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 <[email protected]> Signed-off-by: He Kuang <[email protected]> Cc: Arnaldo Carvalho de Melo <[email protected]> Cc: Jiri Olsa <[email protected]> Cc: Masami Hiramatsu <[email protected]> Cc: Namhyung Kim <[email protected]> Cc: Zefan Li <[email protected]> Cc: [email protected] --- 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 fa16099..9ffdef9 100644 --- a/tools/perf/builtin-record.c +++ b/tools/perf/builtin-record.c @@ -38,6 +38,7 @@ #include <unistd.h> #include <sched.h> #include <sys/mman.h> +#include <asm/bug.h> struct record { @@ -96,6 +97,13 @@ 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
