[PATCH] s390/debug: Reject NULL debug info in debug_dump()

[Mikhail Zaslonko <zaslonko@linux.ibm.com>]

debug_dump() passes id on to debug_info_copy(), which dereferences
in->name unchecked. debug_unregister(), debug_set_size() and
debug_register_view() guard against a NULL id but debug_dump() does not.
Nothing reaches this today, but add the check for consistency.

Reported-by: Sashiko <sashiko-bot@kernel.org>
Closes: https://lore.kernel.org/all/20260910110147.96E851F000FF@smtp.kernel.org/
Signed-off-by: Mikhail Zaslonko <zaslonko@linux.ibm.com>
---
 arch/s390/kernel/debug.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/s390/kernel/debug.c b/arch/s390/kernel/debug.c
index b5bf8284dbfc..354ce78fc0cf 100644
--- a/arch/s390/kernel/debug.c
+++ b/arch/s390/kernel/debug.c
@@ -823,6 +823,9 @@ ssize_t debug_dump(debug_info_t *id, struct debug_view *view,
 	file_private_info_t *p_info;
 	size_t size, offset = 0;
 
+	if (!id)
+		return -EINVAL;
+
 	/* Need space for '\0' byte */
 	if (buf_size < 1)
 		return 0;
-- 
2.55.0