[PATCH v3] libperf evsel: Make use of FD robust.
From: Ian Rogers
Date: Sat Sep 18 2021 - 01:44:57 EST
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.
v2. is a rebase.
Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>
---
tools/lib/perf/evsel.c | 64 +++++++++++++++++++++++++++---------------
1 file changed, 41 insertions(+), 23 deletions(-)
diff --git a/tools/lib/perf/evsel.c b/tools/lib/perf/evsel.c
index d8886720e83d..8441e3e1aaac 100644
--- 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;
--
2.33.0.464.g1972c5931b-goog