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 0FBEB364C8 for ; Wed, 15 Nov 2023 19:46:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="U40D6OOR" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AF0A8C433C7; Wed, 15 Nov 2023 19:46:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1700077607; bh=kVsOrmYdArOt7f1QNAwmpu+shbEVATiShSdQb1MNUH0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=U40D6OORbQJfQ2OuqWOoV8cERKCV00YA1n9mQsjA0ClJ2/s4ih4I3VhuR8xOj4QPq 7DH40sOurg6NIMAo18+rUkhNXK1RnRxD6vZJQ3//U1WKOXXMqQFE0/Rjrf9PZFzeHd 9Whu6Qlr0IjX5dIKisUE/pc+1JwXWLG09ruwIBWQ= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Chao Yu , Gao Xiang , Sasha Levin Subject: [PATCH 6.6 407/603] erofs: fix erofs_insert_workgroup() lockref usage Date: Wed, 15 Nov 2023 14:15:52 -0500 Message-ID: <20231115191641.195932398@linuxfoundation.org> X-Mailer: git-send-email 2.42.1 In-Reply-To: <20231115191613.097702445@linuxfoundation.org> References: <20231115191613.097702445@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev 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: Gao Xiang [ Upstream commit 1a0ac8bd7a4fa5b2f4ef14c3b1e9d6e5a5faae06 ] As Linus pointed out [1], lockref_put_return() is fundamentally designed to be something that can fail. It behaves as a fastpath-only thing, and the failure case needs to be handled anyway. Actually, since the new pcluster was just allocated without being populated, it won't be accessed by others until it is inserted into XArray, so lockref helpers are actually unneeded here. Let's just set the proper reference count on initializing. [1] https://lore.kernel.org/r/CAHk-=whCga8BeQnJ3ZBh_Hfm9ctba_wpF444LpwRybVNMzO6Dw@mail.gmail.com Fixes: 7674a42f35ea ("erofs: use struct lockref to replace handcrafted approach") Reviewed-by: Chao Yu Link: https://lore.kernel.org/r/20231031060524.1103921-1-hsiangkao@linux.alibaba.com Signed-off-by: Gao Xiang Signed-off-by: Sasha Levin --- fs/erofs/utils.c | 8 +------- fs/erofs/zdata.c | 1 + 2 files changed, 2 insertions(+), 7 deletions(-) diff --git a/fs/erofs/utils.c b/fs/erofs/utils.c index cc6fb9e988991..4256a85719a1d 100644 --- a/fs/erofs/utils.c +++ b/fs/erofs/utils.c @@ -77,12 +77,7 @@ struct erofs_workgroup *erofs_insert_workgroup(struct super_block *sb, struct erofs_sb_info *const sbi = EROFS_SB(sb); struct erofs_workgroup *pre; - /* - * Bump up before making this visible to others for the XArray in order - * to avoid potential UAF without serialized by xa_lock. - */ - lockref_get(&grp->lockref); - + DBG_BUGON(grp->lockref.count < 1); repeat: xa_lock(&sbi->managed_pslots); pre = __xa_cmpxchg(&sbi->managed_pslots, grp->index, @@ -96,7 +91,6 @@ struct erofs_workgroup *erofs_insert_workgroup(struct super_block *sb, cond_resched(); goto repeat; } - lockref_put_return(&grp->lockref); grp = pre; } xa_unlock(&sbi->managed_pslots); diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c index 036f610e044b6..a7e6847f6f8f1 100644 --- a/fs/erofs/zdata.c +++ b/fs/erofs/zdata.c @@ -796,6 +796,7 @@ static int z_erofs_register_pcluster(struct z_erofs_decompress_frontend *fe) return PTR_ERR(pcl); spin_lock_init(&pcl->obj.lockref.lock); + pcl->obj.lockref.count = 1; /* one ref for this request */ pcl->algorithmformat = map->m_algorithmformat; pcl->length = 0; pcl->partial = true; -- 2.42.0