[PATCH 18/21] xfs: fix null pointer dereference in tracepoint

[Andrey Albershteyn <aalbersh@kernel.org>]

Source kernel commit: 9202ee546b0cd71004eed7598546efe4660097da

If dfp is not NULL we exit early here, when dfp is NULL it's allocated
in xfs_defer_alloc() but not assigned. The tracepoint tries to
dereference members of dfp struct.

Signed-off-by: Andrey Albershteyn <aalbersh@kernel.org>
Fixes: 3f3cec031099c3 ("xfs: force small EFIs for reaping btree extents")
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
---
 libxfs/xfs_defer.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libxfs/xfs_defer.c b/libxfs/xfs_defer.c
index 3e36865fd127..eae2397fbff8 100644
--- a/libxfs/xfs_defer.c
+++ b/libxfs/xfs_defer.c
@@ -871,7 +871,7 @@ xfs_defer_add_barrier(
 	if (dfp)
 		return;
 
-	xfs_defer_alloc(&tp->t_dfops, &xfs_barrier_defer_type);
+	dfp = xfs_defer_alloc(&tp->t_dfops, &xfs_barrier_defer_type);
 
 	trace_xfs_defer_add_item(tp->t_mountp, dfp, NULL);
 }
-- 
2.55.0