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libperf evsel: Make use of FD robust.
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FD uses xyarray__entry that may return NULL if an index is out of
bounds. If NULL is returned then a segv happens as FD unconditionally
dereferences the pointer. This was happening in a case of with perf
iostat as shown below. The fix is to make FD an "int*" rather than an
int and handle the NULL case as either invalid input or a closed fd.

  $ sudo gdb --args perf stat --iostat  list
  ...
  Breakpoint 1, perf_evsel__alloc_fd (evsel=0x5555560951a0, ncpus=1, nthreads=1) at evsel.c:50
  50      {
  (gdb) bt
   #0  perf_evsel__alloc_fd (evsel=0x5555560951a0, ncpus=1, nthreads=1) at evsel.c:50
   #1  0x000055555585c188 in evsel__open_cpu (evsel=0x5555560951a0, cpus=0x555556093410,
      threads=0x555556086fb0, start_cpu=0, end_cpu=1) at util/evsel.c:1792
   #2  0x000055555585cfb2 in evsel__open (evsel=0x5555560951a0, cpus=0x0, threads=0x555556086fb0)
      at util/evsel.c:2045
   #3  0x000055555585d0db in evsel__open_per_thread (evsel=0x5555560951a0, threads=0x555556086fb0)
      at util/evsel.c:2065
   #4  0x00005555558ece64 in create_perf_stat_counter (evsel=0x5555560951a0,
      config=0x555555c34700 <stat_config>, target=0x555555c2f1c0 <target>, cpu=0) at util/stat.c:590
   #5  0x000055555578e927 in __run_perf_stat (argc=1, argv=0x7fffffffe4a0, run_idx=0)
      at builtin-stat.c:833
   #6  0x000055555578f3c6 in run_perf_stat (argc=1, argv=0x7fffffffe4a0, run_idx=0)
      at builtin-stat.c:1048
   #7  0x0000555555792ee5 in cmd_stat (argc=1, argv=0x7fffffffe4a0) at builtin-stat.c:2534
   #8  0x0000555555835ed3 in run_builtin (p=0x555555c3f540 <commands+288>, argc=3,
      argv=0x7fffffffe4a0) at perf.c:313
   #9  0x0000555555836154 in handle_internal_command (argc=3, argv=0x7fffffffe4a0) at perf.c:365
   #10 0x000055555583629f in run_argv (argcp=0x7fffffffe2ec, argv=0x7fffffffe2e0) at perf.c:409
   #11 0x0000555555836692 in main (argc=3, argv=0x7fffffffe4a0) at perf.c:539
  ...
  (gdb) c
  Continuing.
  Error:
  The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event (uncore_iio_0/event=0x83,umask=0x04,ch_mask=0xF,fc_mask=0x07/).
  /bin/dmesg | grep -i perf may provide additional information.

  Program received signal SIGSEGV, Segmentation fault.
  0x00005555559b03ea in perf_evsel__close_fd_cpu (evsel=0x5555560951a0, cpu=1) at evsel.c:166
  166                     if (FD(evsel, cpu, thread) >= 0)

v3. fixes a bug in perf_evsel__run_ioctl where the sense of a branch was
    backward.

Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lore.kernel.org/lkml/20210918054440.2350466-1-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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@captain5050 @acmel
captain5050 authored and acmel committed Sep 18, 2021
1 parent 57f0ff0 commit aba5dae
Showing 1 changed file with 41 additions and 23 deletions.
64 changes: 41 additions & 23 deletions tools/lib/perf/evsel.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -43,7 +43,7 @@ void perf_evsel__delete(struct perf_evsel *evsel)
free(evsel);
}

#define FD(e, x, y) (*(int *) xyarray__entry(e->fd, x, y))
#define FD(e, x, y) ((int *) xyarray__entry(e->fd, x, y))
#define MMAP(e, x, y) (e->mmap ? ((struct perf_mmap *) xyarray__entry(e->mmap, x, y)) : NULL)

int perf_evsel__alloc_fd(struct perf_evsel *evsel, int ncpus, int nthreads)
Expand All @@ -54,7 +54,10 @@ int perf_evsel__alloc_fd(struct perf_evsel *evsel, int ncpus, int nthreads)
int cpu, thread;
for (cpu = 0; cpu < ncpus; cpu++) {
for (thread = 0; thread < nthreads; thread++) {
FD(evsel, cpu, thread) = -1;
int *fd = FD(evsel, cpu, thread);

if (fd)
*fd = -1;
}
}
}
Expand All @@ -80,7 +83,7 @@ sys_perf_event_open(struct perf_event_attr *attr,
static int get_group_fd(struct perf_evsel *evsel, int cpu, int thread, int *group_fd)
{
struct perf_evsel *leader = evsel->leader;
int fd;
int *fd;

if (evsel == leader) {
*group_fd = -1;
Expand All @@ -95,10 +98,10 @@ static int get_group_fd(struct perf_evsel *evsel, int cpu, int thread, int *grou
return -ENOTCONN;

fd = FD(leader, cpu, thread);
if (fd == -1)
if (fd == NULL || *fd == -1)
return -EBADF;

*group_fd = fd;
*group_fd = *fd;

return 0;
}
Expand Down Expand Up @@ -138,7 +141,11 @@ int perf_evsel__open(struct perf_evsel *evsel, struct perf_cpu_map *cpus,

for (cpu = 0; cpu < cpus->nr; cpu++) {
for (thread = 0; thread < threads->nr; thread++) {
int fd, group_fd;
int fd, group_fd, *evsel_fd;

evsel_fd = FD(evsel, cpu, thread);
if (evsel_fd == NULL)
return -EINVAL;

err = get_group_fd(evsel, cpu, thread, &group_fd);
if (err < 0)
Expand All @@ -151,7 +158,7 @@ int perf_evsel__open(struct perf_evsel *evsel, struct perf_cpu_map *cpus,
if (fd < 0)
return -errno;

FD(evsel, cpu, thread) = fd;
*evsel_fd = fd;
}
}

Expand All @@ -163,9 +170,12 @@ static void perf_evsel__close_fd_cpu(struct perf_evsel *evsel, int cpu)
int thread;

for (thread = 0; thread < xyarray__max_y(evsel->fd); ++thread) {
if (FD(evsel, cpu, thread) >= 0)
close(FD(evsel, cpu, thread));
FD(evsel, cpu, thread) = -1;
int *fd = FD(evsel, cpu, thread);

if (fd && *fd >= 0) {
close(*fd);
*fd = -1;
}
}
}

Expand Down Expand Up @@ -209,13 +219,12 @@ void perf_evsel__munmap(struct perf_evsel *evsel)

for (cpu = 0; cpu < xyarray__max_x(evsel->fd); cpu++) {
for (thread = 0; thread < xyarray__max_y(evsel->fd); thread++) {
int fd = FD(evsel, cpu, thread);
struct perf_mmap *map = MMAP(evsel, cpu, thread);
int *fd = FD(evsel, cpu, thread);

if (fd < 0)
if (fd == NULL || *fd < 0)
continue;

perf_mmap__munmap(map);
perf_mmap__munmap(MMAP(evsel, cpu, thread));
}
}

Expand All @@ -239,15 +248,16 @@ int perf_evsel__mmap(struct perf_evsel *evsel, int pages)

for (cpu = 0; cpu < xyarray__max_x(evsel->fd); cpu++) {
for (thread = 0; thread < xyarray__max_y(evsel->fd); thread++) {
int fd = FD(evsel, cpu, thread);
struct perf_mmap *map = MMAP(evsel, cpu, thread);
int *fd = FD(evsel, cpu, thread);
struct perf_mmap *map;

if (fd < 0)
if (fd == NULL || *fd < 0)
continue;

map = MMAP(evsel, cpu, thread);
perf_mmap__init(map, NULL, false, NULL);

ret = perf_mmap__mmap(map, &mp, fd, cpu);
ret = perf_mmap__mmap(map, &mp, *fd, cpu);
if (ret) {
perf_evsel__munmap(evsel);
return ret;
Expand All @@ -260,7 +270,9 @@ int perf_evsel__mmap(struct perf_evsel *evsel, int pages)

void *perf_evsel__mmap_base(struct perf_evsel *evsel, int cpu, int thread)
{
if (FD(evsel, cpu, thread) < 0 || MMAP(evsel, cpu, thread) == NULL)
int *fd = FD(evsel, cpu, thread);

if (fd == NULL || *fd < 0 || MMAP(evsel, cpu, thread) == NULL)
return NULL;

return MMAP(evsel, cpu, thread)->base;
Expand Down Expand Up @@ -295,17 +307,18 @@ int perf_evsel__read(struct perf_evsel *evsel, int cpu, int thread,
struct perf_counts_values *count)
{
size_t size = perf_evsel__read_size(evsel);
int *fd = FD(evsel, cpu, thread);

memset(count, 0, sizeof(*count));

if (FD(evsel, cpu, thread) < 0)
if (fd == NULL || *fd < 0)
return -EINVAL;

if (MMAP(evsel, cpu, thread) &&
!perf_mmap__read_self(MMAP(evsel, cpu, thread), count))
return 0;

if (readn(FD(evsel, cpu, thread), count->values, size) <= 0)
if (readn(*fd, count->values, size) <= 0)
return -errno;

return 0;
Expand All @@ -318,8 +331,13 @@ static int perf_evsel__run_ioctl(struct perf_evsel *evsel,
int thread;

for (thread = 0; thread < xyarray__max_y(evsel->fd); thread++) {
int fd = FD(evsel, cpu, thread),
err = ioctl(fd, ioc, arg);
int err;
int *fd = FD(evsel, cpu, thread);

if (fd == NULL || *fd < 0)
return -1;

err = ioctl(*fd, ioc, arg);

if (err)
return err;
Expand Down

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