From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5CBFC4C3C3; Mon, 1 Apr 2024 16:52:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711990322; cv=none; b=Nzf7MfTsB2TrSVfrFxUyZJ7a5Cd/D2Zmz5FwvU5hyxHjtd/Fw4CP6YDAcef4ckrLe/zvirVPvxizctpwaPCDsnxBbIeEh4xGAysP4lflcA8H8vO3FXlxSt7CBQUSLvTTvaAtYD0Ju7XfnhderFlzlZiMWy+3FmTqW/7mnaix2so= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711990322; c=relaxed/simple; bh=zopiP55Y84kF58HNp0CfzqcAQNNHkPjfkjns0Q0QAp0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=sKzJZHiIinqbicpdzybSVg5KynkqfNJ6FMs0oIHQG2idhY3gflpkb7kNpuTR/z0w/A8Xn2pPxpSpc+XicDFK8n61Xdi+7Qj3tZIL/qrF7c3iN/69az/+XYACNfVWKU7Mo6qAVk/5eiwRorb1K6IyjmNFSU55HKAGzvNNcpXNMfY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=owv5ie3q; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="owv5ie3q" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 897E9C433C7; Mon, 1 Apr 2024 16:52:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1711990321; bh=zopiP55Y84kF58HNp0CfzqcAQNNHkPjfkjns0Q0QAp0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=owv5ie3qkM97yWsjg74WiZ24c9ICNJr/lB9QYNLh90OivbndLDh6PsCJOaFz+0k3e zdK/D/edLYefGY6Ii0Tl8XSsOpzezuHgIAZiL3SMQHmjRANkP3Ea0AIByc3jAH4nXp hl6A385sVDKbCSsN4AqUMpAvCrLt3fPzNyMbQPz0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Carlos Maiolino , Ubisectech Sirius , Jan Kara , Hugh Dickins , Andrew Morton Subject: [PATCH 6.6 316/396] tmpfs: fix race on handling dquot rbtree Date: Mon, 1 Apr 2024 17:46:05 +0200 Message-ID: <20240401152557.334682321@linuxfoundation.org> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20240401152547.867452742@linuxfoundation.org> References: <20240401152547.867452742@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Carlos Maiolino commit 0a69b6b3a026543bc215ccc866d0aea5579e6ce2 upstream. A syzkaller reproducer found a race while attempting to remove dquot information from the rb tree. Fetching the rb_tree root node must also be protected by the dqopt->dqio_sem, otherwise, giving the right timing, shmem_release_dquot() will trigger a warning because it couldn't find a node in the tree, when the real reason was the root node changing before the search starts: Thread 1 Thread 2 - shmem_release_dquot() - shmem_{acquire,release}_dquot() - fetch ROOT - Fetch ROOT - acquire dqio_sem - wait dqio_sem - do something, triger a tree rebalance - release dqio_sem - acquire dqio_sem - start searching for the node, but from the wrong location, missing the node, and triggering a warning. Link: https://lkml.kernel.org/r/20240320124011.398847-1-cem@kernel.org Fixes: eafc474e2029 ("shmem: prepare shmem quota infrastructure") Signed-off-by: Carlos Maiolino Reported-by: Ubisectech Sirius Reviewed-by: Jan Kara Cc: Hugh Dickins Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- mm/shmem_quota.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/mm/shmem_quota.c b/mm/shmem_quota.c index 062d1c1097ae..ce514e700d2f 100644 --- a/mm/shmem_quota.c +++ b/mm/shmem_quota.c @@ -116,7 +116,7 @@ static int shmem_free_file_info(struct super_block *sb, int type) static int shmem_get_next_id(struct super_block *sb, struct kqid *qid) { struct mem_dqinfo *info = sb_dqinfo(sb, qid->type); - struct rb_node *node = ((struct rb_root *)info->dqi_priv)->rb_node; + struct rb_node *node; qid_t id = from_kqid(&init_user_ns, *qid); struct quota_info *dqopt = sb_dqopt(sb); struct quota_id *entry = NULL; @@ -126,6 +126,7 @@ static int shmem_get_next_id(struct super_block *sb, struct kqid *qid) return -ESRCH; down_read(&dqopt->dqio_sem); + node = ((struct rb_root *)info->dqi_priv)->rb_node; while (node) { entry = rb_entry(node, struct quota_id, node); @@ -165,7 +166,7 @@ static int shmem_get_next_id(struct super_block *sb, struct kqid *qid) static int shmem_acquire_dquot(struct dquot *dquot) { struct mem_dqinfo *info = sb_dqinfo(dquot->dq_sb, dquot->dq_id.type); - struct rb_node **n = &((struct rb_root *)info->dqi_priv)->rb_node; + struct rb_node **n; struct shmem_sb_info *sbinfo = dquot->dq_sb->s_fs_info; struct rb_node *parent = NULL, *new_node = NULL; struct quota_id *new_entry, *entry; @@ -176,6 +177,8 @@ static int shmem_acquire_dquot(struct dquot *dquot) mutex_lock(&dquot->dq_lock); down_write(&dqopt->dqio_sem); + n = &((struct rb_root *)info->dqi_priv)->rb_node; + while (*n) { parent = *n; entry = rb_entry(parent, struct quota_id, node); @@ -264,7 +267,7 @@ static bool shmem_is_empty_dquot(struct dquot *dquot) static int shmem_release_dquot(struct dquot *dquot) { struct mem_dqinfo *info = sb_dqinfo(dquot->dq_sb, dquot->dq_id.type); - struct rb_node *node = ((struct rb_root *)info->dqi_priv)->rb_node; + struct rb_node *node; qid_t id = from_kqid(&init_user_ns, dquot->dq_id); struct quota_info *dqopt = sb_dqopt(dquot->dq_sb); struct quota_id *entry = NULL; @@ -275,6 +278,7 @@ static int shmem_release_dquot(struct dquot *dquot) goto out_dqlock; down_write(&dqopt->dqio_sem); + node = ((struct rb_root *)info->dqi_priv)->rb_node; while (node) { entry = rb_entry(node, struct quota_id, node); -- 2.44.0