dynamic_debug: tighten up error checking on debug queries

Issue error when a match-spec is given multiple times in a rule.
Previous code kept last one, but was silent about it.  Docs imply only
one is allowed by saying match-specs are ANDed together, given that
module M cannot match both A and B.  Also error when last_line < 1st_line.

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Signed-off-by: Jason Baron <jbaron@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 33 insertions, 6 deletions

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index cde4dfe2b2d5..5a7bacc2e901 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -276,6 +276,19 @@ static char *unescape(char *str)
         return str;
 }
 
+static int check_set(const char **dest, char *src, char *name)
+{
+        int rc = 0;
+
+        if (*dest) {
+                rc = -EINVAL;
+                pr_err("match-spec:%s val:%s overridden by %s",
+                        name, *dest, src);
+        }
+        *dest = src;
+        return rc;
+}
+
 /*
  * Parse words[] as a ddebug query specification, which is a series
  * of (keyword, value) pairs chosen from these possibilities:
@@ -287,11 +300,15 @@ static char *unescape(char *str)
  * format <escaped-string-to-find-in-format>
  * line <lineno>
  * line <first-lineno>-<last-lineno> // where either may be empty
+ *
+ * Only 1 of each type is allowed.
+ * Returns 0 on success, <0 on error.
  */
 static int ddebug_parse_query(char *words[], int nwords,
                                struct ddebug_query *query)
 {
         unsigned int i;
+        int rc;
 
         /* check we have an even number of words */
         if (nwords % 2 != 0)
@@ -300,24 +317,32 @@ static int ddebug_parse_query(char *words[], int nwords,
 
         for (i = 0 ; i < nwords ; i += 2) {
                 if (!strcmp(words[i], "func"))
-                        query->function = words[i+1];
+                        rc = check_set(&query->function, words[i+1], "func");
                 else if (!strcmp(words[i], "file"))
-                        query->filename = words[i+1];
+                        rc = check_set(&query->filename, words[i+1], "file");
                 else if (!strcmp(words[i], "module"))
-                        query->module = words[i+1];
+                        rc = check_set(&query->module, words[i+1], "module");
                 else if (!strcmp(words[i], "format"))
-                        query->format = unescape(words[i+1]);
+                        rc = check_set(&query->format, unescape(words[i+1]),
+                                "format");
                 else if (!strcmp(words[i], "line")) {
                         char *first = words[i+1];
                         char *last = strchr(first, '-');
+                        if (query->first_lineno || query->last_lineno) {
+                                pr_err("match-spec:line given 2 times\n");
+                                return -EINVAL;
+                        }
                         if (last)
                                 *last++ = '\0';
                         if (parse_lineno(first, &query->first_lineno) < 0)
                                 return -EINVAL;
-                        if (last != NULL) {
+                        if (last) {
                                 /* range <first>-<last> */
-                                if (parse_lineno(last, &query->last_lineno) < 0)
+                                if (parse_lineno(last, &query->last_lineno)
+                                    < query->first_lineno) {
+                                        pr_err("last-line < 1st-line\n");
                                         return -EINVAL;
+                                }
                         } else {
                                 query->last_lineno = query->first_lineno;
                         }
@@ -325,6 +350,8 @@ static int ddebug_parse_query(char *words[], int nwords,
                         pr_err("unknown keyword \"%s\"\n", words[i]);
                         return -EINVAL;
                 }
+                if (rc)
+                        return rc;
         }
 
         if (verbose)