[PATCH 1/4] lib/dynamic_debug: add NULL check after kstrdup

[Martin Weiss]

kstrdup(saved_command_line, GFP_KERNEL) may return NULL under memory
pressure. Add a check to avoid NULL pointer dereference during boot-time
dynamic debug parameter parsing.

Signed-off-by: Martin Weiss <Martin.weiss2410@xxxxxxxxx>
---
 lib/dynamic_debug.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 18a71a9108d3..59a04057b509 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -1479,6 +1479,8 @@ static int __init dynamic_debug_init(void)
 	 * slightly noisy if verbose, but harmless.
 	 */
 	cmdline = kstrdup(saved_command_line, GFP_KERNEL);
+	if (!cmdline)
+		return 0; /* prevents a boot-time NULL deref */
 	parse_args("dyndbg params", cmdline, NULL,
 		   0, 0, 0, NULL, &ddebug_dyndbg_boot_param_cb);
 	kfree(cmdline);
-- 
2.54.0