dynamic_debug: fix ddebug_parse_query()

This fixes following scenario:

  $ echo 'file dynamic_debug.c line 1-123 +p' > /sys/kernel/debug/dynamic_debug/control
  -bash: echo: write error: Invalid argument
  $ dmesg | grep dynamic_debug
  dynamic_debug:ddebug_parse_query: last-line:123 < 1st-line:1
  dynamic_debug:ddebug_parse_query: query parse failed

Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com>
Cc: Jason Baron <jbaron@akamai.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 2 deletions

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index f959c39cc007..e488d9a03adc 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -352,8 +352,10 @@ static int ddebug_parse_query(char *words[], int nwords,
                                 return -EINVAL;
                         if (last) {
                                 /* range <first>-<last> */
-                                if (parse_lineno(last, &query->last_lineno)
-                                    < query->first_lineno) {
+                                if (parse_lineno(last, &query->last_lineno) < 0)
+                                        return -EINVAL;
+
+                                if (query->last_lineno < query->first_lineno) {
                                         pr_err("last-line:%d < 1st-line:%d\n",
                                                 query->last_lineno,
                                                 query->first_lineno);