[PATCH] xfs: fix NULL ptr in xfs_attr_leaf_get

[Mark Tinguely <mark.tinguely@oracle.com>]

The error path of xfs_attr_leaf_hasname() can leave a NULL
xfs_buf pointer. xfs_has_attr() checks for the NULL pointer but
the other callers do not.

We tripped over the NULL pointer in xfs_attr_leaf_get() but fix
the other callers too.

Fixes v5.8-rc4-95-g07120f1abdff ("xfs: Add xfs_has_attr and subroutines")
No reproducer.

Cc: stable@vger.kernel.org # v5.19+ with another port for v5.9 - v5.18
Signed-off-by: Mark Tinguely <mark.tinguely@oracle.com>
---
  fs/xfs/libxfs/xfs_attr.c | 6 ++++--
  1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
index 8c04acd30d48..25e2ecf20d14 100644
--- a/fs/xfs/libxfs/xfs_attr.c
+++ b/fs/xfs/libxfs/xfs_attr.c
@@ -1266,7 +1266,8 @@ xfs_attr_leaf_removename(
  
  	error = xfs_attr_leaf_hasname(args, &bp);
  	if (error == -ENOATTR) {
-		xfs_trans_brelse(args->trans, bp);
+		if (bp)
+			xfs_trans_brelse(args->trans, bp);
  		if (args->op_flags & XFS_DA_OP_RECOVERY)
  			return 0;
  		return error;
@@ -1305,7 +1306,8 @@ xfs_attr_leaf_get(xfs_da_args_t *args)
  	error = xfs_attr_leaf_hasname(args, &bp);
  
  	if (error == -ENOATTR)  {
-		xfs_trans_brelse(args->trans, bp);
+		if (bp)
+			xfs_trans_brelse(args->trans, bp);
  		return error;
  	} else if (error != -EEXIST)
  		return error;
-- 
2.50.1 (Apple Git-155)