Messages in this thread Patch in this message | | | From | Wang Nan <> | Subject | [PATCH v2 04/13] perf record: Prevent reading invalid data in record__mmap_read | Date | Fri, 20 May 2016 16:38:26 +0000 |
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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 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]; -- 1.8.3.4
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