[PATCH 4.9 05/30] udf: Fix crash on IO error during truncate

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jan Kara <jack@xxxxxxx>

commit d3ca4651d05c0ff7259d087d8c949bcf3e14fb46 upstream.

When truncate(2) hits IO error when reading indirect extent block the
code just bugs with:

kernel BUG at linux-4.15.0/fs/udf/truncate.c:249!
...

Fix the problem by bailing out cleanly in case of IO error.

CC: stable@xxxxxxxxxxxxxxx
Reported-by: jean-luc malet <jeanluc.malet@xxxxxxxxx>
Signed-off-by: Jan Kara <jack@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 fs/udf/truncate.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/fs/udf/truncate.c
+++ b/fs/udf/truncate.c
@@ -260,6 +260,9 @@ void udf_truncate_extents(struct inode *
 			epos.block = eloc;
 			epos.bh = udf_tread(sb,
 					udf_get_lb_pblock(sb, &eloc, 0));
+			/* Error reading indirect block? */
+			if (!epos.bh)
+				return;
 			if (elen)
 				indirect_ext_len =
 					(elen + sb->s_blocksize - 1) >>