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perf record: Prevent reading invalid data in record__mmap_read 

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>
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
Link: http://lkml.kernel.org/r/1463987628-163563-3-git-send-email-wangnan0@huawei.com
Signed-off-by: He Kuang <hekuang@huawei.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Wang Nan 2016-05-23 07:13:39 +00:00 committed by Arnaldo Carvalho de Melo
parent 65aea23387
commit 2d11c65071
1 changed files with 8 additions and 0 deletions
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8
tools/perf/builtin-record.c
View File

@ -40,6 +40,7 @@
#include <unistd.h> #include <unistd.h>
#include <sched.h> #include <sched.h>
#include <sys/mman.h> #include <sys/mman.h>
#include <asm/bug.h>
struct record { struct record {
@ -98,6 +99,13 @@ static int record__mmap_read(struct record *rec, int idx)
rec->samples++; rec->samples++;
size = head - old; 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)) { if ((old & md->mask) + size != (head & md->mask)) {
buf = &data[old & md->mask]; buf = &data[old & md->mask];