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xfs: don't crash if reading a directory results in an unexpected hole 

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>
This commit is contained in:
Darrick J. Wong 2016-12-05 12:37:47 +11:00 committed by Dave Chinner
parent 356a322522
commit 96a3aefb8f
1 changed files with 1 additions and 1 deletions
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2
fs/xfs/libxfs/xfs_dir2_data.c
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@ -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;
}