr 2022 16:45:37 +0200 Message-Id: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.85 on 10.11.54.10 X-BeenThere: libvir-list@redhat.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: Development discussions about the libvirt library & tools List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: libvir-list-bounces@redhat.com Sender: "libvir-list" X-Scanned-By: MIMEDefang 2.84 on 10.11.54.1 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=libvir-list-bounces@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1650638766281100001 Content-Type: text/plain; charset="utf-8"; x-default="true" When one thread is trying to reload NWFilter driver (by running nwfilterStateReload()) but there's another thread that's concurrently running nwfilterStateCleanup() a crash may occur. This is despite nwfilterStateReload() checking for driver !=3D NULL, because is done so without @driverMutex held. A typical TOCTOU. Fortunately, the mutex is always initialized, so the mutex can be acquired at all times and @driver can be checked with the lock held. Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=3D2075837 Signed-off-by: Michal Privoznik --- src/nwfilter/nwfilter_driver.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/src/nwfilter/nwfilter_driver.c b/src/nwfilter/nwfilter_driver.c index b66ba22737..d028efafbe 100644 --- a/src/nwfilter/nwfilter_driver.c +++ b/src/nwfilter/nwfilter_driver.c @@ -309,6 +309,8 @@ nwfilterStateInitialize(bool privileged, static int nwfilterStateReload(void) { + VIR_LOCK_GUARD lock =3D virLockGuardLock(&driverMutex); + if (!driver) return -1; =20 @@ -319,15 +321,13 @@ nwfilterStateReload(void) /* shut down all threads -- they will be restarted if necessary */ virNWFilterLearnThreadsTerminate(true); =20 - VIR_WITH_MUTEX_LOCK_GUARD(&driverMutex) { - VIR_WITH_MUTEX_LOCK_GUARD(&driver->updateLock) { - virNWFilterObjListLoadAllConfigs(driver->nwfilters, driver->co= nfigDir); - } - - - virNWFilterBuildAll(driver, false); + VIR_WITH_MUTEX_LOCK_GUARD(&driver->updateLock) { + virNWFilterObjListLoadAllConfigs(driver->nwfilters, driver->config= Dir); } =20 + + virNWFilterBuildAll(driver, false); + return 0; } =20 --=20 2.35.1