On Tue, Sep 14, 2021 at 2:39 PM Rafael David Tinoco <rafaeldtinoco@xxxxxxxxx> wrote: > > > > - char cmd[192], probename[128], probefunc[128]; > > + char cmd[288] = "\0", probename[128] = "\0", probefunc[128] = "\0"; > > const char *file = "/sys/kernel/debug/tracing/kprobe_events"; > > I had gcc-10 with: > > libbpf.c: In function ‘poke_kprobe_events’: > libbpf.c:9012:37: error: ‘%s’ directive output may be truncated writing up to 127 bytes into a region of size between 62 and 189 [-Werror=format-truncation=] > 9012 | snprintf(cmd, sizeof(cmd), "%c:%s %s", > | ^~ > In file included from /usr/include/stdio.h:866, > from libbpf.c:17: > /usr/include/x86_64-linux-gnu/bits/stdio2.h:71:10: note: ‘__builtin___snprintf_chk’ output between 4 and 258 bytes into a destination of size 192 > 71 | return __builtin___snprintf_chk (__s, __n, __USE_FORTIFY_LEVEL - 1, > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > 72 | __glibc_objsize (__s), __fmt, > | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > 73 | __va_arg_pack ()); > | ~~~~~~~~~~~~~~~~~ > cc1: all warnings being treated as errors > > locally AND it fixed the issue for me but Alexei reported: > > https://github.com/kernel-patches/bpf/runs/3603448190 > > with a truncation of max 258 bytes. I raised cmd size to 288. Right, if offset != 0 GCC is able to deduce that sizeof(probename) + sizeof(probefunc) add up to 256 (plus few more characters in format string) and that will be truncated in cmd. It completely ignores such possibility when offset == 0 and we use name as is. Either way, I bumped the cmd size to 256 and force-pushed. It should build fine now. Sorry for delay. > > Let's see if that fixes the issue. >
