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[v3,02/11] perf record: Prevent reading invalid data in record__mmap_read

Message ID 1463987628-163563-3-git-send-email-wangnan0@huawei.com
State Accepted
Commit 2d11c65071d489e20b3a811167507939dd8c2eac
Headers show

Commit Message

Wang Nan May 23, 2016, 7:13 a.m. UTC 
When record__mmap_read() requires data more than the size of ring
buffer, drop those data to avoid accessing invalid memory.

This can happen when reading from overwritable ring buffer, which
should be avoided. However, check this for robustness.

Signed-off-by: Wang Nan <wangnan0@huawei.com>

Signed-off-by: He Kuang <hekuang@huawei.com>

Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
---
 tools/perf/builtin-record.c | 8 ++++++++
 1 file changed, 8 insertions(+)

-- 
1.8.3.4
diff mbox

Patch

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index f3679c4..f302cc9 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -40,6 +40,7 @@ 
 #include <unistd.h>
 #include <sched.h>
 #include <sys/mman.h>
+#include <asm/bug.h>
 
 
 struct record {
@@ -98,6 +99,13 @@  static int record__mmap_read(struct record *rec, int idx)
 	rec->samples++;
 
 	size = head - old;
+	if (size > (unsigned long)(md->mask) + 1) {
+		WARN_ONCE(1, "failed to keep up with mmap data. (warn only once)\n");
+
+		md->prev = head;
+		perf_evlist__mmap_consume(rec->evlist, idx);
+		return 0;
+	}
 
 	if ((old & md->mask) + size != (head & md->mask)) {
 		buf = &data[old & md->mask];