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Groups > linux.kernel > #1400564

[PATCH 05/17] perf record: Prevent reading invalid data in record__mmap_read

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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(+)

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 21ef8a0..81c700d 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];
-- 
1.8.3.4

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[PATCH 00/17] perf tools: Support overwritable ring buffer Wang Nan <wangnan0@huawei.com> - 2016-05-13 10:00 +0200
  [PATCH 15/17] perf record: Read from backward ring buffer Wang Nan <wangnan0@huawei.com> - 2016-05-13 10:00 +0200
  [PATCH 01/17] perf tools: Extract __perf_evlist__mmap_read() Wang Nan <wangnan0@huawei.com> - 2016-05-13 10:00 +0200
    Re: [PATCH 01/17] perf tools: Extract __perf_evlist__mmap_read() Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-05-13 15:10 +0200
  [PATCH 09/17] perf tools: Detect avalibility of write_backward Wang Nan <wangnan0@huawei.com> - 2016-05-13 10:00 +0200
    Re: [PATCH 09/17] perf tools: Detect avalibility of write_backward Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-05-13 15:10 +0200
      Re: [PATCH 09/17] perf tools: Detect avalibility of write_backward "Wangnan (F)" <wangnan0@huawei.com> - 2016-05-20 17:40 +0200
        Re: [PATCH 09/17] perf tools: Detect avalibility of write_backward Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-05-20 17:40 +0200
  [PATCH 05/17] perf record: Prevent reading invalid data in record__mmap_read Wang Nan <wangnan0@huawei.com> - 2016-05-13 10:00 +0200
  [PATCH 17/17] perf tools: Don't warn about out of order event if write_backward is used Wang Nan <wangnan0@huawei.com> - 2016-05-13 10:00 +0200
  [PATCH 11/17] perf tools: Set write_backward attribut bit for overwrite events Wang Nan <wangnan0@huawei.com> - 2016-05-13 10:00 +0200
  [PATCH 04/17] perf tools: Operate multiple channels Wang Nan <wangnan0@huawei.com> - 2016-05-13 10:00 +0200
  [PATCH 08/17] perf record: Don't poll on overwrite channel Wang Nan <wangnan0@huawei.com> - 2016-05-13 10:00 +0200
    Re: [PATCH 08/17] perf record: Don't poll on overwrite channel Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-05-13 15:20 +0200
      Re: [PATCH 08/17] perf record: Don't poll on overwrite channel "Wangnan (F)" <wangnan0@huawei.com> - 2016-05-16 05:20 +0200
  [PATCH 16/17] perf record: Toggle overwrite ring buffer for reading Wang Nan <wangnan0@huawei.com> - 2016-05-13 10:00 +0200
  [PATCH 10/17] perf tools: Enable overwrite settings Wang Nan <wangnan0@huawei.com> - 2016-05-13 10:00 +0200
    Re: [PATCH 10/17] perf tools: Enable overwrite settings Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-05-16 15:40 +0200
  [PATCH 07/17] perf record: Don't read from and poll overwrite channel Wang Nan <wangnan0@huawei.com> - 2016-05-13 10:00 +0200
  [PATCH 12/17] perf tools: Record fd into perf_mmap Wang Nan <wangnan0@huawei.com> - 2016-05-13 10:00 +0200
  [PATCH 13/17] perf tools: Add API to pause a channel Wang Nan <wangnan0@huawei.com> - 2016-05-13 10:00 +0200
  [PATCH 14/17] perf record: Rename variable to make code clear Wang Nan <wangnan0@huawei.com> - 2016-05-13 10:10 +0200
  [PATCH 02/17] perf tools: Add evlist channel helpers Wang Nan <wangnan0@huawei.com> - 2016-05-13 10:10 +0200
    Re: [PATCH 02/17] perf tools: Add evlist channel helpers Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-05-13 15:10 +0200
      Re: [PATCH 02/17] perf tools: Add evlist channel helpers "Wangnan (F)" <wangnan0@huawei.com> - 2016-05-18 05:40 +0200
        Re: [PATCH 02/17] perf tools: Add evlist channel helpers Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com> - 2016-05-18 15:30 +0200
  [PATCH 03/17] perf tools: Automatically add new channel according to evlist Wang Nan <wangnan0@huawei.com> - 2016-05-13 10:20 +0200
  [PATCH 06/17] perf tools: Squash overwrite setting into channel Wang Nan <wangnan0@huawei.com> - 2016-05-13 10:20 +0200

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