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tools lib traceevent: Zero should not be considered "not found" in eval_flag()

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Guilherme Cox found that:

 There is, however, a potential bug if there is an item with code zero
 that is not the first one in the symbol list, since eval_flag(..)
 returns 0 when it doesn't find anything.

That is, if you have the following enums:

enum {
  FOO_START = 0,
  FOO_GO    = 1,
  FOO_END   = 2
}

and then have:

  __print_symbolic(foo, FOO_GO, "go", FOO_START, "start",
		        FOO_END, "end")

If none of the enums are known to pevent, then eval_flag() will return
zero, and it will match it to the first item in the list, which would be
FOO_GO, which is not zero.

Luckily, in most cases, the first element would be zero, and the parsing
would match out of sheer luck.

Reported-by: Guilherme Cox <cox@computer.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/20150324145813.0bfe95ba@gandalf.local.home
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Steven Rostedt 2015-03-24 14:58:13 -04:00 • committed by Arnaldo Carvalho de Melo
commit 7c27f78a29
1 changed files with 5 additions and 5 deletions
Download patch file Download diff file Expand all files Collapse all files

10
tools/lib/traceevent/event-parse.c
View file

@ -3615,7 +3615,7 @@ static const struct flag flags[] = {
{ "HRTIMER_RESTART", 1 },
};
static unsigned long long eval_flag(const char *flag)
static long long eval_flag(const char *flag)
{
int i;
@ -3631,7 +3631,7 @@ static unsigned long long eval_flag(const char *flag)
if (strcmp(flags[i].name, flag) == 0)
return flags[i].value;
return 0;
return -1LL;
}
static void print_str_to_seq(struct trace_seq *s, const char *format,
@ -3705,7 +3705,7 @@ static void print_str_arg(struct trace_seq *s, void *data, int size,
struct print_flag_sym *flag;
struct format_field *field;
struct printk_map *printk;
unsigned long long val, fval;
long long val, fval;
unsigned long addr;
char *str;
unsigned char *hex;
@ -3764,11 +3764,11 @@ static void print_str_arg(struct trace_seq *s, void *data, int size,
print = 0;
for (flag = arg->flags.flags; flag; flag = flag->next) {
fval = eval_flag(flag->value);
if (!val && !fval) {
if (!val && fval < 0) {
print_str_to_seq(s, format, len_arg, flag->str);
break;
}
if (fval && (val & fval) == fval) {
if (fval > 0 && (val & fval) == fval) {
if (print && arg->flags.delim)
trace_seq_puts(s, arg->flags.delim);
print_str_to_seq(s, format, len_arg, flag->str);