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[23/32] xfs: don't crash if reading a directory results in an unexpected hole

Message ID 1483976343-661-24-git-send-email-hch@lst.de (mailing list archive)
State Not Applicable, archived
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Commit Message

Christoph Hellwig Jan. 9, 2017, 3:38 p.m. UTC 
From: "Darrick J. Wong" <darrick.wong@oracle.com>

commit 96a3aefb8ffde23180130460b0b2407b328eb727 upstream.

In xfs_dir3_data_read, we can encounter the situation where err == 0 and
*bpp == NULL if the given bno offset happens to be a hole; this leads to
a crash if we try to set the buffer type after the _da_read_buf call.
Holes can happen due to corrupt or malicious entries in the bmbt data,
so be a little more careful when we're handling buffers.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
---
 fs/xfs/libxfs/xfs_dir2_data.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff mbox

Patch

diff --git a/fs/xfs/libxfs/xfs_dir2_data.c b/fs/xfs/libxfs/xfs_dir2_data.c
index 725fc78..e526f5a 100644
--- a/fs/xfs/libxfs/xfs_dir2_data.c
+++ b/fs/xfs/libxfs/xfs_dir2_data.c
@@ -329,7 +329,7 @@  xfs_dir3_data_read(
 
 	err = xfs_da_read_buf(tp, dp, bno, mapped_bno, bpp,
 				XFS_DATA_FORK, &xfs_dir3_data_buf_ops);
-	if (!err && tp)
+	if (!err && tp && *bpp)
 		xfs_trans_buf_set_type(tp, *bpp, XFS_BLFT_DIR_DATA_BUF);
 	return err;
 }