[tip: locking/kcsan] kcsan: Fix function matching in report

[tip-bot2 for Marco Elver]

The following commit has been merged into the locking/kcsan branch of tip:

Commit-ID:     f770ed10a9ee65529f3ec8d90eb374bbd8b7c238
Gitweb:        
https://git.kernel.org/tip/f770ed10a9ee65529f3ec8d90eb374bbd8b7c238
Author:        Marco Elver <el...@google.com>
AuthorDate:    Fri, 10 Apr 2020 18:44:17 +02:00
Committer:     Paul E. McKenney <paul...@kernel.org>
CommitterDate: Mon, 13 Apr 2020 17:18:15 -07:00

kcsan: Fix function matching in report

Pass string length as returned by scnprintf() to strnstr(), since
strnstr() searches exactly len bytes in haystack, even if it contains a
NUL-terminator before haystack+len.

Signed-off-by: Marco Elver <el...@google.com>
Signed-off-by: Paul E. McKenney <paul...@kernel.org>
---
 kernel/kcsan/report.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/kernel/kcsan/report.c b/kernel/kcsan/report.c
index ddc18f1..cf41d63 100644
--- a/kernel/kcsan/report.c
+++ b/kernel/kcsan/report.c
@@ -192,11 +192,11 @@ skip_report(enum kcsan_value_change value_change, 
unsigned long top_frame)
                 * maintainers.
                 */
                char buf[64];
+               int len = scnprintf(buf, sizeof(buf), "%ps", (void *)top_frame);
 
-               snprintf(buf, sizeof(buf), "%ps", (void *)top_frame);
-               if (!strnstr(buf, "rcu_", sizeof(buf)) &&
-                   !strnstr(buf, "_rcu", sizeof(buf)) &&
-                   !strnstr(buf, "_srcu", sizeof(buf)))
+               if (!strnstr(buf, "rcu_", len) &&
+                   !strnstr(buf, "_rcu", len) &&
+                   !strnstr(buf, "_srcu", len))
                        return true;
        }
 
@@ -262,15 +262,15 @@ static const char *get_thread_desc(int task_id)
 static int get_stack_skipnr(const unsigned long stack_entries[], int 
num_entries)
 {
        char buf[64];
+       int len;
        int skip = 0;
 
        for (; skip < num_entries; ++skip) {
-               snprintf(buf, sizeof(buf), "%ps", (void *)stack_entries[skip]);
-               if (!strnstr(buf, "csan_", sizeof(buf)) &&
-                   !strnstr(buf, "tsan_", sizeof(buf)) &&
-                   !strnstr(buf, "_once_size", sizeof(buf))) {
+               len = scnprintf(buf, sizeof(buf), "%ps", (void 
*)stack_entries[skip]);
+               if (!strnstr(buf, "csan_", len) &&
+                   !strnstr(buf, "tsan_", len) &&
+                   !strnstr(buf, "_once_size", len))
                        break;
-               }
        }
        return skip;
 }