libperf evsel: Make use of FD robust.

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>

diff --git a/tools/lib/perf/evsel.c b/tools/lib/perf/evsel.c
index d888672..8441e3e 100644 (file)
--- a/tools/lib/perf/evsel.c
+++ b/tools/lib/perf/evsel.c
@@ -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)
@@ -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;
                        }
                }
        }
@@ -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;
@@ -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;
 }
@@ -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)
@@ -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;
                }
        }
 
@@ -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;
+               }
        }
 }
 
@@ -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));
                }
        }
 
@@ -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;
@@ -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;
@@ -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;
@@ -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;