From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id CDFEBE7C4EB for ; Wed, 4 Oct 2023 18:35:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243842AbjJDSfd (ORCPT ); Wed, 4 Oct 2023 14:35:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41674 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244428AbjJDSfc (ORCPT ); Wed, 4 Oct 2023 14:35:32 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C596AA6 for ; Wed, 4 Oct 2023 11:35:29 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1917BC433C8; Wed, 4 Oct 2023 18:35:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1696444529; bh=SUN/8AuC+61EsOVe1SUTgyEKj12/nvDCGIZuNjfMpKY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=1lixKfgPOp3mw4yRTrtVH1CJ4IilcJNcVMiZcD6+7oT6naRwFpB55jyKDFQDBQozp VCgAkMJPBz8lFro2TcTWm2bNBAcpBidi5PXhL6lXp7HRPo2kLD9AMzHUGzj/ZeLNnd QC0kGmbaf3W7NZc/KLdafdKlcGMQpoF2D7LcxknM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Rafael Aquini , Waiman Long , Vlastimil Babka Subject: [PATCH 6.5 283/321] mm/slab_common: fix slab_caches list corruption after kmem_cache_destroy() Date: Wed, 4 Oct 2023 19:57:08 +0200 Message-ID: <20231004175242.382701667@linuxfoundation.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20231004175229.211487444@linuxfoundation.org> References: <20231004175229.211487444@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 6.5-stable review patch. If anyone has any objections, please let me know. ------------------ From: Rafael Aquini commit 46a9ea6681907a3be6b6b0d43776dccc62cad6cf upstream. After the commit in Fixes:, if a module that created a slab cache does not release all of its allocated objects before destroying the cache (at rmmod time), we might end up releasing the kmem_cache object without removing it from the slab_caches list thus corrupting the list as kmem_cache_destroy() ignores the return value from shutdown_cache(), which in turn never removes the kmem_cache object from slabs_list in case __kmem_cache_shutdown() fails to release all of the cache's slabs. This is easily observable on a kernel built with CONFIG_DEBUG_LIST=y as after that ill release the system will immediately trip on list_add, or list_del, assertions similar to the one shown below as soon as another kmem_cache gets created, or destroyed: [ 1041.213632] list_del corruption. next->prev should be ffff89f596fb5768, but was 52f1e5016aeee75d. (next=ffff89f595a1b268) [ 1041.219165] ------------[ cut here ]------------ [ 1041.221517] kernel BUG at lib/list_debug.c:62! [ 1041.223452] invalid opcode: 0000 [#1] PREEMPT SMP PTI [ 1041.225408] CPU: 2 PID: 1852 Comm: rmmod Kdump: loaded Tainted: G B W OE 6.5.0 #15 [ 1041.228244] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS edk2-20230524-3.fc37 05/24/2023 [ 1041.231212] RIP: 0010:__list_del_entry_valid+0xae/0xb0 Another quick way to trigger this issue, in a kernel with CONFIG_SLUB=y, is to set slub_debug to poison the released objects and then just run cat /proc/slabinfo after removing the module that leaks slab objects, in which case the kernel will panic: [ 50.954843] general protection fault, probably for non-canonical address 0xa56b6b6b6b6b6b8b: 0000 [#1] PREEMPT SMP PTI [ 50.961545] CPU: 2 PID: 1495 Comm: cat Kdump: loaded Tainted: G B W OE 6.5.0 #15 [ 50.966808] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS edk2-20230524-3.fc37 05/24/2023 [ 50.972663] RIP: 0010:get_slabinfo+0x42/0xf0 This patch fixes this issue by properly checking shutdown_cache()'s return value before taking the kmem_cache_release() branch. Fixes: 0495e337b703 ("mm/slab_common: Deleting kobject in kmem_cache_destroy() without holding slab_mutex/cpu_hotplug_lock") Signed-off-by: Rafael Aquini Cc: stable@vger.kernel.org Reviewed-by: Waiman Long Signed-off-by: Vlastimil Babka Signed-off-by: Greg Kroah-Hartman --- mm/slab_common.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -479,7 +479,7 @@ void slab_kmem_cache_release(struct kmem void kmem_cache_destroy(struct kmem_cache *s) { - int refcnt; + int err = -EBUSY; bool rcu_set; if (unlikely(!s) || !kasan_check_byte(s)) @@ -490,17 +490,17 @@ void kmem_cache_destroy(struct kmem_cach rcu_set = s->flags & SLAB_TYPESAFE_BY_RCU; - refcnt = --s->refcount; - if (refcnt) + s->refcount--; + if (s->refcount) goto out_unlock; - WARN(shutdown_cache(s), - "%s %s: Slab cache still has objects when called from %pS", + err = shutdown_cache(s); + WARN(err, "%s %s: Slab cache still has objects when called from %pS", __func__, s->name, (void *)_RET_IP_); out_unlock: mutex_unlock(&slab_mutex); cpus_read_unlock(); - if (!refcnt && !rcu_set) + if (!err && !rcu_set) kmem_cache_release(s); } EXPORT_SYMBOL(kmem_cache_destroy);