From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from userp1040.oracle.com ([156.151.31.81]:24531 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751087AbcFRCNP (ORCPT ); Fri, 17 Jun 2016 22:13:15 -0400 From: Liu Bo To: linux-btrfs@vger.kernel.org Cc: David Sterba Subject: [PATCH] Btrfs: fix error handling in map_private_extent_buffer Date: Fri, 17 Jun 2016 19:16:21 -0700 Message-Id: <1466216181-1555-1-git-send-email-bo.li.liu@oracle.com> Sender: linux-btrfs-owner@vger.kernel.org List-ID: map_private_extent_buffer() can return -EINVAL in two different cases, 1. when the requested contents span two pages if nodesize is larger than pagesize, 2. when it detects something insane. The 2nd one used to be only a WARN_ON(1), and we decided to return a error to callers, but we didn't fix up all its callers, which will be addressed by this patch. Without this, btrfs may end up with 'general protection', ie. reading invalid memory. Reported-by: Vegard Nossum Signed-off-by: Liu Bo --- fs/btrfs/ctree.c | 6 +++++- fs/btrfs/extent_io.c | 7 ++++++- 2 files changed, 11 insertions(+), 2 deletions(-) diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index 4602568..c49a500 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -1785,10 +1785,12 @@ static noinline int generic_bin_search(struct extent_buffer *eb, if (!err) { tmp = (struct btrfs_disk_key *)(kaddr + offset - map_start); - } else { + } else if (err == 1) { read_extent_buffer(eb, &unaligned, offset, sizeof(unaligned)); tmp = &unaligned; + } else { + return err; } } else { @@ -2825,6 +2827,8 @@ cow_done: } ret = key_search(b, key, level, &prev_cmp, &slot); + if (ret < 0) + goto done; if (level != 0) { int dec = 0; diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index a3412d6..aa44d3e 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -5333,6 +5333,11 @@ int read_extent_buffer_to_user(struct extent_buffer *eb, void __user *dstv, return ret; } +/* + * return 0 if the item is found within a page. + * return 1 if the item spans two page. + * return -EINVAL otherwise. + */ int map_private_extent_buffer(struct extent_buffer *eb, unsigned long start, unsigned long min_len, char **map, unsigned long *map_start, @@ -5347,7 +5352,7 @@ int map_private_extent_buffer(struct extent_buffer *eb, unsigned long start, PAGE_SHIFT; if (i != end_i) - return -EINVAL; + return 1; if (i == 0) { offset = start_offset; -- 2.5.5