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xfs: don't crash on unexpected holes in dir/attr btrees 

In quite a few places we call xfs_da_read_buf with a mappedbno that we
don't control, then assume that the function passes back either an error
code or a buffer pointer.  Unfortunately, if mappedbno == -2 and bno
maps to a hole, we get a return code of zero and a NULL buffer, which
means that we crash if we actually try to use that buffer pointer.  This
happens immediately when we set the buffer type for transaction context.

Therefore, check that we have no error code and a non-NULL bp before
trying to use bp.  This patch is a follow-up to an incomplete fix in
96a3aefb8f ("xfs: don't crash if reading a directory results in an
unexpected hole").

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
This commit is contained in:
Darrick J. Wong 2017-07-07 18:55:17 -07:00
parent 6eb0b8df9f
commit cd87d86792
4 changed files with 5 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
fs/xfs/libxfs/xfs_attr_leaf.c
View File

@ -351,7 +351,7 @@ xfs_attr3_leaf_read(
err = xfs_da_read_buf(tp, dp, bno, mappedbno, bpp,
XFS_ATTR_FORK, &xfs_attr3_leaf_buf_ops);
if (!err && tp)
if (!err && tp && *bpp)
xfs_trans_buf_set_type(tp, *bpp, XFS_BLFT_ATTR_LEAF_BUF);
return err;
}

2
fs/xfs/libxfs/xfs_da_btree.c
View File

@ -263,7 +263,7 @@ xfs_da3_node_read(
err = xfs_da_read_buf(tp, dp, bno, mappedbno, bpp,
which_fork, &xfs_da3_node_buf_ops);
if (!err && tp) {
if (!err && tp && *bpp) {
struct xfs_da_blkinfo *info = (*bpp)->b_addr;
int type;

2
fs/xfs/libxfs/xfs_dir2_block.c
View File

@ -139,7 +139,7 @@ xfs_dir3_block_read(
err = xfs_da_read_buf(tp, dp, mp->m_dir_geo->datablk, -1, bpp,
XFS_DATA_FORK, &xfs_dir3_block_buf_ops);
if (!err && tp)
if (!err && tp && *bpp)
xfs_trans_buf_set_type(tp, *bpp, XFS_BLFT_DIR_BLOCK_BUF);
return err;
}

4
fs/xfs/libxfs/xfs_dir2_leaf.c
View File

@ -268,7 +268,7 @@ xfs_dir3_leaf_read(
err = xfs_da_read_buf(tp, dp, fbno, mappedbno, bpp,
XFS_DATA_FORK, &xfs_dir3_leaf1_buf_ops);
if (!err && tp)
if (!err && tp && *bpp)
xfs_trans_buf_set_type(tp, *bpp, XFS_BLFT_DIR_LEAF1_BUF);
return err;
}
@ -285,7 +285,7 @@ xfs_dir3_leafn_read(
err = xfs_da_read_buf(tp, dp, fbno, mappedbno, bpp,
XFS_DATA_FORK, &xfs_dir3_leafn_buf_ops);
if (!err && tp)
if (!err && tp && *bpp)
xfs_trans_buf_set_type(tp, *bpp, XFS_BLFT_DIR_LEAFN_BUF);
return err;
}