From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cn.fujitsu.com ([59.151.112.132]:50136 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1755177AbdC3GdB (ORCPT ); Thu, 30 Mar 2017 02:33:01 -0400 From: Qu Wenruo To: CC: Subject: [PATCH v4 5/5] btrfs: Prevent scrub recheck from racing with dev replace Date: Thu, 30 Mar 2017 14:32:51 +0800 Message-ID: <20170330063251.16872-6-quwenruo@cn.fujitsu.com> In-Reply-To: <20170330063251.16872-1-quwenruo@cn.fujitsu.com> References: <20170330063251.16872-1-quwenruo@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-btrfs-owner@vger.kernel.org List-ID: scrub_setup_recheck_block() calls btrfs_map_sblock() and then accesses bbio without protection of bio_counter. This can lead to use-after-free if racing with dev replace cancel. Fix it by increasing bio_counter before calling btrfs_map_sblock() and decreasing the bio_counter when corresponding recover is finished. Reported-by: Liu Bo Signed-off-by: Qu Wenruo Reviewed-by: Liu Bo --- fs/btrfs/scrub.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c index 5720ecdad5d7..928db379a09b 100644 --- a/fs/btrfs/scrub.c +++ b/fs/btrfs/scrub.c @@ -1077,9 +1077,11 @@ static inline void scrub_get_recover(struct scrub_recover *recover) atomic_inc(&recover->refs); } -static inline void scrub_put_recover(struct scrub_recover *recover) +static inline void scrub_put_recover(struct btrfs_fs_info *fs_info, + struct scrub_recover *recover) { if (atomic_dec_and_test(&recover->refs)) { + btrfs_bio_counter_dec(fs_info); btrfs_put_bbio(recover->bbio); kfree(recover); } @@ -1478,7 +1480,7 @@ static int scrub_handle_errored_block(struct scrub_block *sblock_to_check) sblock->pagev[page_index]->sblock = NULL; recover = sblock->pagev[page_index]->recover; if (recover) { - scrub_put_recover(recover); + scrub_put_recover(fs_info, recover); sblock->pagev[page_index]->recover = NULL; } @@ -1570,16 +1572,19 @@ static int scrub_setup_recheck_block(struct scrub_block *original_sblock, * with a length of PAGE_SIZE, each returned stripe * represents one mirror */ + btrfs_bio_counter_inc_blocked(fs_info); ret = btrfs_map_sblock(fs_info, BTRFS_MAP_GET_READ_MIRRORS, logical, &mapped_length, &bbio, 0, 1); if (ret || !bbio || mapped_length < sublen) { btrfs_put_bbio(bbio); + btrfs_bio_counter_dec(fs_info); return -EIO; } recover = kzalloc(sizeof(struct scrub_recover), GFP_NOFS); if (!recover) { btrfs_put_bbio(bbio); + btrfs_bio_counter_dec(fs_info); return -ENOMEM; } @@ -1605,7 +1610,7 @@ static int scrub_setup_recheck_block(struct scrub_block *original_sblock, spin_lock(&sctx->stat_lock); sctx->stat.malloc_errors++; spin_unlock(&sctx->stat_lock); - scrub_put_recover(recover); + scrub_put_recover(fs_info, recover); return -ENOMEM; } scrub_page_get(page); @@ -1647,7 +1652,7 @@ static int scrub_setup_recheck_block(struct scrub_block *original_sblock, scrub_get_recover(recover); page->recover = recover; } - scrub_put_recover(recover); + scrub_put_recover(fs_info, recover); length -= sublen; logical += sublen; page_index++; -- 2.12.1