Commit-ID: 21d7eb9a24739cdc5ea19c90a79e5a585866ba35 Gitweb: https://git.kernel.org/tip/21d7eb9a24739cdc5ea19c90a79e5a585866ba35 Author: Arnaldo Carvalho de Melo <a...@redhat.com> AuthorDate: Mon, 3 Sep 2018 15:02:22 -0300 Committer: Arnaldo Carvalho de Melo <a...@redhat.com> CommitDate: Mon, 3 Sep 2018 15:13:33 -0300
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.hun...@intel.com> Cc: Daniel Borkmann <dan...@iogearbox.net> Cc: David Ahern <dsah...@gmail.com> Cc: Jiri Olsa <jo...@kernel.org> Cc: Namhyung Kim <namhy...@kernel.org> Cc: Wang Nan <wangn...@huawei.com> Cc: Yonghong Song <y...@fb.com> Link: https://lkml.kernel.org/n/tip-jtsapwibyxrnv1xjfsgzp...@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo <a...@redhat.com> --- tools/perf/examples/bpf/augmented_syscalls.c | 13 +++++++------ 1 file 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) \
