From 415b35a55b57a701afe7391d32a6bb0193b7d3da Mon Sep 17 00:00:00 2001 From: Liu Bo Date: Fri, 17 Jun 2016 19:16:21 -0700 Subject: [PATCH] Btrfs: fix error handling in map_private_extent_buffer 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 Signed-off-by: David Sterba Signed-off-by: Chris Mason --- 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 6276add8538a..a85cf7d23309 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -1786,10 +1786,12 @@ 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 { @@ -2830,6 +2832,8 @@ 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 aaee3ef55ed8..75533adef998 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -5342,6 +5342,11 @@ 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 pages. + * 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, @@ -5356,7 +5361,7 @@ 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; -- 2.20.1