From patchwork Mon Mar 7 22:48:21 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kamal Mostafa X-Patchwork-Id: 594184 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) by ozlabs.org (Postfix) with ESMTP id 16A7D140C0A; Wed, 9 Mar 2016 00:05:55 +1100 (AEDT) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1adHKh-0006NA-1z; Tue, 08 Mar 2016 13:05:51 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.76) (envelope-from ) id 1ad41l-00088q-SF for kernel-team@lists.ubuntu.com; Mon, 07 Mar 2016 22:53:25 +0000 Received: from 1.general.kamal.us.vpn ([10.172.68.52] helo=fourier) by youngberry.canonical.com with esmtpsa (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.76) (envelope-from ) id 1ad41l-0000GZ-80; Mon, 07 Mar 2016 22:53:25 +0000 Received: from kamal by fourier with local (Exim 4.86) (envelope-from ) id 1ad41i-0001yR-Il; Mon, 07 Mar 2016 14:53:22 -0800 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Subject: [PATCH 4.2.y-ckt 110/273] radix-tree: fix oops after radix_tree_iter_retry Date: Mon, 7 Mar 2016 14:48:21 -0800 Message-Id: <1457391064-6660-111-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 2.7.0 In-Reply-To: <1457391064-6660-1-git-send-email-kamal@canonical.com> References: <1457391064-6660-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 4.2 X-Mailman-Approved-At: Tue, 08 Mar 2016 13:05:01 +0000 Cc: Ohad Ben-Cohen , Kamal Mostafa , Hugh Dickins , Matthew Wilcox , Andrew Morton , Linus Torvalds , Jeremiah Mahler , Konstantin Khlebnikov X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.14 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: kernel-team-bounces@lists.ubuntu.com 4.2.8-ckt5 -stable review patch. If anyone has any objections, please let me know. ---8<------------------------------------------------------------ From: Konstantin Khlebnikov commit 732042821cfa106b3c20b9780e4c60fee9d68900 upstream. Helper radix_tree_iter_retry() resets next_index to the current index. In following radix_tree_next_slot current chunk size becomes zero. This isn't checked and it tries to dereference null pointer in slot. Tagged iterator is fine because retry happens only at slot 0 where tag bitmask in iter->tags is filled with single bit. Fixes: 46437f9a554f ("radix-tree: fix race in gang lookup") Signed-off-by: Konstantin Khlebnikov Cc: Matthew Wilcox Cc: Hugh Dickins Cc: Ohad Ben-Cohen Cc: Jeremiah Mahler Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Kamal Mostafa --- include/linux/radix-tree.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h index 1a2b227..5d5174b 100644 --- a/include/linux/radix-tree.h +++ b/include/linux/radix-tree.h @@ -391,7 +391,7 @@ void **radix_tree_iter_retry(struct radix_tree_iter *iter) * @iter: pointer to radix tree iterator * Returns: current chunk size */ -static __always_inline unsigned +static __always_inline long radix_tree_chunk_size(struct radix_tree_iter *iter) { return iter->next_index - iter->index; @@ -425,9 +425,9 @@ radix_tree_next_slot(void **slot, struct radix_tree_iter *iter, unsigned flags) return slot + offset + 1; } } else { - unsigned size = radix_tree_chunk_size(iter) - 1; + long size = radix_tree_chunk_size(iter); - while (size--) { + while (--size > 0) { slot++; iter->index++; if (likely(*slot))