ext4: Check return value of sb_getblk() and friends

Fail block allocation if sb_getblk() returns NULL. In that case,
sb_find_get_block() also likely to fail so that it should skip
calling ext4_forget().

Signed-off-by: Namhyung Kim <namhyung@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

2 files changed, 7 insertions, 0 deletions

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 58604fe11f4f..077c3c9c432e 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -761,6 +761,11 @@ static int ext4_alloc_branch(handle_t *handle, struct inode *inode,
                  * parent to disk.
                  */
                 bh = sb_getblk(inode->i_sb, new_blocks[n-1]);
+                if (unlikely(!bh)) {
+                        err = -EIO;
+                        goto failed;
+                }
+
                 branch[n].bh = bh;
                 lock_buffer(bh);
                 BUFFER_TRACE(bh, "call get_create_access");
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index d732ef5a835d..611c866ef3fe 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -4537,6 +4537,8 @@ void ext4_free_blocks(handle_t *handle, struct inode *inode,
                         if (!bh)
                                 tbh = sb_find_get_block(inode->i_sb,
                                                         block + i);
+                        if (unlikely(!tbh))
+                                continue;
                         ext4_forget(handle, flags & EXT4_FREE_BLOCKS_METADATA,
                                     inode, tbh, block + i);
                 }