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
96a3aefb8ffde231 ("xfs: don't crash if reading a directory results in an
unexpected hole").

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

diff --git a/fs/xfs/libxfs/xfs_attr_leaf.c b/fs/xfs/libxfs/xfs_attr_leaf.c
index 2852521fc8ecf797be90372a23c3343e9a8039dc..c6c15e5717e42a2afd20710d12e021e87136985b 100644 (file)
--- a/fs/xfs/libxfs/xfs_attr_leaf.c
+++ b/fs/xfs/libxfs/xfs_attr_leaf.c
@@ -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;
 }

diff --git a/fs/xfs/libxfs/xfs_da_btree.c b/fs/xfs/libxfs/xfs_da_btree.c
index 356f21d5cd3579b935ab057313a3895d428a751d..6d4335815c3f80681da6fe7251887a0c9ee0432e 100644 (file)
--- a/fs/xfs/libxfs/xfs_da_btree.c
+++ b/fs/xfs/libxfs/xfs_da_btree.c
@@ -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;
 

diff --git a/fs/xfs/libxfs/xfs_dir2_block.c b/fs/xfs/libxfs/xfs_dir2_block.c
index aa17cb788946b02ebb54a7a75350ae43869a758a..43c902f7a68d4da0c6eb9853aeb14b5fbbe52340 100644 (file)
--- a/fs/xfs/libxfs/xfs_dir2_block.c
+++ b/fs/xfs/libxfs/xfs_dir2_block.c
@@ -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;
 }

diff --git a/fs/xfs/libxfs/xfs_dir2_leaf.c b/fs/xfs/libxfs/xfs_dir2_leaf.c
index 7002024a5d0d4a5031c76d65dd4354df24207800..27297a689d9c26acea0a10e643b8c0694867b8b4 100644 (file)
--- a/fs/xfs/libxfs/xfs_dir2_leaf.c
+++ b/fs/xfs/libxfs/xfs_dir2_leaf.c
@@ -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;
 }