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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 <[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]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: He Kuang <[email protected]>
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
This commit is contained in:
Wang Nan 2016-05-23 07:13:39 +00:00 • committed by Arnaldo Carvalho de Melo
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 <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];