[PATCH 1/2] dyndbg: dont panic over bad input

[Jim Cromie]

This BUG_ON, from 2009, caught the impossible case of a word-char both
starting and ending a string (loosely speaking).  A bad (reverted)
patch finally hit this case, but even "impossibly bad input" is no
reason to panic the kernel.  Instead pr_err and return -EINVAL.

Reported-by: Petr Mladek <pmladek@xxxxxxxx>
Signed-off-by: Jim Cromie <jim.cromie@xxxxxxxxx>
---
 lib/dynamic_debug.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 2d4dfd44b0fa5..90ddf07ce34fe 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -259,7 +259,10 @@ static int ddebug_tokenize(char *buf, char *words[], int maxwords)
 		} else {
 			for (end = buf; *end && !isspace(*end); end++)
 				;
-			BUG_ON(end == buf);
+			if (end == buf) {
+				pr_err("expected non-empty bareword");
+				return -EINVAL;
+			}
 		}
 
 		/* `buf' is start of word, `end' is one past its end */
-- 
2.26.2