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libperf evsel: Make use of FD robust.
[ Upstream commit aba5dae ] 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> Signed-off-by: Sasha Levin <sashal@kernel.org>
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‎tools/lib/perf/evsel.c‎

Lines changed: 41 additions & 23 deletions
Original file line numberDiff line numberDiff line change
@@ -43,7 +43,7 @@ void perf_evsel__delete(struct perf_evsel *evsel)
4343
free(evsel);
4444
}
4545

46-
#define FD(e, x, y) (*(int *) xyarray__entry(e->fd, x, y))
46+
#define FD(e, x, y) ((int *) xyarray__entry(e->fd, x, y))
4747
#define MMAP(e, x, y) (e->mmap ? ((struct perf_mmap *) xyarray__entry(e->mmap, x, y)) : NULL)
4848

4949
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)
5454
int cpu, thread;
5555
for (cpu = 0; cpu < ncpus; cpu++) {
5656
for (thread = 0; thread < nthreads; thread++) {
57-
FD(evsel, cpu, thread) = -1;
57+
int *fd = FD(evsel, cpu, thread);
58+
59+
if (fd)
60+
*fd = -1;
5861
}
5962
}
6063
}
@@ -80,7 +83,7 @@ sys_perf_event_open(struct perf_event_attr *attr,
8083
static int get_group_fd(struct perf_evsel *evsel, int cpu, int thread, int *group_fd)
8184
{
8285
struct perf_evsel *leader = evsel->leader;
83-
int fd;
86+
int *fd;
8487

8588
if (evsel == leader) {
8689
*group_fd = -1;
@@ -95,10 +98,10 @@ static int get_group_fd(struct perf_evsel *evsel, int cpu, int thread, int *grou
9598
return -ENOTCONN;
9699

97100
fd = FD(leader, cpu, thread);
98-
if (fd == -1)
101+
if (fd == NULL || *fd == -1)
99102
return -EBADF;
100103

101-
*group_fd = fd;
104+
*group_fd = *fd;
102105

103106
return 0;
104107
}
@@ -138,7 +141,11 @@ int perf_evsel__open(struct perf_evsel *evsel, struct perf_cpu_map *cpus,
138141

139142
for (cpu = 0; cpu < cpus->nr; cpu++) {
140143
for (thread = 0; thread < threads->nr; thread++) {
141-
int fd, group_fd;
144+
int fd, group_fd, *evsel_fd;
145+
146+
evsel_fd = FD(evsel, cpu, thread);
147+
if (evsel_fd == NULL)
148+
return -EINVAL;
142149

143150
err = get_group_fd(evsel, cpu, thread, &group_fd);
144151
if (err < 0)
@@ -151,7 +158,7 @@ int perf_evsel__open(struct perf_evsel *evsel, struct perf_cpu_map *cpus,
151158
if (fd < 0)
152159
return -errno;
153160

154-
FD(evsel, cpu, thread) = fd;
161+
*evsel_fd = fd;
155162
}
156163
}
157164

@@ -163,9 +170,12 @@ static void perf_evsel__close_fd_cpu(struct perf_evsel *evsel, int cpu)
163170
int thread;
164171

165172
for (thread = 0; thread < xyarray__max_y(evsel->fd); ++thread) {
166-
if (FD(evsel, cpu, thread) >= 0)
167-
close(FD(evsel, cpu, thread));
168-
FD(evsel, cpu, thread) = -1;
173+
int *fd = FD(evsel, cpu, thread);
174+
175+
if (fd && *fd >= 0) {
176+
close(*fd);
177+
*fd = -1;
178+
}
169179
}
170180
}
171181

@@ -209,13 +219,12 @@ void perf_evsel__munmap(struct perf_evsel *evsel)
209219

210220
for (cpu = 0; cpu < xyarray__max_x(evsel->fd); cpu++) {
211221
for (thread = 0; thread < xyarray__max_y(evsel->fd); thread++) {
212-
int fd = FD(evsel, cpu, thread);
213-
struct perf_mmap *map = MMAP(evsel, cpu, thread);
222+
int *fd = FD(evsel, cpu, thread);
214223

215-
if (fd < 0)
224+
if (fd == NULL || *fd < 0)
216225
continue;
217226

218-
perf_mmap__munmap(map);
227+
perf_mmap__munmap(MMAP(evsel, cpu, thread));
219228
}
220229
}
221230

@@ -239,15 +248,16 @@ int perf_evsel__mmap(struct perf_evsel *evsel, int pages)
239248

240249
for (cpu = 0; cpu < xyarray__max_x(evsel->fd); cpu++) {
241250
for (thread = 0; thread < xyarray__max_y(evsel->fd); thread++) {
242-
int fd = FD(evsel, cpu, thread);
243-
struct perf_mmap *map = MMAP(evsel, cpu, thread);
251+
int *fd = FD(evsel, cpu, thread);
252+
struct perf_mmap *map;
244253

245-
if (fd < 0)
254+
if (fd == NULL || *fd < 0)
246255
continue;
247256

257+
map = MMAP(evsel, cpu, thread);
248258
perf_mmap__init(map, NULL, false, NULL);
249259

250-
ret = perf_mmap__mmap(map, &mp, fd, cpu);
260+
ret = perf_mmap__mmap(map, &mp, *fd, cpu);
251261
if (ret) {
252262
perf_evsel__munmap(evsel);
253263
return ret;
@@ -260,7 +270,9 @@ int perf_evsel__mmap(struct perf_evsel *evsel, int pages)
260270

261271
void *perf_evsel__mmap_base(struct perf_evsel *evsel, int cpu, int thread)
262272
{
263-
if (FD(evsel, cpu, thread) < 0 || MMAP(evsel, cpu, thread) == NULL)
273+
int *fd = FD(evsel, cpu, thread);
274+
275+
if (fd == NULL || *fd < 0 || MMAP(evsel, cpu, thread) == NULL)
264276
return NULL;
265277

266278
return MMAP(evsel, cpu, thread)->base;
@@ -295,17 +307,18 @@ int perf_evsel__read(struct perf_evsel *evsel, int cpu, int thread,
295307
struct perf_counts_values *count)
296308
{
297309
size_t size = perf_evsel__read_size(evsel);
310+
int *fd = FD(evsel, cpu, thread);
298311

299312
memset(count, 0, sizeof(*count));
300313

301-
if (FD(evsel, cpu, thread) < 0)
314+
if (fd == NULL || *fd < 0)
302315
return -EINVAL;
303316

304317
if (MMAP(evsel, cpu, thread) &&
305318
!perf_mmap__read_self(MMAP(evsel, cpu, thread), count))
306319
return 0;
307320

308-
if (readn(FD(evsel, cpu, thread), count->values, size) <= 0)
321+
if (readn(*fd, count->values, size) <= 0)
309322
return -errno;
310323

311324
return 0;
@@ -318,8 +331,13 @@ static int perf_evsel__run_ioctl(struct perf_evsel *evsel,
318331
int thread;
319332

320333
for (thread = 0; thread < xyarray__max_y(evsel->fd); thread++) {
321-
int fd = FD(evsel, cpu, thread),
322-
err = ioctl(fd, ioc, arg);
334+
int err;
335+
int *fd = FD(evsel, cpu, thread);
336+
337+
if (fd == NULL || *fd < 0)
338+
return -1;
339+
340+
err = ioctl(*fd, ioc, arg);
323341

324342
if (err)
325343
return err;

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