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 <vegard.nossum@oracle.com>
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>

1 files changed, 5 insertions, 1 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;