From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751596AbdITGCf (ORCPT ); Wed, 20 Sep 2017 02:02:35 -0400 Received: from LGEAMRELO13.lge.com ([156.147.23.53]:48139 "EHLO lgeamrelo13.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751547AbdITGCd (ORCPT ); Wed, 20 Sep 2017 02:02:33 -0400 X-Original-SENDERIP: 156.147.1.125 X-Original-MAILFROM: minchan@kernel.org X-Original-SENDERIP: 10.177.220.163 X-Original-MAILFROM: minchan@kernel.org From: Minchan Kim To: Andrew Morton Cc: linux-kernel@vger.kernel.org, kernel-team , Minchan Kim , Sergey Senozhatsky Subject: [PATCH v2] zram: fix null dereference of handle Date: Wed, 20 Sep 2017 15:02:27 +0900 Message-Id: <1505887347-10881-1-git-send-email-minchan@kernel.org> X-Mailer: git-send-email 2.7.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org For the testing, I found handle passed to zs_map_object in __zram_bvec_read is NULL so that kernel goes the Oops by pin_object. The reason is there is no routine to check the slot's freeing after getting the slot's lock. This patch fixes it. * From v1: * remove unlikely branch - Sergey * In !handle case, use 0 instead of zram_get_element - Sergey Fixes: 1f7319c74275 ("zram: partial IO refactoring") Cc: Sergey Senozhatsky Signed-off-by: Minchan Kim --- drivers/block/zram/zram_drv.c | 36 ++++++++++++------------------------ 1 file changed, 12 insertions(+), 24 deletions(-) diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 2981c27d3aae..f149d3e61234 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -766,27 +766,6 @@ static void zram_slot_unlock(struct zram *zram, u32 index) bit_spin_unlock(ZRAM_ACCESS, &zram->table[index].value); } -static bool zram_same_page_read(struct zram *zram, u32 index, - struct page *page, - unsigned int offset, unsigned int len) -{ - zram_slot_lock(zram, index); - if (unlikely(!zram_get_handle(zram, index) || - zram_test_flag(zram, index, ZRAM_SAME))) { - void *mem; - - zram_slot_unlock(zram, index); - mem = kmap_atomic(page); - zram_fill_page(mem + offset, len, - zram_get_element(zram, index)); - kunmap_atomic(mem); - return true; - } - zram_slot_unlock(zram, index); - - return false; -} - static void zram_meta_free(struct zram *zram, u64 disksize) { size_t num_pages = disksize >> PAGE_SHIFT; @@ -884,11 +863,20 @@ static int __zram_bvec_read(struct zram *zram, struct page *page, u32 index, zram_slot_unlock(zram, index); } - if (zram_same_page_read(zram, index, page, 0, PAGE_SIZE)) - return 0; - zram_slot_lock(zram, index); handle = zram_get_handle(zram, index); + if (!handle || zram_test_flag(zram, index, ZRAM_SAME)) { + unsigned long value; + void *mem; + + value = handle ? zram_get_element(zram, index) : 0; + mem = kmap_atomic(page); + zram_fill_page(mem, PAGE_SIZE, value); + kunmap_atomic(mem); + zram_slot_unlock(zram, index); + return 0; + } + size = zram_get_obj_size(zram, index); src = zs_map_object(zram->mem_pool, handle, ZS_MM_RO); -- 2.7.4