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| author | Arnaldo Carvalho de Melo <acme@redhat.com> | 2018-09-03 15:02:22 -0300 |
|---|---|---|
| committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2018-09-03 15:13:33 -0300 |
| commit | 21d7eb9a24739cdc5ea19c90a79e5a585866ba35 (patch) | |
| tree | 03bf9d78e5f922bb733ee6d93bb03b52dffb0f57 /tools/perf/examples | |
| parent | 58094c48f4079cfc784f53a73caaa446db436389 (diff) | |
| download | linux-21d7eb9a24739cdc5ea19c90a79e5a585866ba35.tar.bz2 | |
perf augmented_syscalls: Check probe_read_str() return separately
Using a value returned from probe_read_str() to tell how many bytes to
copy using perf_event_output() has issues in some older kernels, like
4.17.17-100.fc27.x86_64, so separate the bounds checking done on how
many bytes to copy to a separate variable, so that the next patch has
only what is being done to make the test pass on older BPF validators.
For reference, see the discussion in this thread:
https://www.spinics.net/lists/netdev/msg480099.html
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Cc: Yonghong Song <yhs@fb.com>
Link: https://lkml.kernel.org/n/tip-jtsapwibyxrnv1xjfsgzp0fj@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf/examples')
| -rw-r--r-- | tools/perf/examples/bpf/augmented_syscalls.c | 13 |
1 files changed, 7 insertions, 6 deletions
diff --git a/tools/perf/examples/bpf/augmented_syscalls.c b/tools/perf/examples/bpf/augmented_syscalls.c index 1419a9186937..0decbcfa8b90 100644 --- a/tools/perf/examples/bpf/augmented_syscalls.c +++ b/tools/perf/examples/bpf/augmented_syscalls.c @@ -33,9 +33,9 @@ struct syscall_exit_args { }; struct augmented_filename { - int size; - int reserved; - char value[256]; + unsigned int size; + int reserved; + char value[256]; }; #define augmented_filename_syscall(syscall) \ @@ -46,14 +46,15 @@ struct augmented_enter_##syscall##_args { \ int syscall_enter(syscall)(struct syscall_enter_##syscall##_args *args) \ { \ struct augmented_enter_##syscall##_args augmented_args = { .filename.reserved = 0, }; \ + unsigned int len = sizeof(augmented_args); \ probe_read(&augmented_args.args, sizeof(augmented_args.args), args); \ augmented_args.filename.size = probe_read_str(&augmented_args.filename.value, \ sizeof(augmented_args.filename.value), \ args->filename_ptr); \ + if (augmented_args.filename.size < sizeof(augmented_args.filename.value)) \ + len -= sizeof(augmented_args.filename.value) - augmented_args.filename.size; \ perf_event_output(args, &__augmented_syscalls__, BPF_F_CURRENT_CPU, \ - &augmented_args, \ - (sizeof(augmented_args) - sizeof(augmented_args.filename.value) + \ - augmented_args.filename.size)); \ + &augmented_args, len); \ return 0; \ } \ int syscall_exit(syscall)(struct syscall_exit_args *args) \ |