Messages in this thread Patch in this message | | | Date | Thu, 19 Aug 2021 15:56:34 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH] libperf evsel: Make use of FD robust. |
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Em Wed, Aug 18, 2021 at 10:47:07PM -0700, Ian Rogers escreveu: > 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)
Humm
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; } }
void perf_evsel__close_fd(struct perf_evsel *evsel) { int cpu;
for (cpu = 0; cpu < xyarray__max_x(evsel->fd); cpu++) perf_evsel__close_fd_cpu(evsel, cpu); }
Isn't bounds checking being performed by the callers?
- Arnaldo
> Signed-off-by: Ian Rogers <irogers@google.com> > --- > 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..ede7af4d183c 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 || *fd < 0) > + return -1; > + > + err = ioctl(*fd, ioc, arg); > > if (err) > return err; > -- > 2.33.0.rc1.237.g0d66db33f3-goog
--
- Arnaldo
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