2018-03-27 1:16 GMT+02:00 Kees Cook <[email protected]>: > On Tue, Mar 13, 2018 at 12:51 PM, Salvatore Mesoraca > <[email protected]> wrote: >> Avoid a VLA[1] by using a real constant expression instead of a variable. >> The compiler should be able to optimize the original code and avoid using >> an actual VLA. Anyway this change is useful because it will avoid a false >> positive with -Wvla, it might also help the compiler generating better >> code. >> >> [1] https://lkml.org/lkml/2018/3/7/621 >> >> Signed-off-by: Salvatore Mesoraca <[email protected]> >> --- >> kernel/trace/ftrace.c | 7 +++---- >> 1 file changed, 3 insertions(+), 4 deletions(-) >> >> diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c >> index eac9ce2..adebb92 100644 >> --- a/kernel/trace/ftrace.c >> +++ b/kernel/trace/ftrace.c >> @@ -3902,14 +3902,13 @@ static bool module_exists(const char *module) >> { >> /* All modules have the symbol __this_module */ >> const char this_mod[] = "__this_module"; >> - const int modname_size = MAX_PARAM_PREFIX_LEN + sizeof(this_mod) + 1; >> - char modname[modname_size + 1]; >> + char modname[MAX_PARAM_PREFIX_LEN + sizeof(this_mod) + 1]; > > Actually, I think this needs to be "+ 2" (":" and NULL).
Ah, right! I'll fix it ASAP :) > >> unsigned long val; >> int n; >> >> - n = snprintf(modname, modname_size + 1, "%s:%s", module, this_mod); >> + n = snprintf(modname, sizeof(modname), "%s:%s", module, this_mod); >> >> - if (n > modname_size) >> + if (n > sizeof(modname) - 1) >> return false; >> >> val = module_kallsyms_lookup_name(modname); > > Otherwise, looks good! Thank you! Salvatore
